Nucleotide metabolism

Question 1

Rate-limiting enzyme of
purine synthesis

Answer 1

PRPP glutamyl amidotransferase

Question 2

Rate-limiting enzyme of
pyrimidine synthesis

Answer 2

Carbamoyl phosphate
synthetase II

Question 3

Atom donors of purine molecules

Answer 3

Glutamine, Aspartate,
Carbon dioxide, Glycine,
N10-formyltetrahydrofolate

Question 4

Atom donors of pyrimidine
molecules

Answer 4

Glutamine, Aspartate,
Carbon dioxide

Question 5

Donor of ribose-5-phosphate
involved in purine and
pyrimidine synthesis

Answer 5

Phosphoribosyl
pyrophosphate (PRPP)

Question 6

Structural analogs of PABA
that competitively inhibit
dihydropteroate synthase

Answer 6

Sulfonamides

Question 7

Structural analog of folate,
selectively inhibits bacterial
dihydrofolate reductase

Answer 7

Trimethoprim

Question 8

Metabolically converted to 5-
FdUMP, which inhibits
thymidylate synthase

Answer 8

5-fluorouracil

Question 9

Inhibits dihydrofolate
reductase, which reduces
the tetrahydrofolate supply
for the synthesis of thymine

Answer 9

Methotrexate

Question 10

Reversible inhibitor of IMP
dehydrogenase, depriving T
and B lymphocytes of
nucleic acids

Answer 10

Mycophenolate