Humboldt State University ® Department of Chemistry

Richard A. Paselk

Chemistry 438

 Chem 431/8

 Final Exam


 Fall 1994

 (200 pts)

A Key is available by clicking here

(20) 1. For each of the following reactions show all of the cofactors you would expect and name the enzyme type.





(20) 2. What is the P/O ("P to O ratio") for the complete oxidation of hexanoate {CH3(CH2)4COO-}? Show calculations/reasoning for credit! (Set up a table similar to those we've used for ATP equivalents in glycolysis, etc.)

(20) 3. a. Write a detailed mechanismfor alanine amino transferase (Transaminase).

b. Draw and label a kinetic mechanism diagram for this reaction and name it using Cleland nomenclature.

(20) 4. Consider the metabolism of isoleucine in a mammal in the fasting state. Assume the animal needs to make glucose and does not need to use ilu as a direct source of energy. Assume also that the animal needs to keep serum ammonia concentration at a minimum! (ilu = H3+NCH(CO2-)CH(CH3)CH2CH3).

Draw out a pathway whereby the maximum net number of ilu carbons can be incorporated into glucose. Include names &/or structures for all "branchpoint" compounds connecting pathways etc, and show all sites where oxidation/reduction and phoshorylation/dephosphorylation takes place. Indicate tissues, compartmentation and transport for your pathway (is nitrogen involved?)

(25) 5. a. Diagram the electron transport system starting with NADH and glycerol phosphate. Use circles and labels on your diagram to indicate its arrangement into complexes.

b. With which complexes is the phosphorylation of ADP to ATP associated?

c. The main complex involved in energy capture during electron transport in photophosphorylation is analogous to which complex in oxidative phosphorylation?

d. How are electrons moved between these complexes? (What links are there between them? Be specific.)

e. List three types of electron carriers found in both of the electron transport systems we discussed, and give the number of electrons each may carry in the spaces below.


 # of electrons carried




f. Name the model used to explain the coupling of electron transport to phosphorylation.

g. What are the basic premises of this model?

(20) 6. Consider the process of fatty acid oxidation in mammals.

a. In which tissues is it most important during starvation?

In which cellular compartment does it occur? ___________________

b. What is(are) the oxidizing agent(s) used in this process?

c. What are the metabolic sources of these oxidizing equivalents? Can they be provided anaerobically? Explain briefly.

d. How is a fatty acid "activated" prior to oxidation? How much does this "activation" cost (in ATP units)?

(10) 7. Consider the process of Photosynthesis.

a. What pathways are represented in this cycle?

b. What is the stoichiometry of the light reactions?

c. Briefly, what occurs in Photosystem II?

(15) 8. a. Show the reactions for the following synthesis:

serine + CO2 + NH2 ->Tetrahydrofolate-> 2 glycine

You may use an abbreviated structurefor the H4Folate molecule.

b. Outline (words or symbols) how serine could be used to provide all of the carbons required to synthesis creatine

(10) 9. a. Under what conditions will "ketone bodies" be formed in the liver?

b. What is the biological "purpose" for forming ketone bodies?

c. Explain the statement: "Ketonebodies give the liver overall control of fatty acid metabolism."

(25) 10. Briefly describe or discuss the following:

a. (10) The structure of hemoglobin, or a similar multimeric protein, in terms of the various levels and/or elements of protein structure.

b. (10) The synthesis of fat from glucose, including the sources of reducing equivalents.

c. (5) Substrate/co-factor control of the rate of aerobic metabolism.

(15) 11 a. In our discussion of nitrogen catabolism three excretory products were discussed and their uses rationalized. What are these three products and what reasons were given for their specific uses by different organisms?

b. Briefly describe/diagram the pathway used by mammals to excrete nitrogen, beginning with amino acids, such as alanine, in the liver.


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Last modified 4 May 2004