Chapter 5 Review

1. Which of the folloing 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 c. amino 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
Short Answer
8. Besides satisfying your hunger, why else might you consume a big bowl of pasta the night before a race?
Because pasta contains fat and starch, which is a good source of energy for storage.
9. How are glucose, sucrose, and starch related?
Starch is made up of glucose monomers. Sucrose consists of glucose and fructose.
10. What are steroids? Describe two functions they have in cells.
A steroid is a lipid molecule in which the carbon skeleton forms four fused rings. Two steroid hormones: Testosterone and estrogen contribute to major differences in the appearance and behavior f male and female mammals.
11. How are polypeptides related to proteins?
Proteins are composed of one or more polypeptide chains.
12. How does denaturation affect the ability of a protein to function?
The polypeptide chains become tangled up with one another. Heating unfolds proteins because most of the forces that maintain folding are weak attractions between pairs of side group, an between side groups and water. Since a protein's function depends on its shape, a protein that becomes denatured and loses its shape also loses its ability to work properly.

14. Analyzing Diagrams
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.
Dehydration reaction. When a monomer is added to another monomer, a water molecule comes out.
c. If an amino acid were added to this chain, at what two places could it attach?

15. Analyzing Graphs
a. At which temperature does enzyme A perform best? Enzyme B?
38 degrees. 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 frm which organism.
Enzyme A came from humans and enzyme B came from thermophilic bacteria.
c. Propose a hypothesis that explains why the rate of the reaction catalyzed by enzyme A slows down at temperatures above 40 degrees.
Because every enzyme have different conditions in which they work the best. Enzyme A may not work well after 40 degrees.