Name____________________

1. (15 points) Elephant seals are sea mammals that obtain all of their water via metabolism. Their diets consist mainly of squid, and delicious morsels have a very high fat content. In addition to using stored fat for insulation, they also use fat stores as a source of water.

a. (5 points) What are the specific reactions that produce water?

b. (5 points) How many moles of water are generated per mole of palmitate? (Your reasoning is the important part of this answer. Please demonstrate how you determined this number.)

c. (5 points) How many liters of water can be obtained from β-oxidation of 5 lbs of palmitic acid? (The density of water is 1 g/mL.)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

2. (15 points) Compare the net yield of ATP from the complete oxidation of hexanoic acid versus the complete oxidation of glucose. List all of the reactions that generate ATP. If you consider that each mole of ATP requires 51.8 KJ for its synthesis, do the values for the amount of ATP energy account for the caloric content of fat (hexanoic acid= 9kcal/gram) and (sugar glucose=4 Kcal/gram)? Why or why not.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

3. (15 points) Complete the following table for the β-oxidation enzymes. Use hexanoyl CoA as a starting material.

 

Enzyme

 

Cofactor (s)

 

Structure of the product(s)

 

 

FAD

 

 

 

 

 

 

Hydratase

 

 

 

 

 

 

 

 

 

 

 

 

 

 

NAD

 

 

 

 

 

Thiolase

 

 

 

 

 

 

 

 

 

 

 
 

Part II. Please answer each question using complete sentences in well organized paragraphs.

 

4. (10 points) Human brains require glucose or ketone bodies as their sources of energy. During times of fasting, the liver supplies the brain (via the blood) with glucose that it makes from oxaloacetate. If a person only has acetyl CoA (a product of fatty acid metabolism) and the Kreb=s cycle enzymes and the enzymes to make glucose from oxaloacetate, can this person=s liver supply the brain with glucose? Why or why not? Be specific.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

5. (10 points) If a patient had a defect in pyruvate metabolism, what metabolites would build up? Based on what you know about the enzymes that metabolize pyruvate, describe possible treatments and the rationale for using each treatment.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

6. (10 points) Fats are not soluble in blood, thus they must be transported through the blood on various carriers. Dietary fat, mobilized fat from adipocytes and excess dietary fat are all transported on different carriers. Describe each type of carrier and the destination of each type of fat.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

7. (10 points) Why is oxygen essential for the operation of the Kreb=s cycle? Answer this in terms of how all of the reactions in the Kreb=s cycle are regulated and how oxygen in involved in the overall process of metabolism. Be specific.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

8. (15 points) Ammonia is especially toxic to neurons, hence excess ammonia must be eliminated from all living organisms. Fully describe how excess ammonia is removed from ureotelic organisms. Include all relevant reactions starting with excess amino acids in the tissues and ending with the molecule that is excreted. How is this process controlled?