Chapter 12:

Question 1

Which of the following is required for fatty acid synthesis? Select all applicable answers:

a. Glyceraldehyde-3-phosphate.
b. NADPH.
c. ATP Synthase.
d. Acetyl CoA.
b. Malonyl CoA

Answer 1

b - NADPH.
d - Acetyl CoA.
e. - Malonyl CoA.

Question 2

Explain the steps of fatty acid synthesis:

Answer 2

1. Acetyl coA (Item 1) contributes an acetate unit to an acyl carrier protein domain with 4’-phosphopanetheine.
2. Malonyl coA (Item 2) adds a 3 carbon malonate unit onto the acetate unit. Malonyl coA will loose CO2 in the process, and carbons will be added by units of 2. Until the fatty acid is formed.
3. NADPH (item 3) reduces the product and water is lost - forming a finished fatty acid.

Question 2

Since ATP is the primary source of energy for the cell, which of the following must be true?

1. An ATP molecule is at an energetic equilibrium.
2. Using ATP in a chemical reaction is endergonic to the ATP.
3. The gibbs free energy of ATP is negative.
4. ATP requires several enzymes in order to release energy.

Answer 2

The gibbs free energy of ATP is negative - so the reaction of releasing energy would be spontaneous and exergonic (releases energy)

Question 3

Which of the following would best describe the structure of DNA:

1. DNA is made up of a sugar group, a phosphate group, and several deoxynucleoside triphosphates.
2. The phosphate group on DNA carries a strong negative charge, giving a molecule of DNA an overall negative charge.
3. The backbone of DNA is held together through hydrogen bonds between the deoxyribose and phosphate groups.
4. DNA is comprised of a sugar with a hydroxyl group on the 2’ carbon.

Answer 3

2. The phosphate group on DNA carries a strong negative charge, giving a molecule of DNA an overall negative charge.

Question 4

Deoxynucleoside triphosphates in DNA:

Answer 4

Adenine-DNTp, Guanine-DNTp, Cytosine-DNTp, and Thymine DNTp.

Question 5

Purines:

Answer 5

Adenine and guanine.

Question 6

Pyrimidines:

Answer 6

Cytosine and thymine (or uracil)

Question 7

Why does Adenosine triphosphate have a very negative Gibbs free energy?

Answer 7

Because it will occur spontaneously because the hydrolysis of its phosphate groups is highly exergonic - this provides energy needed to add adenine to a growing strand of DNA

Question 8

If the Gibbs free energy of ATP was positive, how would this impact the cell?

a. The cells will continue with normal cellular processes.
b. The hydrolysis of ATP will require energy, and cause a lot of cellular processes to halt.
c. There will be an increase in the hydrolysis of ATP, creating an excess in the cytosol.
d. The cell will reach equilibrium and no longer require ATP to function.

Answer 8

b. The hydrolysis of ATP will require energy, and cause a lot of cellular processes to halt.