CHEM 4722/5722 Homework Set #3 (due beginning of class Thu Apr2)

Homework is to be turned in prior to class and should be done onplain white printer paper. If not, it will be returned forresubmission with a penalty assessed. Word processing should beused for any narrative answers. Calculations and mechanisms can bedone freehand but must be very neat, organized, legible and onplain white paper. No lined paper will be accepted.

1. An example of a unsaturated fatty acid is cis-11-heptadecenoicacid. If this compound is oxidized down to CO2 and water viaβ-oxidation and subsequent pathways, how many ATP equivalents canbe obtained? Show all work and list where all of the ATPs comefrom.

2. Draw out both steps of the malic enzyme mechanism for theconversion of malate to pyruvate. Include nicotinamide moieties,acid/base catalysis, and electron movement.

3. Write a balanced stoichiometric equation for the synthesis ofsqualene from acetyl-CoA. Indicate the reactions you used todetermine your answer and show all work.

4. Refer to your lecture notes or your book for the synthesis ofsphingomyelin. Write out the mechanisms (reactant, productstructures and electron movement) for each synthetic step to thefinal product.

5. Mice were divided into four groups, two of which were fed anormal diet and two of which were fed a cholesterol-rich diet.HMG-CoA reductase mRNA and protein levels from liver weremeasured.

   1. a) What is the effect of cholesterol feeding on HMG-CoAreductase mRNA?

   2. b) What is the effect of cholesterol feeding on HMG-CoAreductase protein?

   3. c) Why is the result in panel B surprising in light of theresult in panel A?

   4. d) Suggest possible explanations for the result in panel B.