BIO 102 Lab 03: Chemical Digestion and Nutrition
To submit, print this document, complete all lab activities, take a photo of your bile experiment, and answer the review questions. Scan your lab pages using the free phone app AdobeScan, and upload your PDF and your bile photo to Canvas.
· Please turn in only pages with completed work (ie., omit pages such as page 1 that only provide instructions)
· Please write your name on the 1st page you submit
If you have a disability that makes it difficult to complete this lab, please contact your instructor.
Copyright © 2016 by Mary Vander Maten and Jill Caporale.
OBJECTIVES
After completing this lab, you should be able to:
Provide an example of how an enzyme is named.
Explain the functions of enzymes during digestion.
Note the effect of bile salts on fats.
Complete a personal diet assessment
Explain Body Mass Index and its relationship to health.
INTRODUCTION
Enzymes are an important group of proteins that enable cells to carry out the chemical reactions needed to support life at temperatures that the cells can tolerate. Enzymes are organic, or biological, catalysts. They speed up chemical reactions that would otherwise occur at much slower rates and can be used over and over many times. The chemical that the enzyme affects is called the substrate. An enzyme is named by adding “–ase” to the name of the substrate it acts upon. For example, the enzyme that speeds up hydrolysis, or digestion, of fats is called lipase and the enzyme that breaks down cellulose is called cellulase.
Part 1: DIGESTION
•Mouth: The Digestion of Starch
Amylase is a protein that is an enzyme produced by the salivary glands and pancreas. Recall that starch is a complex carbohydrate composed of many glucose molecules bonded together. Amylase begins starch digestion in the mouth and hydrolyzes the starch into less complex carbohydrates, such as maltose, a disaccharide. Starch digestion continues in the small intestines.
Starch ⟶ Simple Sugars
via Amylase
•Stomach: The Digestion of Proteins
Protein digestion is initiated in the stomach by proteases such as pepsin and continues in the small intestine.
Protein ⟶ Amino acids
via Pepsin
Although there is some enzyme activity in the stomach, much of the work is mechanical. Searching online, find diagrams or photos of the human stomach’s interior. (Figure 33.8 in your textbook does a poor job clearly showing the stomach interior). Specifically pay attention to the illustrations of the stomach’s interior surface to observe the rugae lining the inside of the stomach.
•Small Intestine: The Primary Site of Digestion and Absorption
Don’t let the name “small intestine” deceive you. The name describes its relative circumference to the large intestine. In contrast, the length of the small intestine is about six meters whereas the length of the large intestine is about one and a half meters.
Most digestion and absorption takes place in the small intestine. Carbohydrate and protein digestion are completed in the small intestine. Lipid and nucleic acid digestion are initiated and completed. Although digestion occurs in the small intestine, some enzymes necessary for the digestion are produced by the pancreas.
The enzymes produced in the pancreas are transported to the duodenum by the pancreatic duct. Bile, produced in the liver and stored in the gall bladder, is delivered to the small intestine to aid in fat digestion. Bile is an emulsifier but is not an enzyme. It enables a more rapid enzymatic breakdown of lipids by increasing surface area of fats (by creating smaller droplets).
Microscopic Investigation of the small intestines
Look at a slide of columnar cells in the small intestine.
https://www.dartmouth.edu/
1. The brush border at the distal end of the columnar cells form the upper layer of the microvilli.
How do you think microvilli increase absorption?
2. You will notice some of the columnar cells contain small globules of mucus. These cells are called goblet cells. Why do you have cells in your intestines that produce mucus? (Isn’t mucus just for your nose?)
3. How many feet are in 6 meters? How many feet in 1.5 meters? Why are these numbers important in this lab? (For reference, the Chevy Suburban SUV is 5.7 m long)
Effect of Bile on Fats
Materials for at home demonstration:
2 clear drinking glasses
Dry mustard (see *Note below)
Spoon
Timer
Safety goggles recommended for all at-home experimentation/demonstration
Water
Into each glass, place both 3 Tablespoons of vegetable oil and 3 Tablespoons of distilled water (both glasses should have oil and water). You will be using dry mustard to substitute for bile. Add a pinch of dry mustard into glass B2. Stir the mixtures for one minute. Carefully observe both glasses for 3–4 minutes. Record your results in Table -2.
2-2 Effect of bile salts on fat dispersal.
| Tube |
Observation (size of fat droplets) |
| B1 (oil + water) |
|
| B2 (oil + water + dry mustard) |
|
The mustard acts an emulsifier. Dispersing the fat globules of the oil into smaller droplets.
Spices like dry mustard are used in the preparation of salad oil are used not only for taste, but to break the oil into smaller particles, thus keeping the salad dressing as a suspension. Bile, emulsifies fat in the small intestines, dispersing the fat into smaller droplets thereby creating more surface area for lipases to work, which speeds up the digestion of fats.
*Note: If you do not have dry mustard, you can use an eighth of a teaspoon of regular liquid yellow mustard
Part 3: Stomachache
We have all experienced the gastrointestinal discomfort and sometimes pain caused by a bout of diarrhea. Make an educated guess regarding the source of the pain. Observe a diagram of the human digestive system. (Refer to your copy of the textbook Campbell: Biology in Focus 2nd edition it is located on page 693). Although we commonly refer to such pain as a stomachache, where is the likely emanating? Explain your reasoning.
NUTRITION AND HEALTH – How healthy are you?
Obesity increases risk of diabetes, high blood pressure, heart disease, stroke, arthritis, and even some cancers. Chronic conditions such as diabetes and high blood pressure make COVID-19 outcomes worse, resulting in either a longer disease course or in ~3% of all COVID patients, death.
Activity 1: Personal Assessment
There are 2 ways to see if your weight is in a healthy range.
1) One method is to measure your waist circumference. It is best if women have a waist size under 35 inches and men under 40 inches. Find a tape measure and measure your waist. _________
2) The body/mas index (BMI) is another way to see if your weight is in a good range. The National Institutes of Health (NIH) has a quick BMI check here: https://www.nhlbi.nih.gov/health/educational/lose_wt/BMI/bmicalc.htm
Your BMI _____________
Activity 2: You are a health care worker
You are the nurse or physician for these patients. Determine the BMI and circle the correct weight range:
Patient 1 Male, 5’10” 200 pounds
BMI: ________
Underweight/Normal/Overweight/Obese
Patient 2 Female, 5’ 5” 110 pounds
BMI: _________
Underweight/Normal/Overweight/Obese
When can BMI be misleading? It does not allow for variations in muscle mass, gender, or body (ie., skeletal) frame.
Patient 3 Male college football player in top physical shape: 6’ 2” 245 pounds (average weight of NFL player)
BMI: _________
Underweight/Normal/Overweight/Obese
Is the B.M. Index representative in this case? __________________
Activity 3: Fat versus Muscle
Fat characteristics: less dense, less metabolically active
Muscle characteristics: more dense, more metabolically active
Will it be easier to maintain a target weight if your body contains more muscle or more fat in the body?
Why?
Fat tissue (like all tissue) is composed of living cells that require energy to function. Explain how this fact might impact an obese person’s efforts to lose weight?
Activity 4: Calculating Calories needed to survive
The calorie is a measure of the amount of energy contained in a substance. (To observe the chemical energy in a food being transformed into visible heat energy, look for videos online entitled “burning a sugar cube”). Hence, all foods have caloric value, even “junk” foods. To determine the number of calories in a given food, they are actually calories are measured by burning the food in a special container and measuring the heat released. (You may have used a device similar to this in chemistry class, a bomb calorimeter.)
How many calories do you need each day? It depends on your gender, age, and activities.
Here are approximate examples of Calories burned/hour for a 150-pound person:
| Sleeping |
40 Calories per hour |
| Sitting |
80 Calories per hour |
| Standing |
120 Calories per hour |
| Walking |
280 Calories per hour |
| Swimming or dancing |
450 Calories per hour |
| Running |
600 Calories per hour |
1. Calculate daily calories needed for a 150-pound person if s/he sleeps 8 hours, sits 10 hours, stands 3 hours, walks 2 hours, and dances 1 hour in each 24-hour period: _________________________
2. Calculate calories for your own typical day:
3. What are obstacles to encouraging people to engage in more physical activity? What could be done to encourage more exercise in busy daily schedules?
Activity 5: What kind of Calories are best?
A healthy diet can make a big difference in overall fitness. According to the CDC (Centers for Disease Control), “poor nutrition contributes to many costly diseases, including obesity, heart disease, and some cancers.” (www.cdc.gov/nutrition)
Here are some recommended numbers, from U.S. Guidelines (https://health.gov/our-work/food-nutrition/2015-2020-dietary-guidelines/guidelines/appendix-7/ ), for a normal diet of 2200 calories per day:
10-30% protein, or 110 grams (20% of 2200 = 440 calories divided by 4 = 110 grams*)
25-35% fat, or 73 grams (30% of 2200 = 660 calories divided by 9 = 73 grams**)
45-65% carbohydrates, or 275 grams (50% of 2200 = 1100 calories divided by 4 = 275 grams*)
*There are 4 Calories per gram of protein or carbohydrate.
**There are 9 Calories per gram of fat.
You can check calories and grams on food packaging, or by looking online
Food examples
1. We likely consume large quantities of sugar in our diets. For example, a can of Coke contains 42 grams of sugar.
a. Which is true about this amount of sugar as related to the daily requirement for carbohydrates?
It is 5%
It is 15%
It is 25%
b. The American Heart Association recommends no more than about 30 grams of simple sugar a day.
(https://www.heart.org/en/healthy-living/healthy-eating/eat-smart/sugar/added-sugars)
c. Is this simple sugar the best carbohydrate to consume? Why or why not? __________________________________________________________
d. List food sources of complex carbohydrates: _________________________________
_________________________________
_________________________________
_________________________________
2. Many of us may also consume too much fat. For example, a small serving of French fries at a fast food restaurant has about 230 calories and contains 44% fat (11 grams).
Here are some other sources of fats. Which do you eat?
Nuts and seeds Fatty fish Avocado
Cheese Eggs Butter and oils
3. What about salt? The sodium in NaCl can cause problems such as hypertension in some individuals (this will be discussed when studying the circulatory system). Processed foods are typically high in salt.
If you want simple help with your diet, check out MyPlate at https://www.choosemyplate.gov
Review Questions: (to be completed and submitted)
1. Define the term “substrate”:
2. Explain the role of enzymes in chemical digestion:
3. a) Test your knowledge of naming enzymes. What is the enzyme that works on the following substrates?
Substrate: lipids. Enzyme: _______________________
Substrate: peptide. Enzyme: _______________________
Substrate: lactose. Enzyme: _______________________
b) You may have heard of a friend or family member being “lactose intolerant”. This is caused by the individual lacking an enzyme to digest the sugar most commonly found in milk. What is your guess of the name of this enzyme? Doing some independent online research, what happens when a person is incapable of digesting this milk sugar, lactose? Why do you think that evolutionary change has removed the ability of grown adults to digest milk sugars?
4. a) Bile is made in the liver, stored in the gallbladder and is secreted into the small intestines to assist with digestion of fats through its action as an emulsifier. What is an “emulsifier”?
b) What is the difference between and emulsifier and an enzyme?
c) Performing online research, what are everyday examples of emulsified items that you eat/drink?
5. Explain the function of bile:
6. How do you think microvilli work to increase absorption?
7. What cells in your intestines produce mucus?
8. For each of the following substrates, state the locations of its chemical digestion occurs in the body, which type of enzyme is involved, and what units these molecules are broken down into.
| Organic Molecule |
Location of digestion |
Enzyme involved |
Monomer units |
| Carbohydrate |
|
|
|
| Fats (triglyceride) |
|
|
|
| Proteins |
|
|
|
9. The Body Mass Index uses __________ and _____________ to see if a person’s weight is healthy.
10. Fill in the chart below.
| Type of Tissue |
More or less dense |
More or less metabolic activity |
| Fat |
|
|
| Muscle |
|
|
11. Number these activities in order of activity, starting with the highest (you may rank activities as tied for equal activity, denoting them as, for example, “2-tied”):
___ walking ___ sitting ___ running ___ riding a bicycle
___ sleeping ___ swimming ___ standing ___ using a skateboard
Why did you rank a specific activity as highest, and why?
12. Most processed foods have too much (check all that apply)
___ fresh fruit ___ salt ___ fresh vegetables
___ water ___ whole grains ___ fat
___ simple sugar ___ protein ___ leafy vegetables
1
Bio 102 Lab 03: Chemical Digestion and Nutrition
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