Exam 18: Nucleotide Metabolism

How would the flux of the pyrimidine biosynthetic pathway in E.coli cells be affected if the enzyme level of PRPP synthetase is upregulated? Explain your reasoning.

The enzymes required to convert PRPP to IMP in animal cells form a large protein complex called a(n)__________.Describe the experimental evidence proving the existence of this complex.

Distinguish between the enzyme requirements for the regeneration of NADP⁺ needed during dNDP formation in humans and bacteria.

Samples from a bird,reptile,amphibian,and primate were analyzed by Western blotting for the expression of allantoinase,the enzyme that converts allantoin to allantoic acid.Unfortunately the researcher forgot the order that the samples were loaded into the gel.Luckily,only a single sample indicated allantoinase.Which sample contained allantoinase?

Order the following steps involving the regeneration of ribonucleotide reductase that occurs in most animals so that it may carry out the formation of deoxyribonucleotides.(Note that not all steps are shown.) 1)Reduction of thioredoxin 2)Reduction of ribonucleotide reductase 3)Oxidation of thioredoxin reductase 4)Reduction of thioredoxin reductase

A compound is added to a cell and dihydrofolate reductase activity is reduced.If this compound is __________,it can be predicted that a similar result would be seen if __________ were added instead.

Identify the error in the diagram of the regulation of flux through the pyrimidine biosynthetic pathway shown below.

In severe combined immunodeficiency disease (SCID),ribonucleotide reductase activity is __________ because of an overabundance of __________.

To synthesize nucleotide monophosphates from oligonucleotides in a test tube,which enzyme must be included in the reaction mixture?

Place the steps converting GMP to uric acid in the correct order. A.Conversion to guanine B.Conversion to guanosine C.Conversion to xanthine D.Conversion to uric acid

In purines,__________ nitrogen atoms and __________ carbon atoms originate from glycine.

CTP synthetase is inhibited by __________ and activated by __________.

The oxidation of dihydroorotate to orotate,which occurs during the biosynthesis of UMP,uses what molecule as an electron acceptor?

Dihydropyrimidine dehydrogenase deficiencies exist in approximately __________ of humans and can result in complications when 5-fluorouracil is administered as a __________ therapy.

Contrast the role of kinases and nucleotidases in the nucleotide salvage pathway.

The conversion of ribose-1-phosphate to ATP via the salvage pathway would require the activity of several enzymes.Choose the answer that lists them in the order that they would act in this pathway.

If a mutation of the decarboxylase enzyme that functions in the biosynthetic pathway of UMP caused the pathway to halt at that step,which of the following would no longer occur?

An in vitro experiment with all precursors available for the conversion of dUMP to dTMP would also need to include thymidylate synthase and two additional enzymes necessary for the regeneration of N⁵,N¹⁰-methylenetetrahydrofolate.What are the two enzymes?