Chapter 5 Review Questions

pg 106 1~4, 12, 14,15

1) Which of the following is NOT an organic molecule?
c. water

2) Which of the following terms includes all the other terms on this list?
b. carbohydrates

3) Which term is most appropriate to describe a molecule that dissolves easily in water?
c. hydrophilic

4) Cholesterol is an example of what kind of molecule?
b. lipid

5) The 20 amino acids vary only in their
b. side groups

6) A specific reactant an enzyme acts upon is called the
d. substrate

7) An enzyme does which of the following?
b. lowers the activation energy of a reactant

8) Besides satisfying your hunger, why else might you consume a big bowl of pasta the night before a race?
When you need to run for a race, you need extra energy, and extra energy needs extra sugar to be stored in your body. So, the night before the race, it would be reasonable to devoure a big bowl of pasta for the excess sugar you need the next day.

9) How are glucose, sucrose, and starch related?
Glucose, sucrose, and starch are all sugars. Also, glucose is a part of sucrose and also, 4 glucose molecules make up starch.

10) What are steroids? Describe two functions they have in cells.
Steroids is a kind of lipid that acts as a signal trasmitter. It travels around the cell to send messages. Estrogene and testosterone in the body give male and female characteristics to people and also, a well know steroid, cholesterol, is in the membrane that surrounds your cells.

11) How are polypeptides related to proteins?
Long polypeptide chains, made up from many variations of amino acids, make a specific shape of the protein that helps determine it's functions.

12) How does denaturation affect the ability of a protein to function?
When denaturation happens, due to the change in pH or temperature, hot molecules can collide with the uncoiled polypeptides and breaks the protein apart, thus making it loose it's ability to function properly.

14) Analyzing Diagrams. The reaction below shows two amino acids joining together.
a. One product of this reaction is represented by a question mark. What molecule is it?
It is a water molecule
b. What is this kind of reaction called? Explain.
It is called a dehydration reaction because when the two amino acids connect, the water molecule is released.
c. If an amino acid were added to this chain, at what two places could it attach?
The two molecules can attach to the hydrogen molecule on the left, and the OH molecule on the right side.

15) Use the graph to answer the questions below.
a. At which temperature does enzyme A perform best? Enzyme B?
Enzyme A performs best at around 38 degrees while enzyme B performs best at around 78 degrees.
b. Knowing that one of these enzymes is found in humans and the other in thermophilic (heat-loving) bacteria, hypothesize which enzyme came from which organism.
Enzyme A is most likely the enzyme that is in humans because the human has a body temperature close to around 38 degrees (36 to be exact) and the heat loving bacteria probably contain enzyme B.
c. Propose a hypothesis that explains why the rate of the reaction catalyzed by enzyme A slows down at temperatures above 40°C.
After 40 degrees celcius, the reaction could carry on without any more help of catalyst A. That would mean that the temperature was hot enough for the enzymes to continue on with the reaction.