FIRST AID - BIOCHEM 1 QUESTIONS
WITH VERIFIED ANSWERS [GRADED
A+]
template cytosine and adenine - ✔✔these are methylated during DNA
replication to distinguish old from new strands
histone acetylation - ✔✔this relaxes DNA coiling allowing for transcription
A and G ; C, T, U - ✔✔these are purine NT ; these are pyrimidines
cytosine - ✔✔deamination of this NT makes uracil
thymine ; guanine - ✔✔this NT has a methyl group ; this purine has a
ketone
©morren2025/2026.Year published 2026.
,glycine, aspartate, glutamine - ✔✔these amino acids are necessary for
purine synthesis
aspartate, carbamoyl phosphate - ✔✔components needed to make
pyrimidines
PRPP (sugar and phosphate) ; 6 mercaptopurine - ✔✔starting point for de
novo purine synthesis ; what inhibits this?
Ribose 5P -> PRPP -> IMP -> AMP and GMP - ✔✔steps in purine
synthesis
Carbamoyl phosphate --> orotic acid (temporary base) + PRPP -> UMP ->
UDP -> CTP and dUDP -> dUMP -> dTMP - ✔✔steps in pyrimidine
synthesis
pyrimidine synthesis and urea cycle ; ornithine transcarbamoylase - ✔✔2
cycles that use carbamoyl phosphate ; what enzyme will cause build up of
it if deficient?
©morren2025/2026.Year published 2026.
, hydroxyurea - ✔✔this inhibits ribonucleatide reductase (in pyrimidine
synthesis)
inhibition thymidylate synthase -> decreased dTMP - ✔✔effect of 5-FU on
pyrimidine synthesis
dihydrofolate reductase (reduced dTMP) - ✔✔what does methotrexate
inhibit?
UMP synthase ; can't convert orotic acid to UMP - ✔✔this is defective in
orotic acuduria ; what is effect?
orotic acid in urine (w/o hyperammonemia), megaloblastic anemia, failure
to thrive ; oral uridine - ✔✔findings in orotic aciduria (UMP synthase
defect) ; what is treatment?
©morren2025/2026.Year published 2026.
WITH VERIFIED ANSWERS [GRADED
A+]
template cytosine and adenine - ✔✔these are methylated during DNA
replication to distinguish old from new strands
histone acetylation - ✔✔this relaxes DNA coiling allowing for transcription
A and G ; C, T, U - ✔✔these are purine NT ; these are pyrimidines
cytosine - ✔✔deamination of this NT makes uracil
thymine ; guanine - ✔✔this NT has a methyl group ; this purine has a
ketone
©morren2025/2026.Year published 2026.
,glycine, aspartate, glutamine - ✔✔these amino acids are necessary for
purine synthesis
aspartate, carbamoyl phosphate - ✔✔components needed to make
pyrimidines
PRPP (sugar and phosphate) ; 6 mercaptopurine - ✔✔starting point for de
novo purine synthesis ; what inhibits this?
Ribose 5P -> PRPP -> IMP -> AMP and GMP - ✔✔steps in purine
synthesis
Carbamoyl phosphate --> orotic acid (temporary base) + PRPP -> UMP ->
UDP -> CTP and dUDP -> dUMP -> dTMP - ✔✔steps in pyrimidine
synthesis
pyrimidine synthesis and urea cycle ; ornithine transcarbamoylase - ✔✔2
cycles that use carbamoyl phosphate ; what enzyme will cause build up of
it if deficient?
©morren2025/2026.Year published 2026.
, hydroxyurea - ✔✔this inhibits ribonucleatide reductase (in pyrimidine
synthesis)
inhibition thymidylate synthase -> decreased dTMP - ✔✔effect of 5-FU on
pyrimidine synthesis
dihydrofolate reductase (reduced dTMP) - ✔✔what does methotrexate
inhibit?
UMP synthase ; can't convert orotic acid to UMP - ✔✔this is defective in
orotic acuduria ; what is effect?
orotic acid in urine (w/o hyperammonemia), megaloblastic anemia, failure
to thrive ; oral uridine - ✔✔findings in orotic aciduria (UMP synthase
defect) ; what is treatment?
©morren2025/2026.Year published 2026.
