Legible Please!

C485 Exam IV Fall ‘12

Name______

Legible please!

Do not use acronyms. Use structures whenever they are asked for, or appropriate. Your explanations should be brief. Overly lengthy answers with irrelevant or erroneous material will receive deductions. GOOD LUCK

1. (12 Pts) Draw the structure of isopentenyl pyrophosphate and outline its biosynthesis from AcCoA. You must use structure.

2. (15pts) There are three basic biosynthetic strategies for the synthesis of phospholipids. Starting with phosphatidic acid outline these pathways. Please account for the energetic requirement of synthesizing the phosphodiester bond. You must use structures and provide a specific example for each pathway.

3. (12 pts) Show the reaction catalyzed by aromatase. Draw a mechanism for creation of the reactive iron species that carries out the first reaction. Draw the likely intermediates in the reaction, and the mechanism by which the molecule is aromatized in the final step.

4..(15 pts) List the three most important metabolic junctions. Diagram the like fate of these molecules.

5. (10 pts) Describe the differences between agonists and antagonists. When would you want a drug to act as an agonist? An antagonist? Is tamoxifen an agonist, or an antagonist?

6. (16 pts) Draw the degradative pathway for the coversion of AMP and GMP to uric acid. A defect in the degradative pathway for adenosine results in a condition known as SCIDS. What is this defect? When this step operates normally, what is the thermodynamic driving force?

7. (16 pts) Starting with palmitoylCoA, draw the biosynthesis of ceramide. You must use structures and show the mechanism of the first step of this pathway.

8. (12 Pts) Starting with cholesterol, outline the biosynthesis of the major sex hormones (estrogen and testosterone). You must use structures. What are the actual sex hormones that are most active in stimulating a receptor response? Explain how receptors might differentiate between two molecules that are so similar.

9. (8pts) Explain the regulatory strategy used to control purine biosynthesis. Make sure you specifically state which reaction is affected, and what is causing the effect. Explain the rationale for this type of effect.

Point breakdown

Possible actual

1) 12 ______

2) 15 ______

3) 12 ______

4) 15 ______

5) 10 ______

6) 16 ______

7) 16 ______

8) 12 ______

9) 8 ______

TOTAL 116 ______