Chem. 454

EXAM 1

55 PTS.

NAME .

1. Health problems seen in young diabetics are often identical to those of elderly non-diabetics. Give one such common health problem and give a reasonable biochemical explanation for this strange parallel. (6)

















2. We all know that glycogen phosphorylase b is converted to a more active phosphorylase a by kinase catalyzed phosphorylation. However, many other effectors can also directly influence this enzyme's activity. For each of the effectors below explain briefly the metabolic logic behind these observed effects.

a. AMP stimulates Phosphorylase a or b activity:








b. ATP inhibits Phosphorylase a activity








c. Glucose directly inhibits liver Phosphorylase a activity








3. Why is glucose-6-phosphatase only found in the liver and not in the muscle? (5)









4. Studying insulin action has always been difficult for biochemists because it causes both phosphorylation and dephosphorylation of various proteins. Using the example of glycogen synthase activity, diagram how insulin causes both phosphorylations and dephosphorylations leading to glycogen synthase activation. Don't for get to label enzymes and receptors, etc.(9)

5. How many ATP's (maximal) could be obtained from b -oxidation of arachidic acid ( a 22:0 fatty acid) under: (show or explain reasoning)

a. aerobic conditions with a functional TCA?














b. carbohydrate starvation conditions (TCA is non functional)? (assume no AcCoA inhibition of b -oxidation) (6)















6. What citric acid cycle intermediate can aspartic acid be converted to by transamination? This intermediate cannot undergo net oxidation to CO2 by the citric acid cycle alone. Trace a metabolic route of known enzymes and intermediates(just names, structures not needed) by which this intermediate may be completely oxidized. (6)












7. Draw the structure of the products of transamination for the following. (8)

a. ornithine (Draw both possibilities)






and .







b. phenylalanine .

c. pyruvate .

d. asparagine .

8. Collagen consists largely of proline and glycine. Would this protein be a good choice for a liquid protein diet? Briefly, why or why not? (3)









9. The "Miracle Thigh Cream" contains a caffeine -like substance (theophylline) in an oily cream. Explain why this might actually work to reduce the circumference of one's thighs. Would you expect is to help you lose weight ? Why or why not? What features of this treatment would cause you to be skeptical about the claims made?(6)





































BONUS:(2pts) Who discovered the 3 dimensional structure of vitamin B12? ß