Download Name: Date: Period:______ GL Investigation: Protein Digestion

Name: _______________________________________
Date: ______________ Period:____________ GL
Investigation: Protein Digestion
Student Objectives:
1. Students will be able to describe the difference between mechanical and chemical digestion
2. Students will be able to describe the function and parts of the digestive system.
Introduction__________________________________________________________________
What is a protein?
A protein is a large organic compound constructed of smaller organic compounds called
amino acids. Proteins are used by plants and animals to perform many different functions.
Collagen is an example of a protein, which keeps are skin tight and flexible. As we age, sun
damages this protein and results in wrinkling of our skin. Other examples of a protein include
Antibodies, which are a part of our immune system and defend our bodies from infections.
Why must we eat protein?
Our body must generate millions of proteins each day to maintain our bodily functions. In fact,
about 40% of our body is protein. To construct these proteins, we must digest or break down
other proteins to collect the parts needed to build new proteins. More simply, our body recycles
proteins, using the left-over parts to construct new proteins. Not eating enough protein can
result in stunted growth, loss of muscle mass, and a severely weakened immune system.
How do our bodies break down or digest protein?
What is the first thing you do when you place food in your mouth? You chew. Your mouth is
where digestion or the breakdown of food begins. Your teeth tear and shred the food into
smaller pieces that can more easily go down your esophagus, the tube that carries food from
your mouth to your stomach. This form of digestion is known as mechanical digestion,
because it changes the food physically and not chemically. Chemical digestion also begins in
the mouth but occurs mostly in the stomach and the small and large intestines. Inside the
stomach and intestines are small biological machines called enzymes that chemically break
down food into small nutrients. Acid in the stomach also helps break down food. The nutrients
are carried by the blood and shared with the entire body. Anything that is not absorbed by the
blood becomes waste as removed from the body.
_____________________________________________________________________________
Name: _______________________________________
Date: ______________ Period:____________ GL
Pre-investigation Questions____________________
1. Where in the body does mechanical digestion
occur?
a. Stomach
b. Mouth
c. Small Intestine
d. Large Intestine
2. Where in the body does chemical digestion
occur?
a. Stomach
b. Large and Small Intestine
c. Mouth
d. A and B are both Correct
3. Burning is to paper as ________________ is to
food.
a. Chemical digestion
b. Mechanical digestion
4. Tearing is to paper as ________________ is to food.
a. Chemical digestion
b. Mechanical digestion
5. Which answer below correctly orders the movement of food through the digestive system
a. Mouth, esophagus, stomach, small intestine, large intestine
b. Mouth, esophagus, small intestine, large intestine, stomach
c. Esophagus, mouth, stomach, small intestine, large intestine
6. Using your own words, describe the function of the digestion system.
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Name: _______________________________________
Date: ______________ Period:____________ GL
Instructions_____________________________________________________________
1. Label your three test-tubes as shown below
a. Period# - Group# - A, B, or C (Example: 2-3-A)
2. Add the following material to test-tubes:
a. Tube A: 10 drops of Water
b. Tube B: 10 Drops of 1% HCl (Hydrochloric Acid)
c. Tube C: 10 Drops of 1% HCl + small scoop of the enzyme pepsin
Think to yourself, why are we adding these different substances?
3. Using your hands, mash the small piece of meat in the plastic bag.
Think to yourself, what type of digestion is this similar to?
4. Divide the meat into 3 equal parts and place 1 piece into each test-tube.
5. Draw and label your observations in the box below.
Test-Tube A
Day
1
(Today)
Day
2
(Tomorrow)
Test-Tube B
Test-Tube C
Name: _______________________________________
Date: ______________ Period:____________ GL
Conclusion Questions__________________________________________________________
1. How do your observations for test-tubes A, B, and C, differ from day 1 and day 2?
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2. Which combination of substances was best for breaking down or digesting the meat?
A. Water Only
B. Acid Only
C. Acid and Enzyme
What evidence did you use to answer question # 2?
I observed_______________________________________________________________
________________________________________________________________________
3. Smashing the meat inside the plastic bag was most similar to
a. Mechanical Digestion b. Chemical Digestion
4. The meat being broken down in the test-tube is an example of
a. Mechanical Digestion
b. Chemical Digestion
List one observation that makes you believe the meat chemically changed in the tube.
1. I observed _________________________________________________________
__________________________________________________________________
5. Provide one reasons why the test-tube is a good model of our stomach and 2 reasons
why it’s a poor model?
Advantage:
1. _____________________________________________________________________
_____________________________________________________________________
Disadvantage:
1. _____________________________________________________________________
_____________________________________________________________________