Nucleic Acids - Mock Test 55

Question 541

A substrate for enzymes of pyrimidine nucleotide biosynthesis is?

A) Allopurinol B) Tetracylin C) Chloramphenicol D) Puromycin

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Question 542

Methotrexate blocks the synthesis of thymidine monophosphate by inhibiting the activity of the enzyme?

A) Dihydrofolate reductase B) Orotate phosphoribosyl transferase C) Ribonucleotide reductase D) Dihydroorotase

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Question 543

Methotrexate blocks the synthesis of thymidine monophosphate by inhibiting the activity of the enzyme?

A) Dihydrofolate reductase B) Orotate phosphoribosyl transferase C) Ribonucleotide reductase D) Dihydroorotase

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Question 544

UTP is converted to CTP by?

A) Methylation B) Isomerisation C) Amination D) Reduction

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Question 545

d-UMP is converted to TMP by?

A) Methylation B) Decarboxylation C) Reduction D) Deamination

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Question 546

Conversion of deoxyuridine monophosphate to thymidine monophosphate is catalysed by the enzyme?

A) Ribonucleotide reductase B) Thymidylate synthetase C) CTP synthetase D) Orotidylic acid decarboxylase

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Question 547

UDP and UTP are formed by phosphorylation from?

A) AMP B) ADP C) ATP D) GTP

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Question 548

The first true pyrimidine ribonucleotide synthesized is?

A) UMP B) UDP C) TMP D) CTP

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Question 549

A cofactor in the conversion of dihydroorotate to orotic acid, catalysed by the enzyme dihydroorotate dehydrogenase is?

A) FAD B) FMN C) NAD D) NADP

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Question 550

The two nitrogen of the pyrimidine ring are contributed by?

A) Ammonia and glycine B) Asparate and carbamoyl phosphate C) Glutamine and ammonia D) Aspartate and ammonia

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