Nucleotide metabolism: one-carbon donor for purine ring: practice question

The best answer is A, N10-formyl tetrahydrofolate. N10-formyl tetrahydrofolate donates the formyl carbons that become C2 and C8 of the purine ring.

N5,N10-methylene tetrahydrofolate supplies the methyl group for thymidylate.

N5-formimino tetrahydrofolate arises from histidine catabolism and is converted to the methenyl form.

N5-methyl tetrahydrofolate donates its methyl group to homocysteine via methionine synthase.

It tests Nucleotide metabolism: one-carbon donor for purine ring in Biochemistry. N5,N10-methylene tetrahydrofolate is the donor for thymidylate synthase, and N5-methyl tetrahydrofolate is used to remethylate homocysteine. Folate deficiency therefore impairs both purine and thymidylate synthesis.

We tag it as an application question: it asks you to use a fact on a patient or a finding. The tag is our own editorial judgement, not an official difficulty rating, so read the reason for every option, not only the answer.

Build one table of enzyme deficiency, disease, inheritance and key finding, then revise it by spaced recall. Then use the flashcards and the other Biochemistry questions on this site to test what stuck.

No. It is an original practice item (editorial status: sample, version 1). NextPrep does not publish recalled or leaked questions, and independent faculty review of this item has not been completed yet, so confirm important facts in a standard textbook.