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Journal

November 11, 2023/in Uncategorized /by Daniel Jennings

Virtual Lab: Sex-Linked Traits

Worksheet

Please make sure you have read through all of the information in the “Questions” and “Information” areas. If you come upon terms that are unfamiliar to you, please refer to your textbook for further explanation or search the word here: http://encarta.msn.com/encnet/features/dictionary/dictionaryhome.aspx

Next, complete the Punnett square activity by clicking on the laboratory notebook. Please be sure to note the possible genotypes of the various flies:

Female, red eyes	Female, red eyes	Female, white eyes	Male, red eyes	Male, white eyes
XRXR	XrXR	XrXr	XRY	XrY

When you have completed the Punnett square activity, return to the laboratory scene to begin the actual laboratory activity.

In this exercise, you will perform a Drosophila mating in order to observe sex-linked trait transmission. Please click on the shelf in the laboratory. Here you will find vials of fruit flies. On the TOP shelf, please click on one of the female vials (on the left side) and then drag it to the empty vial on the shelf below. Please repeat this step using one of the male vials (on the right side). These flies will be used as the parental (P) generation. You may switch your parent choices at any time by dragging out old selections and dragging in new flies. Use the Punnett square below to predict the genotypes/phenotypes of the offspring (Note: refer to the genotype table you created above if needed):

Genotype: XRXR

Phenotype:Red eye, female

Genotype:XRXR

Phenotype: Red eye, female

Genotype:XRY

Phenotype: Red eye, male

Genotype:XRY

Phenotype: Red eye, male

__50_% Female, red eye _0__% Female, white eye _50__% Male, red eye _0__% Male, white eye

When you are finished, click “Mate and Sort”.

You will now see information appear in the vials sitting on the next shelf below. These are the offspring of the parent flies you selected above, and they represent the first filial (F1) generation. In your “Data Table” on the bottom of the page and/or on Table I found at the end of this Worksheet, please input the numbers of each sex and phenotype combination for the F1 generation. These numbers will be placed into the first row marked “P generation Cross”.

You will next need to select one of the F1 female flies and one of the F1 male flies to create the second filial (F2) generation. Drag your selections down to the empty vial on the next shelf below and fill in the Punnett square below to predict the offspring:

Genotype: XRXR

Phenotype:Red eye, female

Genotype:XRXR

Phenotype: Red eye, female

Genotype:XRY

Phenotype: Red eye, male

Genotype:XRY

Phenotype: Red eye, male

__50_% Female, red eye _0__% Female, white eye _50__% Male, red eye _0__% Male, white eye

After clicking “Mate and Sort”, you will now have information on their offspring (the F2 generation) to input into your “Data Table” or Worksheet below. This information will be placed into the second row marked “F1 generation Cross”.

NOTE: there are additional lines remaining to use if your instructor requires the analysis of additional crosses.

Please finish this exercise by opening the “Journal” link at the bottom of the page and answering the questions.

Table I:

Cross Type	Phenotype of Male Parent	Phenotype of Female Parent	Number of Red eye, Male Offspring	Number of White eye, Male Offspring	Number of Red eye, Female Offspring	Number of White eye, Female Offspring
P Generation Cross	Red	Red	50	0	50	0
F1 Generation Cross	Red	Red	50	0	50	0
P Generation Cross	White	Red	47	0	53	0
F1 Generation Cross	Red	Red	22	25	53	0
P Generation Cross	Red	White	0	49	51	0
F1 Generation Cross	White	Red	27	28	20	25
P Generation Cross	White	White	0	51	0	49
F1 Generation Cross	White	White	0	51	0	49

Post-laboratory Questions:

Through fruit fly studies, geneticists have discovered a segment of DNA called the homeobox which appears to control:

Sex development in the flies

Life span in the flies

Final body plan development in the flies

The genotype of a red-eyed male fruit fly would be:

XRXR

XRXr

XrXr

A or B

None of the above

Sex-linked traits:

Can be carried on the Y chromosome

Affect males and females equally

Can be carried on chromosome 20

A and B

None of the above -2

A monohybrid cross analyzes:

One trait, such as eye color

Two traits, such as eye color and wing shape

The offspring of one parent

A female with the genotype “XRXr”:

Is homozygous for the eye color gene

Is heterozygous for the eye color gene

Is considered a carrier for the eye color gene

A and B

B and C

In T.H. Morgan’s experiments:

He concluded that the gene for fruit fly eye color is carried on the X chromosome

He found that his F1 generation results always mirrored those predicted by Mendelian Laws of Inheritance

He found that his F2 generation results always mirrored those predicted by Mendelian Laws of Inheritance

A and B

All of the above

In this laboratory exercise:

The Punnett square will allow you to predict the traits of the offspring created in your crosses

XR will represent the recessive allele for eye color, which is white

Xr will represent the dominant allele for eye color, which is red

All of the above

In a cross between a homozygous red-eyed female fruit fly and a white-eyed male, what percentage of the female offspring is expected to be carriers?

25%

50%

75%

100%

In a cross between a white-eyed female and a red-eyed male:

All males will have red eyes

50% of males will have white eyes

All females will have red eyes

50% of females will have white eyes

In human diseases that are X-linked dominant, one dominant allele causes the disease. If an affected father has a child with an unaffected mother:

All males are unaffected

Some but not all males are affected

All females are unaffected

Some but not all females are affected

Journal Questions:

1. In a mating between a red-eyed male fruit fly and a red-eyed heterozygous female, what percentage of the female offspring is expected to be carriers? How did you determine the percentage?

2. In a mating between a red-eyed male fruit fly and a white-eyed female fruit fly, what percentage of the male offspring will have white eyes? Describe how you determined the percentage.

3. Hemophilia, a blood disorder in humans, results from a sex-linked recessive allele. Suppose that a daughter of a mother without the allele and a father with the allele marries a man with hemophilia. What is the probability that the daughter’s children will develop the disease? Describe how you determined the probability.

4. Colorblindness results from a sex-linked recessive allele. Determine the genotypes of the offspring that result from a cross between a color-blind male and a homozygous female who has normal vision. Describe how you determined the genotypes of the offspring.

5. Explain why sex-linked traits appear more often in males than in females.

6. In humans, hemophilia is a sex-linked recessive trait. It is located on the X chromosome. Remember that the human female genotype is XX and the male genotype is XY. Suppose that a daughter of a mother without the allele and a father with the allele marries a man with hemophilia. What is the probability that the daughter’s children will develop the disease? Describe how you determined the probability.

7. Colorblindness also results from a sex-linked recessive allele on the X chromosome in humans. Determine the genotypes of the offspring that result from a cross between a color-blind male and a homozygous female who has normal vision. Describe how you determined the genotypes of the offspring.

8. Based on the traits explained in questions 6 and 7, explain why sex-linked traits in humans appear more often in males than in females.

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Population Ecology

November 11, 2023/in Uncategorized /by Daniel Jennings

Population Ecology Hands-On Labs, Inc. Version 42-0281-00-02 Review the safety materials and wear goggles when working with chemicals. Read the entire exercise before you begin. Take time to organize the materials you will need and set aside a safe work space in which to complete the exercise. Experiment Summary: You will explore the field of population ecology and survey factors involved in the decline, expansion, and maintenance of a population. Simulated growth of a population will be modeled, graphed, and analyzed. You will use quantitative data from a cemetery population to study demographics. www.HOLscience.com 1 © Hands-On Labs, Inc. EXPERIMENT Learning Objectives Upon completion of this laboratory, you will be able to: ● Define species, population, and metapopulation. ● Differentiate between density-dependent and density-independent factors and describe how each can influence population size. ● Outline factors that influence carrying capacity and describe the potential consequences of overpopulation. ● Illustrate graphs of linear and exponential population growth. ● Describe how demography data may be used to calculate probability of mortality. ● Model population growth and determine if the growth was linear, exponential, or had no observable pattern. ● Determine constraints placed on a modeled population and draw conclusions about carrying capacity. ● Use birth and mortality data of a cemetery to investigate demography. ● Determine probability of death within a cohort. Time Allocation: 3.5 hours Note: This experiment suggests a field trip to a local cemetery for data collection. Please plan your time accordingly. www.HOLscience.com 2 ©Hands-On Labs, Inc. Experiment Population Ecology Materials Student Supplied Materials Quantity Item Description 3 Sheets of paper (optional) 1 Pen or pencil 1 Access to a cemetery (optional) 1 Access to a printer (optional) HOL Supplied Materials Quantity Item Description 1 Packs of dice, mini (100 pcs) 1 Cup, plastic, 9 oz., short 1 HOL Supplied Cemetery Data Supplemental Document Note: To fully and accurately complete all lab exercises, you will need access to: 1. A computer to upload digital camera images. 2. Basic photo editing software such as Microsoft Word® or PowerPoint®, to add labels, leader lines, or text to digital photos. 3. Subject-specific textbook or appropriate reference resources from lecture content or other suggested resources. Note: The packaging and/or materials in this LabPaq kit may differ slightly from that which is listed above. For an exact listing of materials, refer to the Contents List included in your LabPaq kit. www.HOLscience.com 3 ©Hands-On Labs, Inc. Experiment Population Ecology Background Species and Populations A species is a group of organisms that share many common characteristics and breed among themselves to produce fertile offspring. Individuals of a species that occupy a defined area at the same time are called a population. The habitat area of a population is often naturally enclosed within geographical boundaries, such as rivers or mountains. See Figure 1. In research studies about populations, scientists often define artificial boundaries. For example, scientists may investigate the population within a county or state boundary. Figure 1. Small population of water lilies (family Nymphaeaceae) inhabiting a pond. © yuriy kulik When suitable habitat is patchy or fragmented, populations can be spatially isolated, but members of the population can have some level of interaction with one another. When this occurs, the interacting populations are referred to as a metapopulation. An example of a species that is often found as a metapopulation is the desert bighorn sheep (Ovis canadensis). See Figure 2. The bighorn sheep occupies steep slopes of mountains that are separated by flat lowlands. Although the lowlands are an unsuitable long-term habitat for the sheep, individuals and groups of sheep are able to travel through the lowlands to adjacent mountains, resulting in interaction among individuals of different but connected populations. www.HOLscience.com 4 ©Hands-On Labs, Inc. Experiment Population Ecology Figure 2. Bighorn sheep. © Shane W. Thompson Population Density Biologists who study population ecology often investigate population size and factors involved in the decline, expansion, and maintenance of a population. Data about populations include the following: ● Mortality (death) and birth rates ● Movement of members into and out of the population (immigration and emigration) ● Number of individuals in a group, or cohort (for this experiment cohorts are the age classes of deceased individuals) ● Spatial distribution of species ● Population density (the number of individuals per unit area) Factors related to the density of a population, called density-dependent factors, affect population growth by reducing or increasing the population size. For example, the ability to acquire a mate is a density-dependent factor. When population density is great, competition for mates increases. Members of the population may spend more energy competing for mates than actually mating, and the population size can subsequently decrease due to reduced births. On the other hand, when population density is optimal, competition may be relatively low and mating opportunities may be high, resulting in growth of the population. Other density-dependent factors include resource availability, predation rates, and disease transmission. Density-independent factors influence population growth but are not dependent on population density. Consider how the population density of trees may be affected by weather patterns and wildfires. Growth rates can follow various patterns, as shown in Figure 3. When resources are unlimited, a population’s growth rate can be exponential. Although the graph of exponential growth illustrates a potentially great increase in population size, no population can grow indefinitely. In nature, members of the population will eventually consume available resources, and the population size will ultimately plateau or decline due to density-dependent factors. www.HOLscience.com 5 ©Hands-On Labs, Inc. Experiment Population Ecology Figure 3. Population growth patterns. A. Linear. B. Exponential. Every natural area has a carrying capacity, a decided number of individuals that can be supported given the area’s limited resources. Carrying capacity is influenced not only by the number of members of a single population, but also members of competing populations. Furthermore, a given population may act as a resource for another population; for example, voles are a food resource for owls. Carrying capacities are in constant flux, as they are affected by both densitydependent and density-independent factors. In the event that overpopulation occurs and the carrying capacity is exceeded, a population collapse can occur; whereby the population size decreases dramatically. When a population completely collapses and no members remain, the population is locally extinct, or extirpated. Human Populations A subset of population ecology, demography, is the study of human populations. Cemeteries are an excellent place to study demography as they provide data on both the birth and death dates of individuals of a local population. This information can be used in turn to determine the probability of death and survival at different ages in a population. Table 1 is an example analysis of mortality. To generate the table, the number of individuals that died in each cohort (based on age class) must be determined. For example, the first cohort listed in Table 1 includes individuals that died from age one to nine. From this information, probability of mortality can be calculated. According to Table 1 there is a 15% probability of death in this specific population, between ages one and nine. Closely study the table descriptions provided below. www.HOLscience.com 6 ©Hands-On Labs, Inc. Experiment Population Ecology Table 1. Cemetery Demography Data. Cohort (X) Number of deaths (D) Frequency of population in cohort (d) Frequency of survivorship entering the cohort (l) Probability of death within a cohort (Q) 1-9 24 0.15 1.00 0.15 10-19 20 0.13 0.85 0.15 20-29 5 0.03 0.73 0.04 30-39 10 0.06 0.69 0.09 40-49 16 0.10 0.63 0.16 50-59 40 0.25 0.53 0.47 60-69 35 0.22 0.28 0.78 70+ 10 0.06 0.06 1.00 Table Description: ● Cohort (X) – The age intervals of deceased individuals ● Number of deaths (D) – The number of individuals that died in each cohort ● Frequency of population in cohort (d) – The portion of the population that died in each cohort, d = D / Total Population Size ● Frequency of survivorship entering the cohort (l) – The portion of the population that enters the cohort, l cohort2 = lcohort1 – dcohort1 ● Probability of death within a cohort (Q) – The probability that any given individual will die within a cohort, Q = d / l www.HOLscience.com 7 ©Hands-On Labs, Inc. Experiment Population Ecology Exercise 1: Modeling Population Growth In this exercise, you will use dice to model population growth. Each die will represent an individual; new individuals will be born, and individuals will also die. You will track the entire population until the population density (number of individuals) reaches 100. 1. Before you begin to model population growth, examine the rules listed below and shown in Figure 4. Rules ● Each die represents 1 individual of the population. ● You will start with 4 individuals. ● You will roll the dice to investigate births and deaths of the population. ● The number of dots on each die will represent a birth, a death, or neither birth nor death. ● Birth = 1, 4 ● Death = 6 ● Neither = 2, 3, 5 Figure 4. Rules of population growth activity. 2. Select 4 dice and place them in the cup. These dice represent the 4 individuals comprising generation 1, the initial population. Note: The color of the dice does not matter. 3. In Data Table 1 of your Lab Report Assistant, record the “Initial population size (N)” (for the first generation, the initial population size is 4). www.HOLscience.com 8 ©Hands-On Labs, Inc. Experiment Population Ecology 4. Cover the cup with your hand and shake the dice. Gently pour the dice onto a table or work surface. Important Note: Pouring the dice out too quickly or too high from the work surface may result in lost dice. Take care not to inadvertently lose individuals. 5. Determine the number of individuals that were born (any dice displaying numbers 1 and 4). Determine the number of individuals that died (any dice displaying number 6). See Figure 5. Figure 5. Example first generation: 2 individuals gave birth, and 1 individual died. 6. Record the “Number of births (B)” and the “Number of deaths (D)” in Data Table 1. 7. Remove any dead individuals. For example, in Figure 5 above, the dead individual should be removed from the population and returned to the bag. 8. Add a die for each birth. For example, in Figure 5 above, 2 dice should be added to the population. 9. Calculate the final population size and record the value in Data Table 1. Use the following equation: Final population size = N + B – D 10. Count the number of dice in your population to ensure that it equals the value recorded for “final population size” and return the dice to the cup. 11. To obtain data for generation 2, repeat steps 3-10. Note: Because you will be starting with a very small population, extinction is a possibility, but the odds are against it. If your population does go extinct, start again. 12. Continue rolling the dice and recording data until your population size reaches a minimum of 100. www.HOLscience.com 9 ©Hands-On Labs, Inc. Experiment Population Ecology 13. Once you have reached a population size of 100, calculate the change in population size for each generation. Record each value in Data Table 1. Use the following equation: Change in population size = Final population size – Initial population size 14. Graph the initial population size for each generation. To do this, create a scatter plot with the generations on the independent axis (x-axis) and the initial population size on the dependent axis (y-axis). Consider whether the population growth you modeled showed a linear pattern, exponential pattern, or no pattern. 15. Resize the graph and insert it into Data Table 2 of your Lab Report Assistant. Refer to the appendix entitled, “Resizing an Image” for guidance with resizing an image. 16. Graph the change in population size for each generation. To do this, create a bar graph with the generations on the independent axis (x-axis) and the change in population size on the dependent axis (y-axis). Consider whether changes in population size were greatest when the population was smaller or larger. 17. Resize the graph and insert it into Data Table 3 of your Lab Report Assistant. Questions A. How many generations did it take to reach a population size of 100? B. Consider the mode of reproduction modeled in your population. Would sexual reproduction or asexual reproduction likely be the cause of a birth? Are individuals of the species likely or unlikely to have separate male and female sexes? C. Did the modeled population exhibit linear growth, exponential growth, or no pattern? Use Data Table 2 to support your answer. D. Were changes in population size greatest when the population was smaller or larger? Which generation exhibited the greatest change in size? Use Data Table 3 to support your answer. E. What resource constraints were placed on the modeled population? F. Could the modeled population exhibit indefinite growth? If so, how? Is indefinite growth observed in nature? Explain why or why not. www.HOLscience.com 10 ©Hands-On Labs, Inc. Experiment Population Ecology Exercise 2: Investigating a Human Population In this exercise, you will investigate demography of a human population. You will collect birth and death information from a cemetery and analyze trends in the population. 1. Research your local area to find a cemetery that you may visit for this exercise. Note: If you are unable to access a cemetery, you may use the data provided in the “HOL Supplied Cemetery Data” Supplemental Document. If you choose to do this, skip to step 8. 2. Print a copy of Data Table 4 from your Lab Report Assistant, to bring with you to the cemetery. Travel to a cemetery during the day, ensure that conditions are safe and public access is permitted. 3. In Data Table 4, record the name, birth date and date of death for 80 deceased individuals. As you collect data, be sure to spread out within the full sampling area. Individuals of the same family or who died in shared years will often be grouped together, and the goal is to take a representative sample of all individuals in the population. 4. Record the cemetery name and location in Data Table 4. 5. Determine how old each person was when they died, and record your data in Data Table 4. Use the following equation: Age at death = Birth year – Death year 6. Investigate the first names of each individual and record the sex (M for male; F for female) in Data Table 4. If the name is gender-neutral, such as Jean, Lynn, or Pat, you may leave the area blank. Ensure that any data you recorded by hand is present in the Lab Report Assistant document that you report to your instructor. Note: This concludes the outdoor portion of this exercise; the rest of Exercise 2 may be performed from home. 7. Record a summary of the population. Address each of the following questions, and record data in Data Table 5 of your Lab Report Assistant. ● What were the first and last birth years? ● What were the first and last death years? ● How many individuals died before 1950? How many died after 1950? ● How many individuals are male and female? www.HOLscience.com 11 ©Hands-On Labs, Inc. Experiment Population Ecology 8. In the next steps, you will calculate the probability of dying within a given cohort. As shown in Data Table 6 of your Lab Report Assistant, cohorts are age classes. For example, cohort 1 includes individuals that died between the ages of 1 and 9; cohort 2 includes individuals who died between the ages of 10 and 19. Examine Data Table 6 and study the following descriptions for each column heading: ● Cohort (X) – The age intervals of deceased individuals. ● Number of Deaths (D) – The number of individuals that died in each cohort. ● Frequency of Population in Cohort (d) – The portion of the population that died in each cohort. ● Frequency of Survivorship Entering the Cohort (l) – The portion of the population that enters the cohort. ● Probability of Death within a Cohort (Q ) – The probability that any given individual will die within a cohort. 9. Count the number of people who died in each cohort (age interval). Record your data under “Number of deaths (D)” in Data Table 6. 10. Calculate the “Frequency of population in cohort (d).” Record each value as a number with two decimal places. Use the following equation: d = D / Total Population Size Note: “Frequency of survivorship of cohort (l)” is based on entry into the cohort. Thus, the first cohort listed will always have a value of 1.00 because 100% of the population was born, entering into the cohort. A value of 1.00 has been entered for cohort # 1 in Data Table 6. With each subsequent cohort, values of “l” will decrease. 11. Calculate the “Frequency of survivorship of cohort (l)” for cohort # 2. Record each value as a number with 2 decimal places. Use the following equation: I cohort2 = Icohort1 – dcohort1 12. Calculate the “Frequency of survivorship of cohort (l)” for each of the remaining cohorts. For example, “Frequency of survivorship of cohort (l)” for cohort 3 will be calculated as: I cohort3 = Icohort2 – dcohort2 Note: The final recorded “l” in Data Table 6 should be equivalent or very close to the final recorded “d.” 13. Calculate the “Probability of death (Q).” Record each value as a number with 2 decimal places. Use the following equation: Q = d / l www.HOLscience.com 12 ©Hands-On Labs, Inc. Experiment Population Ecology Note: The probability of death is a frequency and may be interpreted as a percentage. For example, if Q=0.30 for cohort # 1, then there is a 30% probability that a given individual will die between the ages of 1 to 9. Note: To find Q, use data within a single cohort: Qcohort1 = dcohort1 / lcohort1 14. Create a bar graph of the probability of death within each cohort. Plot the cohort age interval (1-9, 10-19, etc.) on the independent axis (x-axis), and plot the probability of death on the dependent axis (y-axis). 15. Resize the graph and insert it into Data Table 7 of your Lab Report Assistant. 16. When you are finished uploading photos and data into your Lab Report Assistant, save your file correctly and zip the file so you can send it to your instructor as a smaller file. Refer to the appendix entitled “Saving Correctly” and the appendix entitled “Zipping Files” for guidance with saving the Lab Report Assistant correctly and zipping the file. Questions A. Which cohort had the greatest probability of death? Which had the least probability? Use the graph in Data Table 7 to support your answer. B. Overall, does human mortality tend to be greatest at young ages or older ages? C. How many individuals were male, and how many were female? How many individuals were you unable to assign a gender to? D. Using the raw data in Data Table 4, calculate the average age at death for males and for females. What inferences can you make about male versus female age at death? E. If the government made significant cuts in social services, such as prenatal and infant care, how might your data be affected? www.HOLscience.com 13 ©Hands-On Labs, Inc. Experiment Population Ecology Population Ecology Hands-On Labs, Inc. Version 42-0281-00-02 Lab Report Assistant This document is not meant to be a substitute for a formal laboratory report. The Lab Report Assistant is simply a summary of the experiment’s questions, diagrams if needed, and data tables that should be addressed in a formal lab report. The intent is to facilitate students’ writing of lab reports by providing this information in an editable file which can be sent to an instructor. Exercise 1: Modeling Population Growth See next page www.HOLscience.com 14 ©Hands-On Labs, Inc. Experiment Population Ecology Data Table 1. Population Growth Model. Generation Initial Population Size (N) Number of Births (B) Number of Deaths (D) Final Population Size (N + B – D) Change in Population Size (Final – Initial) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 www.HOLscience.com 15 ©Hands-On Labs, Inc. Experiment Population Ecology Data Table 2. Population Size and Generations: Scatter Plot. Population Size Data Table 3. Population Size and Generations: Bar Graph. Population Size www.HOLscience.com 16 ©Hands-On Labs, Inc. Experiment Population Ecology Questions A. How many generations did it take to reach a population size of 100? B. Consider the mode of reproduction modeled in your population. Would sexual reproduction or asexual reproduction likely be the cause of a birth? Are individuals of the species likely or unlikely to have separate male and female sexes? C. Did the modeled population exhibit linear growth, exponential growth, or no pattern? Use Data Table 2 to support your answer. D. Were changes in population size greatest when the population was smaller or larger? Which generation exhibited the greatest change in size? Use Data Table 3 to support your answer. E. What resource constraints were placed on the modeled population? F. Could the modeled population exhibit indefinite growth? If so, how? Is indefinite growth observed in nature? Explain why or why not. www.HOLscience.com 17 ©Hands-On Labs, Inc. Experiment Population Ecology Exercise 2: Investigating a Human Population Data Table 4. Raw Data for Deceased Individuals. Cemetery Name and Location: Individual First Name Last Name Birth Year Death Year Age at Death Sex (M/F) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 www.HOLscience.com 18 ©Hands-On Labs, Inc. Experiment Population Ecology 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 www.HOLscience.com 19 ©Hands-On Labs, Inc. Experiment Population Ecology 69 70 71 72 73 74 75 76 77 78 79 80 Data Table 5. Summary of Deceased Individuals. Observations Data First birth year Last birth year First death year Last death year Number of individuals who died before 1950 Number of individuals who died after 1950 Number of males Number of females www.HOLscience.com 20 ©Hands-On Labs, Inc. Experiment Population Ecology Data Table 6. Demography Data. # Cohort (X) Number of Deaths (D) Frequency of Population in Cohort (d) Frequency of Survivorship Entering the Cohort (l) Probability of Death within a Cohort (Q) 1 1-9 1.00 2 10-19 3 20-29 4 30-39 5 40-49 6 50-59 7 60-69 8 70+ Total 80 1.00 Data Table 7. Probability of Death within Each Cohort. Probability of Death www.HOLscience.com 21 ©Hands-On Labs, Inc. Experiment Population Ecology Questions A. Which cohort had the greatest probability of death? Which had the least probability? Use the graph in Data Table 7 to support your answer. B. Overall, does human mortality tend to be greatest at young ages or older ages? C. How many individuals were male, and how many were female? How many individuals were you unable to assign a gender to? D. Using the raw data in Data Table 4, calculate the average age at death for males and for females. What inferences can you make about male versus female age at death? E. If the government made significant cuts in social services, such as prenatal and infant care, how might your data be affected? www.HOLscience.com 22 ©Hands-On Labs, Inc. Experiment Population Ecology

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Biology Labs

November 11, 2023/in Uncategorized /by Daniel Jennings

Pre-Lab Questions

1. What are chromosomes made of?

2. Research the differences that exist between mitosis and binary fission. Identify at least one difference, and explain why it is significant.

3. Cancer is a disease related to uncontrolled cell division. Investigate two known causes for these rapidly dividing cells and use this knowledge to invent a drug that would inhibit the growth of cancer cells.

Experiment 1: Observation of Mitosis in a Plant Cell

In this experiment, we will look at the different stage of mitosis in an onion cell. Remember that mitosis only occupies one to two hours while interphase can take anywhere from 18 – 24 hours. Using this information and the data from your experiment, you can estimate the percentage of cells in each stage of the cell cycle.

Materials

Onion (allium) Root Tip Digital Slide Images

Procedure:

Part 1: Calculating Time Spent in Each Cell Cycle Phase

1. The length of the cell cycle in the onion root tip is about 24 hours. Predict how many hours of the 24 hour cell cycle you think each step takes. Record your predictions, along with supporting evidence, in Table 1.

2. Examine the onion root tip slide images on the following pages. There are four images, each displaying a different field of view. Pick one of the images, and count the number of cells in each stage. Then count the total number of cells in the image. Record the image you selected and your counts in Table 2.

3. Calculate the time spent by a cell in each stage based on the 24 hour cycle:

Hours of Stage =	24 x Number of Cells in Stage
	Total Number of Cells Counted

Part 2: Identifying Stages of the Cell Cycle

1. Observe the images of the root cap tip.

2. Locate a good example of a cell in each of the following stages: interphase, prophase, metaphase, anaphase, and telophase.

3. Draw the dividing cell in the appropriate area for each stage of the cell cycle, exactly as it appears. Include your drawings in Table 3.

Onion Root Tip: 100X

Table 1: Mitosis Predictions
Predictions:
Supporting Evidence:

Table 2: Mitosis Data
Number of Cells in Each Stage	Total Number of Cells	Calculated % of Time Spent in Each Stage
Interphase:		Interphase:
Prophase:		Prophase:
Metaphase:		Metaphase:
Anaphase:		Anaphase:
Telophase:		Telophase:
Cytokinesis:		Cytokinesis:

Table 3: Stage Drawings
Cell Stage:	Drawing:
Interphase:
Prophase:
Metaphase:
Anaphase:
Telophase:
Cytokinesis:

Post-Lab Questions

1. Label the arrows in the slide image below with the appropriate stage of the cell cycle.

2. In what stage were most of the onion root tip cells? Based on what you know about cell cycle division, what does this imply about the life span of a cell?

3. Were there any stages of the cell cycle that you did not observe? How can you explain this using evidence from the cell cycle?

4. As a cell grows, what happens to its surface area to volume ratio? (Hint: Think of a balloon being blown up). How does this ratio change with respect to cell division?

5. What is the function of mitosis in a cell that is about to divide?

6. What would happen if mitosis were uncontrolled?

7. How accurate were your time predication for each stage of the cell cycle?

8. Discuss one observation that you found interesting while looking at the onion root tip cells.

Experiment 2: Tracking Chromosomal DNA Movement through Mitosis

Although mitosis and meiosis share similarities, they are different processes and create very different results. In this experiment, you will follow the movement of the chromosomes through mitosis to create somatic daughter cells.

Materials

2 Sets of Different Colored Pop-it® Beads (32 of each – these may be any color) (8) 5-Holed Pop-it® Beads (used as centromeres)

Procedure

Genetic content is replicated during interphase. DNA exists as loose molecular strands called chromatin; it has not condensed to form chromosomes yet.

Sister chromatids begin coiling into chromosomes during prophase. Begin your experiment here:

1. Build a pair of replicated, homologous chromosomes. 10 beads should be used to create each individual sister chromatid (20 beads per chromosome pair). Two five-holed beads represent each centromere. To do this…

Figure 5: Bead set-up. The blue beads represent one pair of sister chromatids and the black beads represent a second pair of sister chromatids. The black and blue pair are homologous.

a. Start with 20 beads of one color to create your first sister chromatid pair. Five beads must be snapped together for each of the four different strands. Two strands create the first chromatid, and two strands create the second chromatid.

b. Place one five-holed bead flat on a work surface with the node positioned up. Then, snap two of the four strands into the bead to create an “I” shaped sister chromatid. Repeat this step with the other two strands and another five-holed bead.

c. Once both sister chromatids are constructed, connect them by their five-holed beads creating an “X” shape.

d. Repeat this process using 20 new beads (of a different color) to create the second sister chromatid pair. See Figure 5 for reference.

2. Assemble a second pair of replicated sister chromatids; this time using 12 beads, instead of 20, per pair (six beads per each complete sister chromatid strand).

Figure 6: Second set of replicated chromosomes.

3. Repeat this process using 12 new beads (of a different color) to create the second set of sister chromatids. See Figure 6 for reference.

4. Configure the chromosomes as they would appear in each of the stages of the cell cycle (prophase, metaphase, anaphase, telophase, and cytokinesis). Diagram the images for each stage in the section titled “Cell Cycle Division: Mitosis Beads Diagram”. Be sure to indicate the number of chromosomes present in each cell for each phase.

Cell Cycle Division: Mitosis Beads Diagram:

Prophase

Metaphase

Anaphase

Telophase

Cytokinesis

Post-Lab Questions

1. How many chromosomes did each of your daughter cells contain?

2. Why is it important for each daughter cell to contain information identical to the parent cell?

3. How often do human skin cells divide? Why might that be? Compare this rate to how frequently human neurons divide. What do you notice?

4. Hypothesize what would happen if the sister chromatids did not split equally during anaphase of mitosis.

Experiment 3: The Importance of Cell Cycle Control

Some environmental factors can cause genetic mutations which result in a lack of proper cell cycle control (mitosis). When this happens, the possibility for uncontrolled cell growth occurs. In some instances, uncontrolled growth can lead to tumors, which are often associated with cancer, or other biological diseases.

In this experiment, you will review some of the karyotypic differences which can be observed when comparing normal, controlled cell growth and abnormal, uncontrolled cell growth. A karyotype is an image of the complete set of diploid chromosomes in a single cell.

Materials

*Computer Access *Internet Access

*You Must Provide

Procedure

1. Begin by constructing a hypothesis to explain what differences you might observe when comparing the karyotypes of human cells which experience normal cell cycle control versus cancerous cells (which experience abnormal, or a lack of, cell cycle control). Record your hypothesis in Post-Lab Question 1. Note: Be sure to include what you expect to observe, and why you think you will observe these features. Think about what you know about cancerous cell growth to help construct this information

2. Go online to find some images of abnormal karyotypes, and normal karyotypes. The best results will come from search terms such as “abnormal karyotype”, “HeLa cells”, “normal karyotype”, “abnormal chromosomes”, etc. Be sure to use dependable resources which have been peer-reviewed

3. Identify at least five abnormalities in the abnormal images. Then, list and draw each image in the Data section at the end of this experiment. Do these abnormalities agree with your original hypothesis? Hint: It may be helpful to count the number of chromosomes, count the number of pairs, compare the sizes of homologous chromosomes, look for any missing or additional genetic markers/flags, etc.

Data

Post-Lab Questions

1. Record your hypothesis from Step 1 in the Procedure section here.

2. What do your results indicate about cell cycle control?

3. Suppose a person developed a mutation in a somatic cell which diminishes the performance of the body’s natural cell cycle control proteins. This mutation resulted in cancer, but was effectively treated with a cocktail of cancer-fighting techniques. Is it possible for this person’s future children to inherit this cancer-causing mutation? Be specific when you explain why or why not.

Pre-Lab Questions

1. Arrange the following molecules from least to most specific with respect to the original nucleotide sequence: RNA, DNA, Amino Acid, Protein

2. Identify two structural differences between DNA and RNA.

3. Suppose you are performing an experiment in which you must use heat to denature a double helix and create two single stranded pieces. Based on what you know about nucleotide bonding, do you think the nucleotides will all denature at the same time? Use scientific reasoning to explain why.

Experiment 1: Coding

In this experiment, you will model the effects of mutations on the genetic code. Some mutations cause no structural or functional change to proteins while others can have devastating affects on an organism.

Materials

Red Beads

Blue Beads

Yellow Beads

Green Beads

Procedure:

1. Using the red, blue, yellow and green beads, devise and lay out a three color code for each of the following letters (codon). For example Z = green : red : green.

In the spaces below the letter, record your “code”.

C:	E:	H:	I:	K:	L:
bbb	ggg	rrr	yyy	bgr	Grb

M:	O:	S:	T:	U:
yrg	yby	byb	Rgr	Gyg

Create codons for:	Start:	Stop:	Space:
	bbr	ggr	yyr

2. Using this code, align the beads corresponding to the appropriate letter to write the following sentence (don’t forget start, space and stop): The mouse likes most cheese

a. How many beads did you use? 87

There are multiple ways your cells can read a sequence of DNA and build slightly different proteins from the same strand. We will not go through the process here, but as an illustration of this “alternate splicing”, remove codons (beads) 52 – 66 from your sentence above.

b. What does the sentence say now? (re-write the entire sentence) The mouse likes cheese

Mutations are simply changes in the sequence of nucleotides. There are three ways this occurs:

1. Change a nucleotide(s)

2. Remove a nucleotide(s)

3. Add a nucleotide(s)

3. Using the sentence from exercise 1B:

a. Change the 24th bead to a different color. What does the sentence say now (re-read the entire sentence)? Does the sentence still make sense?

The moose likes cheese

b. Replace the 24th bead and remove the 20th bead (remember what was there). What does the sentence say (re-read the entire sentence)? Does the sentence still make sense? If it doesn’t make sense as a sentence, are there any words that do? If so, what words still make sense?

The muse likes cheese

c. Replace the 20th bead and add one between bead numbers 50 and 51. What does the sentence say now? Does the sentence still make sense?

d. In 3.a (above) you mutated one letter. What role do you think the redundancy of the genetic code plays in this type of change?

e. Based on your observations, why do you suppose the mutations we made in 3.b and 3.c are called frame shift mutations?

f. Which mutations do you suspect have the greatest consequence? Why?

Experiment 2: Transcription and Translation

DNA codes for all of the proteins manufactured by any organism (including you!). It is valuable, highly informative and securely protected in the nucleus of every cell. Consider the following analogy:

An architect spends months or years designing a building. Her original drawings are valuable and informative. She will not provide the original copy to everyone involved in constructing the building. Instead, she gives the electrician a copy with the information she needs to build the electrical system. She will do the same for the plumbers, the framers, the roofers and everyone else who needs to play a role to build the structure. These are subsets of the information contained in the original copy. Your cell does the same thing. The “original drawings” are contained in your DNA which is securely stored in the nucleus.

Nuclear DNA is “opened up” by an enzyme called helicase, and a subset of information is transcribed into RNA. RNA is a single strand version of DNA, where the nucleotide uracil, replaces thymine. The copies are sent from the nucleus to the cytoplasm in the form of messenger RNA (mRNA ). Once in the cytoplasm, transfer RNA (tRNA) links to the codons and aligns the proper amino acids, based on the mRNA sequence. Protein builders called ribosomes float around in the cytoplasm, latch onto the strand of mRNA and sequentially link the amino acids together that the tRNA has lined up for them. This construction of proteins from the mRNA is known as translation.

Materials

Blue beads Green beads Red beads Yellow beads Pop-it® beads (8 different colors) *Pen or pencil

*You Must Provide In this experiment:

· Regular beads are used as nucleotides.

· Pop-it® beads are used as amino acids.

Procedure

1. Use a pen or pencil to write a five word sentence using no more than eight different letters in the space below.

2. Now, use the red, blue, green, and yellow beads to form “codons” (three beads) for each letter in your sentence. Then, create codons to represent the “start, “space” and stop” regions within your sentence. Write the sentence using the beads in the space below:

3. How many beads did you use?

4. Assign one Pop-It® bead to represent each codon. You do not need to assign a Pop-It® bead for the start, stop and space regions. These will be your amino acids.

5. Connect the Pop-It® beads to build the chain of amino acids that code for your sentence (leave out the start, stop, and space regions).

6. How many different amino acids did you use?

7. How many total amino acids did you use?

Experiment 3: DNA Extraction

Much can be learned from studying an organism’s DNA. The first step to doing this is extracting DNA from cells. In this experiment, you will isolate DNA from the cells of fruit.

Materials

(1) 10 mL Graduated Cylinder (2) 100 mL Beakers 15 cm Cheesecloth 1 Resealable Bag 1 Rubber Band (Large. Contains latex; please wear gloves when handling if you have a latex allergy). Standing Test Tube Wooden Stir Stick *Fresh, Soft Fruit (e.g., Grapes, Strawberries, Banana, etc.)

*Scissors **DNA Extraction Solution ***Ice Cold Ethanol *You Must Provide **Contains sodium chloride, detergent and water ***For ice cold ethanol, store in the freezer 60 minutes before use.

REMINDER: You are REQUIRED to video yourself performing steps 3 through 9 of the procedure below. You MUST submit the video with the lab to receive credit for this experiment.

Procedure:

1. If you have not done so, prepare the ethanol by placing it in a freezer for approximately 60 minutes.

2. Put pieces of a soft fruit into a plastic zipper bag and mash with your fist. The amount of food should be equal to the size of approximately five grapes.

3. Use the 10 mL graduated cylinder to measure 10 mL of the DNA Extraction Solution. Transfer the solution from the cylinder to the bag with the fruit it in. Seal the bag completely.

4. Mix well by kneading the bag for two minutes.

5. Create a filter by placing the center of the cheesecloth over the mouth of the standing test tube, pushing it into the tube about two inches, and securing the cheesecloth with a rubber band around the top of the test tube.

6. Cut a hole in the corner of the bag and filter your extraction by pouring it into the cheesecloth. You will need to keep the filtered solution which passes through the cheese cloth into the standing test tube.

7. Rinse the 10 mL graduated cylinder, and measure five mL of ice-cold ethanol. Then, while holding the standing test tube at a 45° angle, slowly transfer the ethanol into the standing test tube with the filtered solution.

Figure 6: DNA extraction. The color has been enhanced by dying the fruit with a substance that glows under black light.

8. DNA will precipitate (come out of solution) after the ethanol has been added to the solution. Let the test tube sit undisturbed for 2 – 5 minutes. You should begin to see air bubbles form at the boundary line between the ethanol and the filtered fruit solution. Bubbles will form near the top, and you will eventually see the DNA float to the top of the ethanol.

9. Gently insert the stir stick into the test tube. Slowly raise and lower the tip several times to spool and collect the DNA. If there is an insufficient amount of DNA available, it may not float to the top of the solution in a form that can be easily spooled or removed from the tube. However, the DNA will still be visible as white/clear clusters by gently stirring the solution and pushing the clusters around the top.

Post-Lab Questions

1. What is the texture and consistency of the DNA?

2. Why did we use a salt in the extraction solution?

3. Is the DNA soluble in the aqueous solution or alcohol?

4. What else might be in the ethanol/aqueous interface? How could you eliminate this?

5. Which DNA bases pair with each other? How many hydrogen bonds are shared by each pair?

6. How is information to make proteins passed on through generations?

Pre-Lab Questions

1. In a species of mice, brown fur color is dominant to white fur color. When a brown mouse is crossed with a white mouse all of their offspring have brown fur. Why did none of the offspring have white fur?

2. Can a person’s genotype be determine by their phenotype? Why or why not?

3. Are incomplete dominant and co-dominant patterns of inheritance found in human traits? If yes, give examples of each.

4. Consider the following genotype: Yy Ss Hh. We have now added the gene for height: Tall (H) or Short (h).

a. How many different gamete combinations can be produced?

b. Many traits (phenotypes), like eye color, are controlled by multiple genes. If eye color were controlled by the number of genes indicated below, how many possible genotype combinations would there be in the following scenarios?

5 Eye Color Genes:

10 Eye Color Genes:

20 Eye Color Genes:

Experiment 1: Punnett Square Crosses

In this experiment you will use monohybrid and dihybrid crosses to predict patterns of inheritance.

Materials

Blue Beads Green Beads Red Beads

Yellow Beads (2) 100 mL Beakers Permanent Marker

Procedure:

Part 1: Punnett Squares

1. Set up and complete Punnett squares for each of the following crosses: (remember Y = yellow, and y = blue)

Y Y and Y y

Y Y and y y

2. What are the resulting phenotypes?

3. Are there any blue kernels? How can you tell?

4. Set up and complete a Punnett squares for a cross of two of the F1 from Step 1 (above).

5. What are the genotypes of the F2 generation?

6. What are their phenotypes?

7. Are there more or less blue kernels than in the F1 generation?

8. Identify the four possible gametes produced by the following individuals:

a)	YY Ss:	______	______	______	______
b)	Yy Ss:	______	______	______	______
c)	Create a Punnett square using these gametes as P and determine the genotypes of the F1:

What are the phenotypes? What is the ratio of those phenotypes?

Part 2 and 3 Setup

1. Use the permanent marker to label the two 100 mL beakers as “1” and “2”.

2. Pour 50 of the blue beads and 50 of the yellow beads into Beaker 1. Sift or stir the beads around to create a homogenous mixture.

3. Pour 50 of the red beads and 50 of the green beads into Beaker 2. Sift or stir the beads around to create a homogenous mixture.

Assumptions for the remainder of the experiment:

· Beaker 1 contains beads that are either yellow or blue.

· Beaker 2 contains beads that are either green or red.

· Both beakers contain approximately the same number of each colored bead.

· These colors correspond to the following traits (remember that Y/y is for kernel color and S/s is for smooth/wrinkled):

1. Yellow (Y) vs. Blue (y)

2. Green (G) vs. Red (g).

Part 2: Monohybrid Cross

1. Randomly (without looking) take two beads out of Beaker 1. This is the genotype of Individual #1. Record the genotype in Table 1. Do not put these beads back into the beaker.

Table 1: Parent Genotypes: Monohybrid Crosses
Generation	Genotype of Individual 1	Genotype of Individual 2
P
P1
P2
P3
P4

2. Repeat Step 1 for Individual #2. These two genotypes represent the parents (generation P) for the next generation.

3. Set up a Punnett square and determine the genotypes and phenotypes for this cross. Record your data in Table 2

4. Repeat Step 3 four more times (for a total of five subsequent generations). Return the beads to their respective beakers when finished.

Table 2: Generation Data Produced by Monohybrid Crosses
Parents	Possible Offspring Genotypes	Possible Offspring Phenotypes	Genotype Ratio	Phenotype Ratio
P
P1
P2
P3
P4

Post-Lab Questions

Part 2: Monohybrid Cross

1. How much genotypic variation do you find in the randomly picked parents of your crosses?

2. How much in the offspring?

3. How much phenotypic variation?

4. Is the ratio of observed phenotypes the same as the ratio of predicted phenotypes? Why or why not?

5. Pool all of the offspring from your five replicates. How much phenotypic variation do you find?

6. What is the difference between genes and alleles?

7. How might protein synthesis execute differently if a mutation occurs?

8. Organisms heterozygous for a recessive trait are often called carriers of that trait. What does that mean?

9. In peas, green pods (G) are dominant over yellow pods. If a homozygous dominant plant is crossed with a homozygous recessive plant, what will be the phenotype of the F1 generation? If two plants from the F1 generation are crossed, what will the phenotype of their offspring be?

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Human Genetics

November 11, 2023/in Uncategorized /by Daniel Jennings

[Type text] [Type text] [Type text]

Please answer each question fully and in complete sentences. You may use textbook, or PowerPoint slides, and resources indicated in the questions below; if you use other resources, they must be cited properly in a working bibliography (author, article title, journal or book title, date of publication, page numbers)

Topic 8: Multifactorial and Acquired Developmental Traits

Should a woman be held legally responsible if she drinks alcohol, smokes, or abuses drugs during pregnancy and it harms her child (e.g., fetal alcohol syndrome)? If so, should liability apply to all substances that can harm a fetus, or only to those that are illegal? For example, we know that maternal weight gain in pregnancy is associated with an increased risk for diabetes in their children. What evidence or reasoning leads you to this opinion? State your opinion and then give sound reasoning for it.)

Topic 9: Multifactorial and Acquired Cancer Traits

Many genes contribute to lung cancer risk, especially among people who smoke tobacco. These genes include p53, IL1A, IL1B, CYP1A1, EPHX1, TERT, and CRR9. Search for one of these genes online and describe how mutations in the gene may contribute to causing lung cancer, or how polymorphisms in the gene may be associated with increased risk in combination with smoking. Be sure to choose a trustworthy source and cite the source with your answer.

Topic 10: Acquired Microbiome Traits

Malnutrition is common among children in the African nation of Malawi. Researchers hypothesized that the microbiome may play a role in starvation because in some families, some children are malnourished and their siblings are not, even though they eat the same diet. Even identical twins may differ in nutritional status.

Researchers followed 317 sets of twins in Malawi, from birth until age 3. In half of the twin pairs, one or both twins developed kwashiorkor, the type of protein malnutrition that swells bellies. The researchers focused on twin pairs in which only one was starving, including both identical and fraternal pairs. At the first sign that one twin was malnourished, both were placed on a diet of healthy “therapeutic food.” Four weeks later, the pair returned to the nutrient-poor village diet. If the malnourished twin became so again, then the researchers compared his or her microbiome to that of the healthy sibling. The goal was to identify bacterial species that impair the ability of a child to extract nutrients from the native diet. [Smith, et al. (2013) Gut microbiomes of Malawian twin pairs discordant for kwashiorkor. Science 339(6119):548-554.]

How might the findings from this study be applied to help prevent or treat malnutrition? Do you think that the study was conducted ethically? Why or why not? Explain how identical twins who follow the same diet can differ in nutritional status.

Topic 11: Multifactorial and Acquired Epigenetic Traits

The environmental epigenetics hypothesis states that early negative experiences, such as neglect, abuse, and extreme stress, increase the risk of developing depression, anxiety disorder, addictions, and/or obesity later in life through effects on gene expression that persist and can be passed on to the next generation. Suggest an experiment to test this hypothesis.

Topic 12: Genetics of Human Populations: Hardy-Weinberg Equilibrium

Population bottlenecks are evident today in Arab communities, Israel, India, Thailand, Scandinavia, some African nations, and especially among indigenous peoples such as Native Americans. Research an indigenous or isolated population and describe a genetic condition that its members have that is rare among other groups of people, and how the population bottleneck occurred.

Topic 13: Human Evolution

Explain why analyzing mitochondrial DNA or Y chromosome DNA cannot provide a complete picture of an individual’s ancestry. How can a female trace her paternal lineage if she does not have a Y chromosome?

Topic 14: Biotechnology in Human Genetic Research

Go to clinicaltrials.gov and search under “gene therapy.” Describe one of the current research trials for correcting a genetic problem. Include information about the genetic condition if available, including: mode of inheritance, age of onset, symptom severity, variability in expression, existing treatments (standard of care), and how the gene therapy is proposed to correct the problem.

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Biology 1334 Lab Assignment #2

November 11, 2023/in Uncategorized /by Daniel Jennings

DNA and Protein Synthesis Hands-On Labs, Inc. Version 42-0051-00-02

Review the safety materials and wear goggles when working with chemicals. Read the entire exercise before you begin. Take time to organize the materials you will need and set aside a safe work space in which to complete the exercise.

Experiment Summary:

You will learn the structure and function of DNA and RNA. You will learn the similarities and differences between DNA and RNA. You will learn the process of protein synthesis and create and use models to demonstrate both transcription and translation.

EXPERIMENT

Learning Objectives Upon completion of this laboratory, you will be able to:

● Review the structure and function of DNA.

● Identify the codons that code for amino acids in DNA and RNA.

● Explain the purpose of start and stop codons in protein synthesis.

● Summarize the steps involved in protein synthesis and define a ribosome and its three sites.

● Summarize the steps of transcription, including: initiation, elongation, and termination.

● Summarize the steps of translation, including; initiation, elongation, and termination.

● Illustrate and model the processes of transcription and translation.

● Construct a series of tRNA molecules and write the anti-codons and amino acids each tRNA carries.

● Explain the difference in the number of amino acids that were present at the start and at the end of the translation model.

Time Allocation: 3 hours

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Experiment DNA and Protein Synthesis

Materials Student Supplied Materials

Quantity Item Description 1 Camera, digital or Smartphone 1 Pair of scissors 1 Printer

10 Sheets of printer paper 1 Pen or pencil 1 Tape

HOL Supplied Materials

Quantity Item Description 1 DNA Nucleotide Template 1 RNA Nucleotide Template 1 tRNA Template

Note: To fully and accurately complete all lab exercises, you will need access to:

1. A computer to upload digital camera images.

2. Basic photo editing software such as Microsoft Word® or PowerPoint®, to add labels, leader lines, or text to digital photos.

3. Subject-specific textbook or appropriate reference resources from lecture content or other suggested resources.

Note: The packaging and/or materials in this LabPaq kit may differ slightly from that which is listed above. For an exact listing of materials, refer to the Contents List included in your LabPaq kit.

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Experiment DNA and Protein Synthesis

Background DNA, Codons, and Proteins

Deoxyribonucleic acid (DNA), the genetic material of all living organisms, is composed of two chains of nucleotides wound together in a double-helical formation. Nucleotides, the molecules responsible for the structural units of DNA, are composed of three sections: a phosphate group (PO4), a sugar (deoxyribose) group, and a nitrogenous base. There are four different DNA nucleotides: adenine (A), thymine (T), cytosine (C), and guanine (G), which are identical in their phosphate and sugar groups, but vary in their nitrogenous bases. The bonds between the sugar and phosphate groups of each nucleotide form the sugar-phosphate backbone of DNA and the two strands wind together as a result of base pairing: AT (Adenine-Thymine) or GC (Guanine- Cytosine).

The arrangement of the four DNA nucleotides creates the genetic code, the blueprint for all living things. The genetic code is composed of codons, triplets of nucleotides that contain the code for the production of amino acids, which are strung together to create proteins (polypeptide chains). Proteins are highly complex, organic substances that provide a vast number of functions in living organisms, including maintenance of cells and growth. Thus, proteins are essential components of living tissues including: skin, bones, and muscle. The four different nucleotides provide 64 different codons (four options for each of three positions = 43 = 64 options), which code for one of twenty amino acids or a stop codon. See Table 1.

Table 1. Codon Chart (DNA)

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Experiment DNA and Protein Synthesis

Protein Biosynthesis and Transcription

Protein biosynthesis is the process where cells use the genetic code to build proteins. The process differs slightly between prokaryotes (single-celled organism with no organelles or distinct nucleus) and eukaryotes (single or multi-celled organisms with organelles and DNA contained in a distinct nucleus). In the context of this experiment, the focus will be on the main steps and commonalities between the prokaryotic and eukaryotic protein biosynthesis steps. There are two main steps in protein biosynthesis: transcription and translation.

Transcription is the process by which single stranded RNA is synthesized from DNA. RNA (ribonucleic acid), like DNA, is composed of nucleotides with a phosphate, a sugar (ribose), and one of four nitrogenous bases. The nucleotides adenine, cytosine, and guanine exist in both DNA and RNA, however; in RNA, the nucleotide uracil (U) replaces thymine (T), and binds with adenine (A). See Figure 1.

Figure 1. Nitrogenous bases in DNA and RNA. Note that while DNA is double-stranded, RNA exists as a single-strand. © udaix

There are three steps in transcription: initiation, elongation, and termination. A general depiction of transcription is shown in Figure 2.

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Experiment DNA and Protein Synthesis

Figure 2. General schematic of transcription. © The National Human Genome Research Institute

In initiation, an enzyme called RNA polymerase binds to the DNA promoter, which is the DNA sequence that initiates transcription. The RNA polymerase causes the two strands of DNA to begin unwinding and separate from one another. In elongation, the RNA polymerase travels downstream (3’ to 5’) along the DNA antisense strand, elongating the mRNA transcript in the 5’ to 3’ direction. The DNA antisense strand is the template strand from which the mRNA is transcribed. Figure 2 illustrates how transcription creates an mRNA copy of the DNA sense, or coding, strand, with uracil replacing thymine in the newly constructed mRNA. As the RNA polymerase continues to move downstream, the two strand of DNA re-wind into a double-helix formation. In termination, the RNA polymerase detaches from the DNA and releases the transcribed mRNA. In a prokaryote, the released mRNA is complete and ready to move into translation, while in a eukaryote the released RNA undergoes a series of steps where it is processed before moving into translation as mRNA.

Translation

Translation, the second main step of protein synthesis, is the process by which the mRNA (created in transcription) is converted into a protein. In a prokaryote, translation occurs in the cytoplasm, the same site as transcription; while in eukaryotes, translation occurs in the cytoplasm, where it is carried after transcription has completed in the nucleus. There are two major players in translation; transfer RNA (tRNA) and ribosomes. tRNA is a clover-shaped molecule that acts as the interpreter between mRNA and the protein it will help to synthesize. A ribosome is an organelle which functions as the site of protein synthesis. Ribosomes are made of ribosomal RNA (rRNA) and protein molecules, and are divided into two subunits: large and small. The small ribosomal

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Experiment DNA and Protein Synthesis

subunit binds the mRNA and reads the information contained in the mRNA nucleotide sequence. The large ribosomal subunit contains three binding sites: the peptidyl-tRNA site (P site), the aminoacyl-tRNA site (A site), and the exit site (E site). See Figure 3.

Figure 3. The ribosome.

There are three steps in translation: activation and initiation, elongation, and termination. A general depiction of translation is shown in Figure 4.

Figure 4. General schematic of translation.

In the first step of translation, activation and initiation, the mRNA is threaded between the

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Experiment DNA and Protein Synthesis

small and large subunits of the ribosome. The ribosome signals the start of translation when it encounters and binds to the first start codon (AUG, which codes for the amino acid methionine) at the A site. The tRNA carrying the anticodon (UTC) and the methionine binds to the mRNA codon at the ribosomal A site, creating the initiation complex, signaling translation to begin. The tRNA bound mRNA then moves into the P site, which brings in the next tRNA carrying the complementary anticodon and amino acid to the mRNA now in the A site.

The amino acid in the P site then forms a peptide bond with the amino acid in the A site, releasing the amino acid from the tRNA in the P site and moving the empty tRNA into the E site. Simultaneously, the tRNA in the A site, holding the two peptide-bonded amino acids, then moves into the P site, signaling the next tRNA to bind to the mRNA in the A site. Using Figure 4 as an example, as the empty tRNA (which had been carrying valine) exits the E site, a peptide bond is formed between lysine (in the P site) and cysteine (in the A site). The lysine (peptide bound to valine, glutamate, serine, and glycine) then detaches from the tRNA in the P site and attaches to the tRNA in the A site. The tRNA in the A site (now carrying the cysteine, lysine, valine, glutamate, serine, and glycine) then moves into the P site, releasing the tRNA that had carried the lysine from the E site. As the tRNA is released from the E site, tRNA carrying the anticodon AUA and the amino acid tyrosine (yellow Tyr) binds to the mRNA in the A site, continuing the process. This continuous process, called elongation, builds the polypeptide chain (protein) one amino acid at a time until the mRNA reads a stop codon (UAA, UAG, or UGA).

When a stop codon is encountered in the mRNA at the A site, termination is signaled. In termination the stop codon signals the end of elongation, which cleaves the protein from the tRNA, allowing it to exit the ribosome. The two ribosome subunits and the mRNA then dissociate from one another, completing the translation process. The protein then undergoes a series of steps including post-translational modifications and protein folding to assume its new shape.

In 2009, Dr. Ada Yonath won the Nobel Prize in Chemistry. She was the first woman to win the Nobel Prize in Chemistry

in 45 years, since Dorothy Crowfoot Hodgkin in 1964, and the first woman in the Middle East to ever win the Chemistry Nobel Prize. Her award,

shared with Dr. Thomas Steitz and Dr. Venkatraman Ramakrishnam, was the result of her work on the

structural determination of the ribosome, determining the structure of both the small and large ribosomal

subunits. Her work lead to the conclusion that a ribosome is a ribozyme (ribonucleic acid enzyme), that

organizes its substrates in the stereochemistry necessary for the formation of peptide bonds. From her work came the new and exciting crystallization technique called cryo bio-crystallography, which allows for the crystallization of large biological macromolecules at cryogenic temperatures (approximately -320°F)

allowing the macromolecules to maintain their solution state.

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Experiment DNA and Protein Synthesis

Exercise 1: Protein Synthesis In this exercise, you will model the steps of protein synthesis, starting with a single strand of nucleotides and ending with a protein.

1. Print 6 copies of the DNA Nucleotide Template, 4 copies of the RNA Nucleotide Template, and 1 copy of the tRNA Template. It is preferable, but not necessary, to print them in color. The templates are located in the “Supplemental Documents” folder of your digital courseware.

2. Review the coding strand of DNA (5’ to 3’) in Data Table 1 of your Lab Report Assistant.

3. Create the template strand of DNA (3’ to 5’) and record in Data Table 1.

4. Gather the scissors, tape, and the 6 printed copies of the DNA Nucleotide Template. Cut out the nucleotides from the template. It is not necessary to cut out the entire nucleotide; rather, cut the nucleotide in a rectangular shape, only cutting out the details of the nitrogenous bases. See Figure 5.

Figure 5. Cutting out DNA nitrogenous bases.

5. Using the DNA nucleotides, create the entire double strand of DNA by matching up and taping together the base pairs. See Figure 6 as an example.

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Experiment DNA and Protein Synthesis

Figure 6. Pairing of DNA nucleotides.

6. Take a photograph of the completed double strand of DNA with your name and the data showing in the photograph. Resize and insert the photograph into Data Table 2 of your Lab Report Assistant. Refer to the appendix entitled “Resizing an Image” for guidance with resizing an image.

7. Determine the mRNA strand that transcription would produce from the DNA template strand and record the mRNA strand in Data Table 1.

8. Gather the 4 printed copies of the RNA Nucleotide Template. Cut out the nucleotides from the template. It is not necessary to cut out the entire nucleotide; rather, cut the nucleotide in a rectangular shape, only cutting out the details of the nitrogenous bases.

9. Using the RNA nucleotides, create the mRNA strand by matching up and taping together the base pairs.

10. Take a photograph of the mRNA strand with your name and the date showing in the photograph. Resize and insert the photograph in Data Table 2.

11. Starting with the first mRNA nucleotide, determine what amino acids the codons in the mRNA are coding for and record in Data Table 1.

Note: Use Table 2 to determine the amino acids coded by RNA codons.

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Experiment DNA and Protein Synthesis

Table 2. Codon Chart (RNA)

12. Gather the printed copy of the tRNA Template and cut out the tRNAs.

13. Build the line of tRNAs that would flow into the A site during translation. Write the anti- codons into each tRNA and the amino acid the mRNA codes for. See Figure 7 as an example of the tRNA that would be created from the mRNA codons CCU.

Note: Use Figure 4 in the Background section as needed to help organize your thoughts and identify where in the mRNA strand translation would begin.

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Experiment DNA and Protein Synthesis

Figure 7. tRNA created from mRNA (CCU). Note that the anti-codons (GGA) and the name of the amino acid (gly = glycine) are written into the tRNA.

14. Take a photograph of the tRNAs (in order) with your name and the date showing in the photograph. Resize and insert the photograph in Data Table 2.

15. Write the name of the each amino acid in the final protein created from translation and record in Data Table 1.

16. When you are finished uploading photos and data into your Lab Report Assistant, save your file correctly and zip the file so you can send it to your instructor as a smaller file. Refer to the appendix entitled “Saving Correctly” and the appendix entitled “Zipping Files” for guidance with saving the Lab Report Assistant correctly and zipping the file.

Note: Use a textbook or internet source, as necessary, for a list of the three-letter amino acid abbreviations and the full amino acid names.

Questions A. How many amino acids were coded for by the mRNA? How many amino acids were present

in the final protein chain created in translation? In detail, explain the differences in the two numbers; why were some amino acids coded for by the mRNA but not present in the final protein chain? What amino acids were omitted from the final protein chain? Explain your answers.

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Experiment DNA and Protein Synthesis

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Survey Of Life Science BIO

November 11, 2023/in Uncategorized /by Daniel Jennings

Chapter 1: Learning about Life

Name ________________________ Period _________

Chapter 1: Learning about Life

Guided Reading Activities

Chapter Content: The Scientific Study of Life

Complete the following questions as you read the first chapter content—The Scientific Study of Life:

1. is the study of life.

2. Jane Goodall is famous for her research on chimpanzees. Dr. Goodall observed the chimpan- zees for long periods of time and made numerous observations of them that she recorded very carefully. Which stage of scientific inquiry is this considered?

A) Exploration

B) Testing

C) Making a hypothesis

D) Drawing a conclusion

3. Use the following figure to answer this question. Assume your results reject your initial hypothesis as indicated. Briefly explain why you would not return to the exploration portion of the process to change the question instead of revising the hypothesis.

Hypothesis

The remote’s batteries are dead.

TESTING • Forming hypotheses • Making predictions • Running experiments • Gathering data • Interpreting data • Drawing conclusions

Prediction

If I replace the batteries, the

remote will work.

Experiment

I replace the batteries with

new ones.

Experiment does not support

hypothesis; revise hypothesis or

pose new one.

Experiment supports hypothesis;

make additional predictions

and test them.

Revise

EXPLORATION

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Chapter 1: Learning about Life

4. Match the following terms with the best definition: data, science, hypothesis, experiments, and peer review

Scientific tests where conditions can be controlled:

A tentative explanation for a set of observations:

A thorough review of scientific results prior to publication:

Inquiry into how the natural world functions:

Recorded observations:

5. The following figure indicates that the testing and communication components of science connect to each other. Briefly explain how these two components interact to strengthen each other. Hint—think back to peer review

6. An often misunderstood concept is the difference between a scientific theory and a hypothesis. Briefly explain what you would tell a student who believes a scientific theory and a hypothesis are the same.

EXPLORATION • Making observations • sking uestions • eeking information

TESTING • Forming hypotheses • Making predictions • Running experiments • Gathering data • Interpreting data • Drawing conclusions

COMMUNICATION • haring data • btaining feedback • ublishing papers • Replicating findings • uilding consensus

OUTCOMES • uilding knowledge • olving problems • Developing new technologies • enefiting society

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Chapter 1: Learning about Life

7. Use the following table to compare a control group to an experimental group.

Control group Experimental group Description

8. On page 8 of your textbook the authors describe an experiment in which the amount of butter is changed between two cookie recipes. Imagine a scenario in which a person also changes the type of flour used (whole wheat flour versus regular bleached flour). Is this still an effective controlled experiment? Briefly explain your answer either way.

9. Use the following figure to answer this question. By day 8 how far have the baby turtles traveled?

10. How many factors does a scientist want to differ between the experimental and control groups?

A) 2

B) 0

C) 1

D) 3

250

200

150

100

Days after release

D is

ta nc

e tr

av el

ed (k

m )

0 14128 10642

Key

Average of 24 green sea turtles verage of oating buckets

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Chapter 1: Learning about Life

11. You are a research scientist for the National Institutes of Health (NIH) interested in perform- ing a controlled experiment to determine the effects of caffeine on human blood pressure. One group of people will get caffeinated coffee and one will get decaffeinated coffee. Briefly explain why you would want that to be the only variable that differs between the two groups.

12. A is a fake treatment given to patients in the control group.

13. A friend tells you her grandfather’s pancakes are superior to all other pancakes because he puts only hand-churned butter from llamas into the batter. This is an example of what kind of evidence?

Chapter Content: The Properties of Life

Complete the following questions as you read the first chapter content—The Properties of Life:

1. A giant sequoia tree is very different from a human. List two properties these two organisms would exhibit despite all of their obvious differences.

2. A smart phone is not alive. List three characteristics of life that the phone does not exhibit.

3. List the properties of life.

Chapter Content: Major Themes in Biology

Complete the following questions as you read the first chapter content—Major Themes in Biology:

1. The branched structure of human lungs significantly increases the surface area for gas exchange. This greatly increases the efficiency of gas exchange within the lungs. Which of the following unifying themes of biology does this example illustrate?

A) Evolution

B) Relationship to structure and function

C) Interaction within biological systems

D) Information flow

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Chapter 1: Learning about Life

2. Human growth hormone (HGH) is necessary for growth during human adolescence. Pituitary dwarfism is a condition that results from the inability of a person to produce HGH. Luckily, the human gene for HGH can be inserted into E. coli bacteria, which are able to make our HGH. The resulting HGH is used by people who are unable to make their own. What prop- erty about hereditary information makes this possible?

3. Energy and chemicals move through ecosystems in different ways. Energy flows an ecosystem, while nutrients are constantly through the ecosystem.

4. What level of biological organization is represented by Figure 1.14 on page 12 of your textbook?

C ol

or iz

ed S

EM 5

,4 00

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Chapter 1: Learning about Life

5. What about Figure 1.13 on page 12 of your textbook?

6. Even though they have several differences, a bacterium and a human cell will both contain DNA. With respect to evolution, what does this fact suggest?

7. True or false: If false, please make it a correct statement. A rancher uses a particular chicken for breeding purposes because, on average, she observed that the chicken laid more eggs than other chickens. The rancher selecting the desirable trait would be considered an example of natural selection.

Major Theme Connection:

1. As a general rule, viruses are not considered to be alive based on several reasons. One such reason is that some viruses use RNA as their genetic material instead of DNA. Which of the five biological themes does this violate? Briefly explain why.

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Chapter 1: Learning about Life

Common Thread Connection:

1. A scientist at the University of Iowa uses a microscope to observe cells in the brain known as microglia. He makes observations about their structure, location, and activity. The scientist eventually observes the cells undergo a sudden and radical shift in their structure/shape and their motility (ability to move). He asks himself questions about what is causing this shift in behaviors and begins to design an experiment to determine the answer. Briefly describe how the scientist practiced both the exploration and testing aspects of scientific inquiry.

SIMO0333_06_ARG_SE_C01_PRF.indd 7 5/14/18 7:23 PM

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Lab Osmosis And Diffusion

November 11, 2023/in Uncategorized /by Daniel Jennings

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Lab 4 Cell Structure, Osmosis, and Diffusion

Introduction: Connecting Your Learning

The basic building block of life is the cell. Each cell contains several structures, some of which are common to both eukaryotic and prokaryotic cells and some that are unique to specific cell types. This lab will discuss cell structures and how materials are moved in and out of the cell. Specifically, the principles of diffusion and osmosis will be demonstrated by performing a scientific investigation that studies the effect of salt concentration on potato cells.

Focusing Your Learning

Background Information

In 1662, Robert Hooke investigated the properties of cork when he discovered cells. He named them after small rooms in a monastery because they reminded him of them. Years later, in 1837, Schleiden and Schwann were attributed with developing the cell theory. While their original theory was modified, the fundamental ideas be- hind the theory held true. Three general postulates are included in the cell theory: 1) All organisms are composed of cells. 2) The cell is the unit of life. 3) All cells arise from pre-existing cells.

Because a cell is the basic building block of living things, it is important to become familiar with its characteristics. Several structures comprise a cell. Many of these structures are visible with the use of a standard compound microscope. Below are pictures of idealized plant and animal cells, illustrating the important structures.

The cell membrane encloses all cells and is responsible for separating the internal en- vironment from the extracellular space (the space between cells). Because other struc- tures within the cell are also surrounded by a membrane, the outer membrane is of- ten called the plasma membrane.

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The cell membrane is semi-permeable, allowing cer- tain molecules to enter into the cell freely, while oth- ers are prohibited from entering the cell. It is com- posed of phospholipids, which have a head consist- ing of a phosphate group and a tail of two fatty acid chains. The phosphate group is attracted to water

(hydrophilic) while the fatty acid chains are repulsed by water (hydrophobic). When in water, the properties of the phospholipids cause them to form two layers: The hy- drophobic tails face the inside of the double layer (away from the water), and the hy- drophilic heads face out (toward the water). Because two layers are formed, the mem- brane is made up of a phospholipid bilayer, as seen in the image.

The cell wall surrounds the cell membrane in plant cells, bacteria, and some fungi. In plant cells, the cell wall is composed of cellulose. In bacteria, the wall is made mostly of polypeptides (protein) or polysaccharides (carbohydrates). The cell wall provides support and protection and is responsible for giving plant cells their shape.

Another important structure found only in eukaryotic cells is the nucleus. This struc- ture contains the genetic information and is the control center of the cell. Protecting the nucleus is a double-membrane called the nuclear envelope, which, like the plasma membrane, is semi-permeable. It is important to note that although prokaryotes lack a nucleus, they still contain genetic information.

Within the nucleus is the nucleolus. This is the site where ribosomes are formed. Ri- bosomes function to assemble proteins. Many cells have multiple nucleoli, which con- tain concentrated areas of DNA and RNA.

Flagella (singular is flagellum) is Latin for whip. Flagella are whip-like projections of- ten found in prokaryotes, eukaryotic single-celled organisms, and some specific cells (like human sperm). These structures extend beyond the cell membrane and cell wall and are used for locomotion (movement). Although flagella are found in both eukary- otes and prokaryotes, the structure of the flagella is different for each cell type.

Cilia (singular is cilium) are structurally similar to eukaryotic flagella but are smaller and more hair-like. Cilia are found in some eukaryotic organisms. Some cilia are used for locomotion, as in the single-celled paramecium. In other organisms, the cilia act as

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a filter. Sometimes, cilia are used not to move the cell itself, but to move objects through a cell (akin to a conveyer belt).

Vacuoles are specialized organelles that are responsible for storing starch, water, and pigments. They also act as a repository for metabolic wastes. Some plant cells contain a large, central vacuole, which occupies almost the entire cell. Central vacuoles are re- sponsible for providing support, which is based on the amount of water or pressure against the cell wall. If too much water is lost in the central vacuole, a plant will lose its support and appear to droop.

Centrioles are found in all animal cells and some plant cells. These structures, which occur in pairs, are responsible for the cytoskeleton. The cytoskeleton is composed of microtubules, microfilaments, and intermediate filaments. It is with these long struc- tures that the cytoskeleton provides support, maintains the cell shape, and anchors the organelles. The cytoskeleton is also used for moving structures or products.

Within eukaryotes is an endomembrane system. In this system, the endoplasmic retic- ulum, which consists of a membrane that forms folds and pockets, connects the nu- clear envelope, the Golgi apparatus (or Golgi complex), and cell membranes. This system is often called the factory of the cell because each of the individual organelles contributes to the production and delivery of proteins, lipids, and other molecules.

The nucleus contains the blueprints for proteins. These plans are then passed to the rough endoplasmic reticulum (RER). This structure is composed of several folds of a membrane and is covered with ribosomes (these bumps are why it is called rough en- doplasmic reticulum). Once the ribosomes receive the plans, the protein is built. Some proteins will move to the Golgi complex. Other proteins will move to the smooth en- doplasmic reticulum (it is called smooth because it lacks ribosomes). These proteins instruct the organelle to build other molecules, such as lipids and carbohydrates. Like some proteins from the RER, some of these molecules will move to the Golgi com- plex.

The Golgi apparatus is the central post office area of the cell. It receives the products of the rough endoplasmic reticulum and smooth endoplasmic reticulum, packages them, and ships them to their intended destination.

Another structure found only in photosynthetic cells is the chloroplast. This special- ized structure belongs to a class of membrane-lined sacs called plastids (like the vac-

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uole). The chloroplast contains pigments and is responsible for creating food through photosynthesis.

Eukaryotic cells contain an organelle called the mitochondria, which is the site of en- ergy production. This structure is often referred to as the powerhouse of the cell. Cel- lular energy is stored in the form of adenosine triphosphate (ATP).

The ability of a cell to absorb water and nutrients is an important aspect of its sur- vival. Diffusion is the movement of solutes (dissolved molecules) in a solution or ma- trix from an area of high concentration to an area of lower concentration. Molecules move down the concentration gradient: from an area of high concentration to an area of low concentration. The greater the concentration differential, the faster the rate of diffusion. The size, shape, and composition of the solute also affect the ability of a substance to diffuse. These factors become increasingly important when considering the diffusion of substances across the cell membrane. Diffusion, being a passive process, is quite efficient across small distances. However, as distances become longer, the efficiency of diffusion decreases.

Osmosis is the movement of water across a selectively permeable membrane from an area of lower concentration (of solute) to an area of higher concentration (of solute). Remember that everything in the universe is constantly moving toward a state of equilibrium. Living cells contain a small amount of salt. For example, human cells contain 0.85% NaCl. If the solution outside the cell has this same concentration, the solution is said to be isotonic. Because there is no net difference in solutes between the inside and outside of the cell, there is no net movement of water. Higher concen- trations of solutes outside of the cell are termed hypertonic, while lower concentra- tions are termed hypotonic.

An important concept that affects how well a cell can absorb and pass material through the membrane is the surface-to-volume ratio. This formula for calculating this ratio is:

Surface area ÷ Volume

Because cells constantly interact with their external environments to obtain nutrients and remove wastes, it is critical that they maintain a proper surface-to-volume ratio.

As objects of the same shape increase in size, the surface-to-volume ratio decreases.

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For example, suppose there are two cubes. Cube 1 is 1 cm x 1 cm x 1 cm, and Cube 2 is 10 cm x 10 cm x 10 cm. To calculate the surface-to-volume ratio, the formula for de- termining the surface area (SA) of a cube (length x width x number of sides) and the formula for the volume (V) of a cube (length x width x height) must be known. Once the formulas for calculating surface area and volume of a cube are known, the surface area to volume ratios can be calculated, as seen below.

CUBE 1 CUBE 2

Surface Area: 1cm x 1cm x 6 sides = 6cm2 10cm x 10cm x 6 sides = 600cm2

Volume: 1cm x 1cm x 1cm = 1cm3 10cm x 10cm x 10cm = 1000cm3

SA/V: 6cm2/1cm3 = 6.0 cm2/cm3 600cm2/1000cm3 = .6cm2/cm3

As shown in the calculations above, the ratio for Cube 2 is significantly smaller than the ratio for Cube 1. The same trend holds true for cells. As a cell gets larger, the SA/V ratio decreases, meaning that it is not as efficient in moving material in and out of the cell. In other words, the size of the cell membrane relative to the contents of the cell decreases as the cell size increases.

An illustration of the importance in maintaining a high surface-to-volume ratio can be found in the human digestive system. Cells in the human digestive system contain villi, which are finger-like projections. Because of their shape, they have a large sur- face area for a small volume.

Procedures

1. Cell Structure and Function a. Label the following idealized plant and animal cells.

b. Observing Cell Structures Under a Microscope i. Utilize the Virtual Microscope to view several cell structures. When

using the virtual microscope, complete the following steps in the order provided below. Failure to properly perform the steps in the correct order will result in failure to complete subsequent steps. Click to view

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optional detailed instructions. ii. Drag and drop the desired slide onto the microscope.

iii. Click on the stage clip knob on the left of the microscope stage. iv. Adjust the interpupillary distance. First click on the title interpupillary

distance. Next, place the pointer on the images and adjust them until the two images are observed as one image.

v. Adjust the slide position. Place the pointer on the positioner and ad- just the slide so there is a clear view of the specimen.

vi. Adjust the iris diaphragm until a comfortable light is obtained. vii. Adjust the diopter until a clear image is obtained. Use the line on the

slide and move it up or down. viii. Adjust the coarse focus. Use the line and move it up or down until a

clear image is obtained. ix. Adjust the fine focus. Use the line and move it up or down until a

clear image is obtained. x. Adjust the magnification by clicking on the objective numbers on the

microscope. xi. Using the virtual microscope, view Spirogyra. Identify and draw an

image of the chloroplasts. xii. Using the virtual microscope, view the slide of a paramecium. Identify

and draw an image showing the cilia. xiii. Using the virtual microscope, view the slide of the Euglena. Identify

and draw an image of the flagella. 2. Demonstration of Osmosis in a Potato

a. Learn to use the caliper. 1. Take the Vernier caliper out of the lab kit. Examine the scale on the

tool and try to measure the length of an object. Look closely at the scale. The metric scale will be used for measurements in this lab.

2. Read the scale by measuring exactly 2 cm (20 mm). Next, measure 4.5 cm (45 mm).

3. This caliper is accurate enough to measure to the nearest tenth of a millimeter (measured by the small, scored lines in the window). With the caliper in hand, go to this instructional Web site, which describes how to use a Vernier caliper.

Watch the scale move as in an actual measurement.

https://www.riolearn.org/content/bio/BIO156/BIO156_INTER_0000_v8/pdf/Additional%20Instructions%20for%20the%20Virtual%20Microscope.pdf

http://www.physics.smu.edu/~scalise/apparatus/caliper/

http://www.physics.smu.edu/~scalise/apparatus/caliper/tutorial/

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b. Set up the experiment 1. Get four 8 oz. cups from the lab kit. Place a piece of tape on each cup

or glass. Using a pen or marker, label the tape on each cup with one of the following percentages: 0%, 1.75%, 3.5%, and 7%.

2. Using the graduated cylinder, measure out 100 mL of distilled water. Pour the water into the fifth, unlabeled cup.

3. Measure out 1.5 level teaspoons of salt and add it to the unlabeled cup containing 100 mL of distilled water. Mix completely. This is the 7% salt solution.

4. Using the graduated cylinder, measure out 50 mL of this mixture and pour it from the graduated cylinder into the cup labeled 7%.

5. Add distilled water up to the 100 mL mark of the graduated cylinder to make the next dilution. Adding 50 mL distilled water to 50 mL of a 7% solution will result in 100 mL of a 3.5% solution.

6. Using the graduated cylinder, measure out 50 mL of the 3.5% solution and pour it from the graduated cylinder into the cup labeled 3.5%.

7. Add distilled water up to the 100 mL mark of the solution in the grad- uated cylinder to make the next dilution. Adding 50 mL of distilled water to the 50 mL of the 3.5% solution will result in 100 mL of a 1.75% solution.

8. Using the graduated cylinder, measure out 50 mL of the 1.75% solu- tion and pour it from the graduated cylinder into the cup labeled 1.75%.

9. Empty the remaining 1.75% solution down the drain of the sink and rinse out the graduated cylinder with tap water.

10. Using a sharp steak or kitchen knife, slice eight pieces of potato exact- ly 10 mm x 10 mm x 40 mm (1 cm x 1 cm x 4 cm). It is critically impor- tant that these potato core pieces are cut as precisely as possible; they need to all start out having the same volume. A single- edge razor blade may work better than a knife.

11. Determine the volume of the potato cores. The volume, is calculated by multiplying the width x height x length. Therefore, each core starts out with a volume of 4,000 cubic millimeters or 4 cubic centimeters. Measure the cores with both the mm ruler and the calipers. Measuring with the calipers to the nearest millimeter will be good enough for this lab. Create a data table like the one below to record the beginning and

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ending volumes.

Table 1. Potato core measurements

0% saltsolution 1.75% salt solution

3.5% salt solution

7% salt solution

Beginning average volume (cu mm)

Ending average volume (cu mm)

Percent difference

12. Place two measured cores into each solution overnight, or for at least 8 hours. That time period is not critical to the results; it can be longer.

13. Remove the cores from one of the cups and pat them dry with a paper towel. The solution may now be discarded down the drain of a sink.

14. Using the caliper, measure the height, width, and length of the cores, and then determine the volume of each core. Average the measure- ments for the two cores and record in the data table above. The cores can now be discarded.

15. Repeat Steps 11 – 14 three more times: one time for each cup. 3. Illustration of the Importance of Surface-to-Volume Ratios

a. Calculate the surface-to-volume ratio of the following potato cubes: 1. CUBE 1: Length, width, and height are all 5 mm 2. CUBE 2: Length, width, and height are all 3 mm

b. Effect of cell size on diffusion rate 1. With clean hands, cutting board, and knife, cut the skin off of the pota-

to. 2. Using the knife, cut two cubes of potato with dimensions of 1 cm x 1

cm x 1 cm. 3. Using the knife, cut two cubes of potato with dimensions 1.5 cm x 1.5

cm x 1.5 cm. 4. Using the knife, cut two cubes of potato with dimension of 2 cm x 2

cm x 2 cm. 5. Place distilled water into a cup or glass. Add the vial of food coloring

to the water until a dark color is achieved.

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6. Carefully place the potato cubes in the solution. The cubes must be completely submerged in the water. Let them stand in the solution for 2 to 4 hours.

7. After 2 to 4 hours, remove the cubes. Using the knife, cut each cube in half.

8. Using the ruler, measure how far the solution has diffused into each potato cube.

9. Record the results. A sample data table is included below that may be used to organize and record the results.

10. Complete the following calculations to determine the rate of diffusion and record the results.

Rate of Diffusion (cm/min)= Distance of diffusion ÷ time.

Cube Distance of Diffusion Rate of Diffusion

1 cm cubed

1.5 cm cubed

2 cm cubed

Average Rate of Diff.

Assessing Your Learning

Compose answers to the questions below in Microsoft Word and save the file as a backup copy in the event that a technical problem is encountered while attempting to submit the assignment. Make sure to run a spell check. Copy the answer for the first question from Microsoft Word by simultaneously holding down the Ctrl and A keys to select the text, and then simultaneously holding down the Ctrl and C keys to copy it. Then, click the link on the Lab Preview Page to open up the online submit form for the laboratory. Paste the answer for the first question into the online dialog boxes by inserting the cursor in the dialog box and simultaneously holding down the Ctrl and V keys. The answer should now appear in the box. Repeat for each question. Review all work to make sure that all of the questions have been completely answered and then click on the Submit button at the bottom of the page.

10/1/13 10:29 AMBIO156 – Lab 4

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LAB 4

1. Answer the following questions: a. List four cell structures that are common to both plant and animal cells. (4

points) b. What structures are unique to plant cells? (2 points) c. What structures are unique to animal cells? (2 points)

2. List five structures observed in the cell images and provide the function of each structure. (5 points)

a. Structure 1 and function b. Structure 2 and function c. Structure 3 and function d. Structure 4 and function e. Structure 5 and function

3. William is observing a single-celled organism under a microscope and notices that it has a nucleus and is covered in small, hair-like structures.

a. Provide a probable name for this organism (1 point) b. Explain why William came to this conclusion. (2 points)

4. Where in the cell are the chloroplasts located? (5 points) 5. In the Spirogyra cells observed on the virtual microscope, about how many cir-

cular green chloroplasts were seen in a single cell? (2 points) 6. What were the percent differences between the volumes of the potatoes in the

osmosis experiment for each salt solution? (8 points) a. 0% b. 1.75% c. 3.5% d. 7%

7. What extraneous variables might have affected how the results came out in the osmosis experiment? Describe three. (6 points)

a. b. c.

8. In osmosis, which direction does water move with respect to solute concentra- tion? (2 points)

9. Answer the following questions: a. Explain what would happen to a freshwater unicellular organism if it were

suddenly released into a saltwater environment. Use the terms isotonic,

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hypotonic and hypertonic in the answer. (3 points) b. What would happen if a marine organism were placed in freshwater? (3

points) 10. A student purchases and weighs 5 pounds of carrots from a local grocery store.

She notices that the grocery store constantly sprays its produce with distilled water. After returning home, she weighs the carrots again and discovers that they weigh only 4.2 lbs. They also no longer seem as crisp and taut. Provide a possible explanation for why the carrots weighed more at the store, based on the information learned in this lab. (5 points)

11. People always say that leeches can be removed from the body by pouring salt on them. Based on what the student learned about osmosis, provide an explanation that supports or refutes this information. (5 points)

12. What is the rate of diffusion for the potato cubes from the surface-to-volume ex- periment (procedure 3b)? (6 points)

a. Cube 1 b. Cube 2 c. Cube 3

13. Assume the potato cubes are cells. Which cube would be most efficient at mov- ing materials into and out of the cube? Briefly explain the answer. (4 points)

14. From what was observed in the potato procedure, how do the rate of diffusion and surface-to-volume ratio limit cell size? (5 points)

15. One night, Hans decides to cook a hamburger and spaghetti with meatballs. To test ideas of surface-to-volume ratios, he makes a quarter pound hamburger and a quarter pound meatball and cooks them at the same temperature. Which food item will cook the fastest and why? (5 points)

16. While watching a special on animals, Brianna discovers that hares tend to lose heat through their ears. Based on this and what is known about surface-to-vol- ume ratios, propose an explanation as to why hares that live in hot climates (such as the desert) have large, extended ears. (5 points)

17. (Application) How might the information gained from this lab pertaining to cell structures and diffusion be useful to a student employed in a healthcare related profession? (20 points)

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THEO 104 QUIZ 5

November 11, 2023/in Uncategorized /by Daniel Jennings

Question 1

The very nature of human creation gives humans meaning and purpose.

True

False

2 points

Question 2

One of the most basic questions of origin is, “Where did everything come from?”

True

False

2 points

Question 3

Even though vocations are instituted by God, they are not a relevant platform through which to love others and serve God.

True

False

2 points

Question 4

Some humans beings are inherently good and have never sinned.

True

False

2 points

Question 5

Though we often think about what we want to be when we grow up, we are not nearly as reflective on who we are now.

True

False

2 points

Question 6

What passage of Scripture discusses the creation of man in the image of God?

Genesis 1:26-27

Genesis 2:3-4

Colossians 1:15-16

John 1:1

2 points

Question 7

In the eyes of God, all mankind is created equal.

True

False

2 points

Question 8

Which of the following is(are) aspects of being made in the image of God?

Stewardship

Dominion

Relational Ability

Both A and B

A, B, and C

None of the above

2 points

Question 9

The term “image” is both an abstract and concrete term in that it is used to describe both an idea and an actual product.

True

False

2 points

Question 10

The image of God was lost at the fall.

True

False

2 points

Question 11

Though many people downplay the existence of a soul, the arts, which appeal to areas of life greater than biological impulses, are important parts to every culture.

True

False

2 points

Question 12

Does a close reading of the Bible show that Scripture affirms the soul?

Yes

2 points

Question 13

The human personality is primarily comprised of three aspects-the intellect, the emotion, and the _____________.

Thoughts

Consciousness

Will

Sin nature

2 points

Question 14

It is difficult for Christians to deal with naturalism because it can be proven within the realm of science.

True

False

2 points

Question 15

Which of the following is NOT a reason why humans possess an immaterial aspect?

An immaterial aspect of humanity provides a basis for human causation or human initiation.

An immaterial aspect of humanity provides the basis for human freedom

An immaterial aspect of humanity provides the basis for our unified experience

An immaterial aspect of humanity provides the basis for human consciousness

2 points

Question 16

The first sin recorded in the Bible is found in ______________.

Genesis 1:26

Genesis 3

Genesis 1:1

Daniel 2:1

2 points

Question 17

From birth, mankind has a sin condition that can only be resolved through the grace of God.

True

False

2 points

Question 18

The Bible gives a narrative explaining the beauty and dignity of humanity, but does not address the struggle and ugliness that is all too much a part of the human experience.

True

False

2 points

Question 19

The New Testament clearly points out that the Genesis account is a story with lasting consequences.

True

False

2 points

Question 20

Why do people run from the idea of sin?

They do not like being told they are wrong

They do not like the thought of doing something bad

They do not like the consequences of sin

They do not like a problem they are unable to fix

2 points

Question 21

Some people have claimed that sin is just a Christian teaching to repress an individual’s expression of what they feel is right to do.

True

False

2 points

Question 22

According to Romans 1:13 and 1 Corinthians 6:9, sin is only sin when God’s way is willfully and knowingly disobeyed.

True

False

2 points

Question 23

What was the first temptation of Jesus in the wilderness?

The temptation for personal vindication

The temptation to turn stones into bread

The temptation to seek his own kingdom versus God’s kingdom

2 points

Question 24

Which of the following constitutes sin?

Direct disobedience of God’s Law

Indirect disobedience of God’s Law

Both A and B

2 points

Question 25

God sometimes tempts humans to test if they will obey or disobey his commands.

True

False

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THEO 104 QUIZ 4

November 11, 2023/in Uncategorized /by Daniel Jennings

Question 1

The Holy Spirit is _________.

Omniscient

Omnipotent

Omnipresent

All of the above

None of the above

2 points

Question 2

The Holy Spirit was sent to continue the work of Jesus on earth.

True

False

2 points

Question 3

What passage of Scripture specifically mentioned in the textbook reveals the eternal nature of the Holy Spirit?

Genesis 1

Matthew 4

Psalm 119

None of the above

2 points

Question 4

The __________ Creed signifies the belief in the Father, the Son, and the Holy Spirit.

Apostle’s

Nicene

Athanasian

None of the above

2 points

Question 5

The Holy Spirit glorifies Christ through working in the lives of believers to help them be more Christlike in all that they do.

True

False

2 points

Question 6

The Holy Spirit is responsible for which of the following?

Baptism

Indwelling

Sealing

All of the above

2 points

Question 7

Regeneration is only found in the New Testament as a work of the Holy Spirit.

True

False

2 points

Question 8

__________ is the idea of new birth or new creation.

Regeneration

Baptism

Indwelling

Sealing

2 points

Question 9

The Great Commission is recorded 10 times in the Bible.

True

False

2 points

Question 10

The _______ of the believer by the Holy Spirit as part of the family of God refers to God’s completion of the work of salvation.

Baptism

Indwelling

Sealing

None of the above

2 points

Question 11

The filling of the Holy Spirit is in large part dependent on what?

Obedience

Sacrifice

Prayer

Bible reading

2 points

Question 12

The Holy Spirit’s ministry of indwelling and filling consistently evidences itself throughout both the Old and New Testaments.

True

False

2 points

Question 13

Sanctification has both a positive and a negative aspect.

True

False

2 points

Question 14

The filling of the Holy Spirit refers to the control the Holy Spirit has over the life of the Christian.

True

False

2 points

Question 15

The Holy Spirit only intercedes on the behalf of some Christians.

True

False

2 points

Question 16

Which of the following is not one of the passages containing the list of spiritual gifts?

Romans 12:3-8

1 Corinthians 12:4-11

Ephesians 4:11

Galatians 5:22-23

2 points

Question 17

Apostles were those specifically appointed by _______ to be a “sent one.”

Christ

Peter

Paul

Early church fathers

2 points

Question 18

Which of the following is a specific characteristic of spiritual gifts?

They are always spoken of within the larger conversation of unity

They are used for serving one another within the context of the global church

Jesus is the source of the spiritual gifts

All of the above

2 points

Question 19

The gift of _____ is the special ability to organize and plan.

Helping

Managing

Leading

Service

2 points

Question 20

In 2 Peter 3:10-11, the apostle Peter explains the need to use one’s gift in a way that is in service to one’s self.

True

False

2 points

Question 21

Every Christian has every spiritual gift; however, not every Christian is to display all of the fruit of the Holy Spirit.

True

False

2 points

Question 22

Which is not one of the fruit of the Spirit?

Love

Humility

Kindness

Peace

2 points

Question 23

Self-control relates to the disposition of an individual and is seen as meekness or humility.

True

False

2 points

Question 24

There are four important differences between the gifts of the Holy Spirit and the fruit of the Holy Spirit.

True

False

2 points

Question 25

________ is goodness put into action.

Patience

Kindness

Gentleness

Love

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Case Study Bio

November 11, 2023/in Uncategorized /by Daniel Jennings

Case Study 1: The Role of Insulin Resistance in Type-2 Diabetes

Adapted from Case studies by Univ. of Buffalo NY, Nature magazine, Medicinenet, Joselin Diabetes Research Center

Part I Tania is an Undergraduate student from Germany and is visiting Dr. Wen ’s lab under the International Visiting Scholars program. She will be working with Dr. Wen for the summer trying to get some practical research experience which will help her decide between applying to graduate school or medical school . Dr. Wen works primarily on Type-2 diabetes and Tania is interested in his work on trying to understand the role of insulin and cellular signaling in diabetes. She first got interested in this topic because her Uncle has Type – 2 diabetes. She has a list of questions which she hopes she will be able to answer by the end of her project with Dr. Wen. Here is her list and some information to help her understand how cell signaling works

Q1) Cellular signaling is very important in a cell, but what does it have to do with diabetes? Hint: Cellular signaling controls our response to the environment, like changes in the temperature or responses to eating. It helps our bodies maintain homeostasis. Many medications alter cellular signaling in order to treat diseases like cancer, allergies, and diabetes.

Q2) How can understanding cellular signaling help us understand how diabetes occurs and how to treat it? Hint: In cellular signaling each pathway involves many proteins, thus carrying out messages can be very complicated for cells. Understanding cellular signaling in general will help to understand what role it plays in diabetes. Refer to slides from Lecture 4 and revise the details of signal transduction pathways Knowledge Clip 1: What is Cell signaling? A s ignaling pathway has four essential components: (1) the initial signal, (2) the receptor that binds the s ignal, (3) the signaling molecule or molecules that transmit the message, and (4) the effector or effectors that result in a short-term or long-term cellular change. The initial s ignal can range in size and composition from a small molecule l ike nitric oxide (NO), a hormone like estrogen, or a protein like insulin (Figure A). The type of s ignal determines if the receptor s ignal-binding domain can be intracellular or extracellular. For example, estrogen

is hydrophobic and can readily pass through the plasma membrane, so its receptor is intracellular. Other signaling molecules like the protein insulin are hydrophilic and too large to pass through the plasma membrane so the insulin receptor i s an integral membrane protein with

an extracellular signal-binding domain (made of an outer-membrane component alpha and an inner membrane component beta). Once the s ignal (which i s insulin in this case) binds to the receptor, the receptor changes i ts shape or conformation. This conformation change might include the opening of an ion channel allowing ions to travel into the cell (like the Na+/K+ channel) , or i t might include changing the

organization of domains like the extracellular domain of a receptor tyros ine kinase (Fig B). A receptor conformation change causes the associated s ignaling molecule(s) to transition from inactive to active. The s ignaling molecule(s) can carry the message through many di fferent mechanisms. The activated signaling molecule then influences the effector(s) that ca use the short-term or long-term cellular change. A short-term change can be stimulating cellular movement or changing the activation s tate of an enzyme going from inactive to active or active to inactive. This happens for instance when activating an enzyme to increase sugar metabolism. Long-term cellular changes

are generally the result of changes in DNA transcription. For example, a protein could be made to begin cellular replication by activating the cel l cycle.

The s i tes phosphorylated by the previous kinase activate the next kinase, but

another site of phosphorylation on the same kinase could turn it off. The activity of each kinase in the cascade can be regulated in this manner. One common mode of regulation is called feed-back inhibition (Figure 2B). This occurs when

some downstream effector (or result of the cellular response) inhibits an earlier s tep in s ignal transduction. Thus, the dynamics of speed and magnitude of

response can be fine tuned or s topped entirely. This negative regulation is revers ible. In the example in Figure 2B, another enzyme ca lled a phosphatase could remove the phosphate group from the kinase, allowing it to be activated

again. Another common mechanism for multi-protein signal transduction is the activation of a second messenger (Figure 3). A second messenger is generally a small molecule that can travel freely through the cytoplasm or the membrane. Some examples of second messengers are cycl ic-AMP, Ca2+ ions, phosphoinositides (PIP3, PIP2, etc.), and diacylglycerol (DAG). These second messengers are either released from intracellular s tores (l ike Ca2+ ions) or created through enzymatic action (l ike cycl ic-AMP). Once released, second messengers can interact with many targets throughout the cell s imultaneous ly. Thus , second messengers lead to s ignal amplification and increased speed in

s ignal transduction.

After reading this information, Tania has a fair idea of how signaling works. But she has some more questions: Q3) Does the kinase cascade and second messenger signaling where lots of proteins are activated require a lot of energy to make all those extra proteins? Why couldn’t the signal be transmitted with just one signaling molecule? Hint: The above figures show that in the kinase cascade, with each additional kinase activated, more of the next kinase is activated thus growing exponentially. This is called as Signal amplification. Signal amplification can lead to greater cellular changes, and it also speeds up the cellular response. It works the same with second messenger pathways too, with the small molecules activating lots of signaling proteins. Each new signaling molecule also provides another opportunity for the body to regulate the signaling. Answer Questions for Part I in the Case Study I Question sheet Part II Now that Tania understands the basics of signaling and its mechanisms, she is ready to understand why Dr. Wen’s lab studies cellular signaling. Tania’s Uncle’s life is adversely affected by Diabetes. He has to be careful what he eats and he goes for walks most days. He also has to monitor his blood glucose level at regular times and he gives

Signal transduction cascade Signal transduction amplification

himself injections before most meals to keep his glucose levels balanced; it can’t be too high or too low. For instance, after people eat their blood glucose generally goes up. This causes the pancreas to release a signal known as insulin into the blood stream. In diabetics, the cellular signaling is messed up so it doesn’t work as well. So her uncle injects himself with insulin or an insulin analogue. Insulin is a protein that controls cellular signaling of various types. By controlling insulin changing signaling, the adverse effects of diabetes can be managed. Q1) What are the symptoms of Diabetes? Knowledge Clip 2: Symptoms of Diabetes: Hunger and fatigue: Your body converts the food you eat into glucose that your cells use for energy. But your cells need insulin to bring the glucose in. If your body doesn’t make enough or any insulin, or if your cells resist the insulin your body makes, the glucose can’t get into them and you have no energy. This can make you more hungry and ti red than usual .

Peeing more often and being thirstier: The average person usually has to pee between four and seven times in 24 hours, but people with

diabetes may go a lot more. Why? Normally your body reabsorbs glucose as i t passes through your kidneys. But when diabetes pushes your blood sugar up, your body may not be able to bring it a ll back in. It will try to get rid of the extra by making more urine, and that takes fluids. You’ll have to go more

often. You might pee out more, too. Because you’re peeing so much, you can get very thi rsty. When you drink more, you’ll a lso pee more. Dry mouth and itchy skin. Because your body is using fluids to make pee, there’s less moisture for other things. You could get dehydrated, and your mouth may feel dry. Dry skin can make you i tchy.

Blurred vision. Changing fluid levels in your body could make the lenses in your eyes swell up. They change shape and lose their ability to focus .

Yeast infections: Both men and women with diabetes can get these. Yeast is a fungus that feeds on glucose, so having plenty around makes

i t thrive. Infections can grow in any warm, moist fold of skin, including:

 Between fingers and toes

 Under breasts

 In or around sex organs

Slow-healing sores or cuts: Over time, high blood sugar can affect your blood flow and cause nerve damage that makes it hard for your body to heal wounds . Pain or numbness in your feet or legs: This i s another result of nerve damage.

From information given by Dr. Wen, Tania now understands that the symptoms of Diabetes occur due to the presence of high glucose concentrations in the blood and very little of the glucose from the blood getting into the cell. Since glucose is an energy source and it needs to get into the cell to be used, the cells need to use something else for energy. In the absence of glucose, or in the case of diabetes, due to the inability to uptake glucose, proteins or fats are used as energy sources. When the cells start using proteins, it leads to a buildup of ketoacids. Being acids, they lower pH of the blood. This lower pH can damage a lot of tissues, causing the symptoms listed above. Another problem with diabetics is that they lose feeling in their feet, so if they get a blister on their foot they may not feel it. Then it may get infected because diabetics have poor wound healing, and if the infection isn’t noticed it may lead to amputation of the foot or leg Now that Tania understands what the symptom of Diabetes are and what causes them, she is still unclear about how cell signaling is involved in this whole scenario? Q2) What are the steps involved in the insulin signaling pathway? Dr. Wen gives her this video to understand the concepts of insulin signaling. https://www.youtube.com/watch?v=FkkK5lTmBYQ

http://www.webmd.com/diabetes/guide/blood-glucose

https://www.youtube.com/watch?v=FkkK5lTmBYQ

After watching the video, it is pretty clear to her how insulin signaling happens in the cell and how glucose enters the cell. But Tania realizes that Insulin not only affects Glucose uptake by the cell, but also plays an important part in Fatty acid production, protein synthesis and Glycogen synthesis by joining of multiple glucose molecules for storage. So how does it do that? Dr. Wen draws out this simple map to explain some of the other pathways that insulin affects. He explains that the insulin signaling that causes uptake of glucose via the GLUT-4 molecule is a short term change caused by insulin signaling. The other signaling cascades can cause long term effects like: 1) Gene expression and cell division via the MAPK pathway 2) Protein synthesis and cell growth by the AKT-mTORC pathway 3) Glycogen synthesis by the AKT-GSK3 pathway 4) Fatty acid synthesis by AKT-FOXO pathway

Dr. Wen goes on to explain that insulin does not cause the same long-term and short-term effects in different kinds of tissues in your body, like they are different in your muscle and liver. Although, insulin is released into the blood stream so it could bind to receptors on all the different tissues, Insulin binding to the insulin receptor doesn’t have the same effect in the different cell types in our body. Insulin is released into the blood stream, but the amount of a receptor or any downstream signaling effector could affect the short-term and long-term effect. Different cells have the same set of DNA, but the accessibility of that DNA is changed in different cell types. The insulin receptor DNA might not be expressed as much in different tissues because of the DNA packing or a variety of other reasons. Answer Questions for Part II in the Case Study I Question sheet Part III The primary cause of Type-2 diabetes is insulin resistance. This means that even through insulin is present in the blood stream, the cells don’t respond as robustly. Type-2 diabetes occurs as a result of continuous insulin signaling due to genetics, poor diet, obesity, and lack of exercise. This continuous over stimulation of insulin signalin g alters how the insulin receptor and its down-stream signaling pathways will respond to insulin. There have been lots of possible changes to insulin signaling proposed as the key mechanisms responsible for insulin resistance, but the reality is that insulin resistance isn’t understood. Here are a few examples and already known pathways of insulin resistance

Knowledge Clip 3: Causes and types of insulin resistance: Insulin resistance results from inherited and acquired influences. Hereditary causes include mutations of insulin receptor, g lucose

transporter, and s ignaling proteins, a lthough the common forms are largely unidentified. Acquired causes include physical inactivity, diet, medications , hyperglycemia (glucose toxici ty), increased free fatty acids , and the aging process

Classification of prereceptor, receptor, and postreceptor causes:

The underlying causes of insulin-resistant states may a lso be categorized according to whether their primary effect is before, at, or after the insul in receptor (see below). Prereceptor causes of insulin resistance include the following:

 Abnormal insul in (mutations)

 Anti -insul in antibodies

Receptor causes include the following:

 Decreased number of receptors (mainly, fa i lure to activate tyros ine kinase)

 Reduced binding of insul in

 Insul in receptor mutations

 Insul in receptor–blocking antibodies

Postreceptor causes include the following:

 Defective s ignal transduction

 Mutations of GLUT4 (In theory, these mutations could cause insulin resistance, but polymorphisms in the GLUT4 gene are rare.)

Combinations of causes are common. For example, obesity, the most common cause of insulin resistance, i s associated mainly wi th postreceptor abnormal i ty but i s a lso associated with a decreased number of insul in receptors .

Specific causes of insulin resistance

Speci fic conditions and agents that may cause insul in res is tance include the fol lowing:

 Aging: This may cause insul in res is tance through a decreased production of GLUT -4.

 Increased production of insulin inhibitiors: A number of disorders are associated with this effect, such as Cushing syndrome, acromegaly, and stress states, such as trauma, surgery, diabetes ketoacidosis, severe infection, uremia, and l iver ci rrhos is .

 Medications: Agents associated with insulin res istance syndrome include glucocorticoids (Cushing syndrome), cyclosporine, niacin, and protease inhibitors. Glucocorticoid therapy i s a common cause of glucose intolerance; impairment of glucose tolerance may occur even at low doses when adminis tered long term .

 Sodium: High sodium intake has been associated with increased glucocorticoid production and insul in res is tance.

 Anti-HIV therapy

 Insulin therapy: Antibodies are proteins produced by our immune system to neutralize or destroy foreign substances in our body, Antibodies against insulin have been found in most patients who receive insulin. Rarely, the antibodies result in significant prereceptor insulin resistance. Patients with a history of interrupted exposure to beef insulin treatment are part icularly prone to this resistance. Clinically significant resistance usually occurs in patients with preexisting, significant tissue insensitivity to insulin.

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Biology 1334 Lab Assignment #2

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THEO 104 QUIZ 5

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THEO 104 QUIZ 4

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Case Study Bio

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Do you need a similar assignment done for you from scratch? Order now!
Use Discount Code "Newclient" for a 15% Discount!

Do you need a similar assignment done for you from scratch? Order now!
Use Discount Code "Newclient" for a 15% Discount!

Do you need a similar assignment done for you from scratch? Order now!
Use Discount Code "Newclient" for a 15% Discount!

Do you need a similar assignment done for you from scratch? Order now!
Use Discount Code "Newclient" for a 15% Discount!

Do you need a similar assignment done for you from scratch? Order now!
Use Discount Code "Newclient" for a 15% Discount!

Do you need a similar assignment done for you from scratch? Order now!
Use Discount Code "Newclient" for a 15% Discount!

Do you need a similar assignment done for you from scratch? Order now!
Use Discount Code "Newclient" for a 15% Discount!

Do you need a similar assignment done for you from scratch? Order now!
Use Discount Code "Newclient" for a 15% Discount!

Do you need a similar assignment done for you from scratch? Order now!
Use Discount Code "Newclient" for a 15% Discount!