Question 13 of 16

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If a cell has an adequate supply of adenine nucleotides byt requires more guanine nucleotides for protein synthesis:

1. Glutamine-PRPP amidotransferase will not be fully inhibited.

2. AMP will be a feedback inhibitor of the condensation of IMP with aspartate.

3. ATP will stimulate the production of GMP from IMP.

4. ATP will inhibit nucleoside diphosphate reductase..

A. 1, 2 and 3

B. 1 and 3

C. 2 and 4

D. 4 only

E. All four

The correct answer is (A).

Comments:

1. The synergistic effect of both AMP and GMP is needed for complete inhibition.

2. This assures that the limited amount of IMP formed will be channeled to the production of the guanine nucleotides.

3. ATP provides the energy for this branch.

4. The formation of dATP is not applicable in this situation.

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Last modified 1/5/95