Humboldt State University ® Department of Chemistry

Richard A. Paselk

Chemistry 431

 Chem 431/8

 Exam II


 Fall 1994

 (100 pts)

A Key is available by clicking here

(3) 1. Draw the complete structure for ATP

(20) 2. For each of the pathways listed below fill in the table to describe its regulation in terms of main regulatory enzymes, types of control (e.g. substrate availability, allosteric effectors, product inhibition, etc), and the substance(s) involved as effector, inhibitor etc.

 Pathway  Enzyme(s) or rxn  Type of Control  Substance(s)
 Pentose-Phosphate Shunt      
 Kreb's Cycle (overall)      

(15) 3. Calculate the net energy gain or loss in (ATP equivalents) for the complete oxidation of alpha-ketoglutarate (-O2CCH2CH2COCO2-) to oxaloacetate (-O2CCH2COCO2-). Show your work in a table with one reaction per line as we have done in class [i.e.: glycerol DH x 2; 2 NADH; () ATP etc].

(22) 4. Outline a pathway for the breakdown of glucose to carbon dioxide and water Structures are not required (names or abbreviations are OK), but all cofactors and enzyme types must be identified at the appropriate locations, and the production/use of Pi, NTP, FADH2, and NADH must be noted.

(18) 5 a. Write out a detailed mechanism for Aldolase, starting with F-6-P to give DHAP and GALP.

b. Name the types of catalysis used in your mechanism, and identify (i.e. circle and label) where each occurs.

c. Draw a kinetic mechanism diagram for your mechanism and name it using Cleland nomenclature.

(12) 6. Describe and/or explain thefollowing:

a. lipid bilayer:

b. High energy compound:

c. futile cycle:

d. Energy charge:

(10) 7. Consider the strategies of the reactions in the Kreb's cycle starting with Citrate

(-OOCCH2CH(COO)CH2COO-) and leading to succinate.

a. What kind of chemical transformation first occurs with citrate and why?

b. How is the second oxidation set up?

c. In going from oxaloacetate to citrate to succinyl CoA an acetyl group (2 Cís) is added and two CO2's are lost, with carbon now being in its most oxidized state. Can you now consider that the acetyl group is now completely oxidized? Why or why not? (Hint: why do we need to make oxalacetate now?)


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Last modified 17 August 2007