BIOCHEMISTRY 4613/6613

Exam 1 - January 28, 2000

Row number: Name:

Short Answer:

1. Define each of the following energy terms. (3 points each)

a) Enthalpy

b) Entropy

c) Free energy

2. In the reactions, A-->B, B-->C, and C-->D, the standard free energy changes are -3, +8 and -12 kJ, respectively. What would be the standard free energy change for A-->D? (3 points)

3. Your breakfast cereal contains 10% protein, 1% fat and 85% carbohydrate. What would be the estimated metabolizable energy content of 100 g of this cereal based on physiological fuel values? (3 points)

4. Consider the following reactions:

A-->B G = - 2.5 kJ/mol

B-->C G = -16.5 kJ/mol

What would be the overall G for the conversion of A-->C? (3 points)

5. Indicate which of the following states of matter has the highest entropy? (3 points)

solid, liquid or gas

6. Which of the following 2 compounds is considered a high-energy compound? (3 points)

glucose 6 phosphate or phosphoenolpyruvate

Why? (3 points)

7. List 4 important factors which contribute to the product(s) of hydrolysis of a high-energy compound being more stable than the reactant. (12 points)

a)

b)

c)

d)

8. Indicate which of the following compounds is the most oxidized. (3 points)

an alcohol, an aldehyde or an alkane

9. Indicate which of the following vitamins serve as the precursor of NADPH. (3 points)

niacin or riboflavin

10. Indicate which of the following coenzymes has a strong absorbance at 340 mµ. (3 points)

NADH or FADH2

Reactions: Give the name of the substrate(s), product(s) and coenzyme(s) for each of the following enzymes. Also indicate if the reaction is reversible or not. No structures necessary.

11. Hexokinase (8 points)

12. Phosphofructokinase (8 points)

13. Phosphoglycerate kinase (8 points)

14. Pyruvate kinase (8 points)

15. Glucose 6 phosphate dehydrogenase (8 points)

Short Answer:

16. Name the 2 enzymes that are coupled during:

a) anaerobic glycolysis (4 points)

b) alcohol fermentation (4 points)

17. List 2 important functions of the pentose shunt or pentose phosphate pathway. (4 points)

a)

b)