Cramming 1

Question 1

How do DNA mismatch repair enzymes distinguish between the old and new strands of DNA (DNA replication)?

Answer 1

Template strand is methylated at cytosine and adenine residues.

Question 2

What immunosuppressant drug inhibits Inosine Monophosphate d.h.?

Answer 2

mycophenolate

Question 3

What immunosuppressant drug inhibits PRPP synthetase?

Answer 3

6-MercaptoPurine

Question 4

What immunosuppressant drug inhibits dihydrofolate reductase?

Answer 4

MTX

Question 5

Which antibiotic inhibits dihydrofolate reductase?

Answer 5

TMP

Question 6

Which immunosuppressant inhibits ribonucleotide reductase?

Answer 6

5-fluorouracil

Question 7

What does reactrion does ribonucleotide reductase catalyze?

Answer 7

UDP –> dUDP

Question 8

What enzyme deficiencies would give you orotic aciduria? How would you differentiate them?

Answer 8

orotic acid phosphoribosyltransferase or 5’-phosphate decarboxylase def: megaloblastic anemia
OR
OTC def: hyperammonemia

Question 9

What immunosuppressant drug toxicity will increase with co-administration of allopurinol?

Answer 9

6-MP and azothioprine

Question 10

What do single stranded binding proteins do?

Answer 10

prevent strands from re-annealing during DNA replication

Question 11

What does the anti-Scl-70 Ab, seen in systemic scleroderma, target?

Answer 11

Topoisomerase I

Question 12

What Ab is characteristic of CREST syndrome?

Answer 12

anti-centromere

Question 13

What is the intracellular target of doxo- and daunorubicin?

Answer 13

Topoisomerase II (aka DNA gyrase)

Question 14

What antibiotics target prokaryotic DNA gyrase?

Answer 14

fluoroquinolones

Question 15

DNA replication: exonuclease or endonuclease?

Answer 15

EXOnuclease

Question 16

Nucleotide excision repair: exonuclease or endonuclease?

Answer 16

ENDOnuclease

Question 17

What is the primary defect in ataxia telangiectasia?

Answer 17

nonhomologous end joining (repair of double-stranded DNA breaks)

Question 18

What would be the result of a mutation in the promoter?

Answer 18

dramatic decrease in transcription of the gene

Question 19

What is the mech of alpha-amanatin, the toxin of the death cap mushroom that can cause liver failure if ingested?

Answer 19

inhibits RNA Pol II

Question 20

Where does the aa attach to the tRNA? What 3-nucleotide sequence is present here?

Answer 20

3’ end; CCA (Can Carry Amino acids.)

Question 21

Streptomycin and gentamicin are examples of _______ Abx, which target _______.

Answer 21

aminoglycosides; 30S ribosomal subunit