Chapter 5 Review (pg 106-107)

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?
a. polysaccharide

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 reaction

8. Besides satisfying your hunger, why else might you consume a big bowl of pasta the night before a race?
It will fill you up with carbohydrates that can be broken down for energy during the race.

9. How are glucose, sucrose, and starch related?

They are all kinds of sugar.

10. What are steroids? Describe two functions they have in cells.

Steroids are special lipids that travel arounnd the body as chemical signals. Estrogen and testosterone work like this and are major components for the male and female appearances. Cholesterol is a steroid found in cell membranes from where other steroids are made.

11. How are polypeptides related to proteins?

Proteins consist of amino acids linked in large chains called polypeptides.

12. How does denaturation affect the ability of a protein to function?

After a protein is unraveled in a process called denaturation, it is no longer able 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. Which molecule is it?
water
b. What is this kind of reaction called? Explain.
This is called a dehydration reaction because two hydrogen molecules and an oxygen molecule were removed so the two amino acids could bond. The left over molecules make up water.
c. If an amino acid were added to this chain, at what two places could it attach?
They could attach either to the H on one side or the OH on the other side.

15. Analyzing Graphs Use the graph to answer the questions below.
a. At which temperature does enzyme A perform best? Enzyme B?
Enzyme A performs best around 38 degrees Celsius. Enzyme B performs best around 78 degrees Celsius.
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 probably found in humans while enzyme B is probably found in thermophilic bacteria.
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 Celsius, it's hot enough for reactions to take place on their own without the help of an enzyme.