9 Questions
What is the primary outcome of inhibition of dihydroorotate dehydrogenase in pyrimidine synthesis?
Inhibition of dihydroorotate dehydrogenase prevents the formation of orotate, which is a crucial step in pyrimidine synthesis.
How does 5-fluorouracil (5-FU) inhibit thymidylate synthesis?
5-FU is converted to 5-F-dUMP, which inhibits thymidylate synthase, thereby preventing the formation of dTMP.
What is the primary effect of azathioprine on purine synthesis?
Azathioprine is metabolized to 6-MP, which inhibits de novo purine synthesis by inhibiting guanine phosphoribosyltransferase.
How do mycophenolate and ribavirin inhibit purine synthesis?
Mycophenolate and ribavirin inhibit inosine monophosphate dehydrogenase, which is essential for the de novo synthesis of purines.
What is the primary effect of hydroxyurea on nucleotide synthesis?
Hydroxyurea inhibits ribonucleotide reductase, which is essential for the conversion of ribonucleotides to deoxyribonucleotides.
How does methotrexate (MTX) inhibit nucleotide synthesis?
MTX inhibits dihydrofolate reductase, which is essential for the conversion of dihydrofolate to tetrahydrofolate, a cofactor required for nucleotide synthesis.
What is the primary effect of 6-mercaptopurine (6-MP) on purine synthesis?
6-MP inhibits de novo purine synthesis by inhibiting guanine phosphoribosyltransferase.
What is the role of carbamoyl phosphate synthetase II (CPS2) in pyrimidine synthesis?
CPS2 is involved in the conversion of glutamine and CO₂ to carbamoyl phosphate, which is a precursor of orotic acid.
What is the primary outcome of impaired orotic aciduria?
Impaired orotic aciduria leads to a deficiency in pyrimidine synthesis, resulting in impaired nucleotide synthesis.
This quiz covers the molecular biology of de novo pyrimidine and purine synthesis, including the role of various drugs and the salvage pathway. It also explores the production of pyrimidine and purine bases, including the required molecules and enzymes.
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