Which statement accurately describes the initial committed step in de novo purine nucleotide synthesis?

Correct answer: An amino group from glutamine is attached at C-1 of PRPP.

Explanation

The de novo synthesis of purine nucleotides begins with the formation of 5-phosphoribosylamine from PRPP and glutamine. This reaction, catalyzed by glutamine-PRPP amidotransferase, is the first committed step and a major point of regulation for the entire pathway.

Other questions

Question 1

What is the primary function of leghemoglobin in the root nodules of leguminous plants during nitrogen fixation?

Question 2

What is the net reaction for the combined action of glutamine synthetase and glutamate synthase in bacteria and plants?

Question 3

According to the text, which of the following is NOT a characteristic of the regulation of E. coli glutamine synthetase?

Question 4

What is the primary role of the coenzyme 5-phosphoribosyl-1-pyrophosphate (PRPP) in amino acid biosynthesis?

Question 5

The biosynthesis of serine from 3-phosphoglycerate involves which sequence of general reactions?

Question 6

In the catabolism of heme, what is the role of heme oxygenase?

Question 7

What is the primary role of the coenzyme S-adenosylmethionine (adoMet)?

Question 8

What is the consequence of the irreversibility of the reaction converting N5,N10-methylenetetrahydrofolate to N5-methyltetrahydrofolate in the context of vitamin B12 deficiency?

Question 9

Which amino acid is NOT a member of the biosynthetic family derived from alpha-ketoglutarate?

Question 10

What is the key structural feature of the enzyme glutamine amidotransferase?

Question 12

How do mammals primarily synthesize phosphatidylethanolamine and phosphatidylcholine?

Question 13

What is the primary mechanism by which the drug allopurinol treats gout?

Question 14

What is the role of thioredoxin in the synthesis of deoxyribonucleotides?

Question 15

What is the key difference between the de novo biosynthetic pathways for purines and pyrimidines?

Question 16

How many ATP molecules are consumed in the overall reaction for biological nitrogen fixation to produce two molecules of ammonium ion?

Question 17

What is the source of the five-carbon skeleton for the amino acid proline?

Question 18

What is the role of allopurinol's metabolite, oxypurinol, in the treatment of gout?

Question 19

The drug methotrexate is a potent inhibitor of which enzyme?

Question 20

The disease Lesch-Nyhan syndrome is caused by a genetic lack of which enzyme activity?