Exam 18: Nucleotide Metabolism

Which of the following is NOT a general role of nucleotides in cells?

If GMP radiolabeled at the nitrogen atom indicated by the * were metabolized to uric acid,which of the following molecules along the pathway would also be radioactive?

The chemotherapy agent 5-fluorouracil is usually degraded by which of the following enzymes,which requires administration of higher doses?

If HCO₃ That is radioactively labeled with ¹³C is available,which carbon atom in the molecule below would ultimately be expected to be radioactive?

A person is carrying out in vitro synthesis of uric acid from GMP.He or she wants to include all substrates and enzymes necessary.All EXCEPT __________ should be included in the reaction mixture.

The possibility of ADA-SCID is indicated by __________ than normal activity of __________.

Which of the following is an intermediate in the conversion of AMP to uric acid but NOT an intermediate in the conversion of GMP to uric acid?

Explain how a general inhibitor of endonucleases would alter the homeostasis of mRNA and affect the nucleotide salvage pathway.

How many ATP are converted to ADP during the biosynthesis of CTP from UMP?

An enzyme panel analysis of a patient reveals a lack of __________,which is an indication of Lesch-Nyhan syndrome.

Compare the regulatory effects of ATP and CTP on ATCase in E.coli.

A mutation in the gene encoding which of the following enzymes would affect the synthesis of both AMP and GMP?

Nonprimate mammals convert uric acid to allantoin.This reaction,catalyzed by urate oxidase,also generates which of the following products?

A part of the pathway of UMP biosynthesis is shown below.What intermediate is missing? What is the enzyme that generates this compound in the pathway? What is the enzyme that uses this compound as a substrate in the pathway? Carbamoyl phosphate + Aspartate Carbamoyl aspartate __________ Orotate

The biosynthesis of CTP is allosterically regulated at many steps.Which of the following is a major point of regulation?

Contrast the binding of nucleotides to the activity site and specificity site on the R1 subunit of E.coli ribonucleotide reductase by choosing the nucleotide that can bind to the specificity site but NOT the activity site.

Reduction in dTMP biosynthesis is NOT dependent upon __________.

What enzymatic activity is NOT required during the biosynthesis of UMP from carbamoyl phosphate and aspartate?

Aspartate contains four carbons.If all are radioactively labeled,how many carbons of UMP will be radioactively labeled?

Which of the following is the precursor of the indicated carbon atom in a pyrimidine ring?