USMLE

Question 1

Purines

Answer 1

Pure AG

A
G

Question 2

Pyrimidines

Answer 2

CUT the PY

C
U
T

Question 3

Amino acid requirement for purine synthesis

Answer 3

GAG

Glycine
Aspartate
Glutamine

Question 4

Amino acid requirement for both purine and pyrimidine synthesis

Answer 4

Aspartate

Question 5

MOA of
MTX
TMP (trimethoprim)
Pyrimethamine

Answer 5

Inhibit dihydrofolate reductase

MTX - humans
TMP - bacteria
Pyrimethamine - protozoans

(pyrimidine synthesis)

Question 6

MOA of 5-FU

Answer 6

Inhibits thymidylate synthase

pyrimidine synthesis

Question 7

MOA of

6-MP and azathioprine

Answer 7

Inhibit de novo purine synthesis

Question 8

MOA of hydroxyurea

Answer 8

Inhibits ribonucleotide reductase

purine and pyrimidine synthesis

Question 9

Lesch-Nyhan syndrome absent enzyme

Answer 9

HGPRT

leads to:
Hyperuricemia
Gout
Pissed off (aggression and self-mutilation)
Retardation
T (dysTonia)

Question 10

Unambiguous genetic code features

Answer 10

Each codon specifies only 1 amino acid

Question 11

Degenerate or redundant genetic code features

Answer 11

Most AA are coded by multiple codons
EXCEPT:
Methionine - AUG (MET tayo in AUG)
Tryptophan - UGG

Question 12

Transition mutation

Answer 12

Purine to purine

Pyrimidine to pyrimidine

Question 13

Transversion mutation

Answer 13

Purine to pyrimidine

Pyrimidine to purine

Question 14

Most severe mutation

Answer 14

Frameshift

Frameshift > nonsense > missense&raquo_space; silent

Question 15

Missense mutation

Answer 15

Changed AA

Sickle cell dse (glutamate to valine)
Sick GV

Question 16

Nonsense mutation

Answer 16

Early stop codon
Nonfunctional protein

Stop this nonsense!

Question 17

Frameshift mutation

Answer 17

Deletion or insertion of nucleotides not divisible by 3
Leads to misreading of downstream nucleotides

Duchenne muscular dystrophy
Tay-Sachs dse

Question 18

Rate limiting enzyme of

Glycolysis

Answer 18

Phosphofructokinase-1 (PFK-1)

Question 19

Rate limiting enzyme of

Gluconeogenesis

Answer 19

Fructose-1,6-bisphosphatase

Question 20

Rate limiting enzyme of

TCA cycle

Answer 20

Isocitrate dehydrogenase

Question 21

Rate limiting enzyme of

Glycogenesis

Answer 21

Glycogen synthase

Question 22

Rate limiting enzyme of

Glycogenolysis

Answer 22

Glycogen phosphorylase

Question 23

Rate limiting enzyme of

HMP shunt

Answer 23

G6PD

Question 24

Rate limiting enzyme of

De novo pyrimidine synthesis

Answer 24

Carbamoyl phosphate synthetase II

Question 25

Rate limiting enzyme of

De novo purine synthesis

Answer 25

Glutamine - phosphoribosylpyrophosphate(PRPP) amid9 transferase

Question 26

Rate limiting enzyme of

Urea cycle

Answer 26

Carbamoyl phosphate synthetase I

Question 27

Rate limiting enzyme of

Fatty acid synthesis

Answer 27

Acetyl-CoA carboxylase

Question 28

Rate limiting enzyme of

Fatty acid oxidation

Answer 28

Carnitine acyltransferase I

Question 29

Rate limiting enzyme of

Ketogenesis

Answer 29

HMG-CoA synthase

Question 30

Rate limiting enzyme of

Cholesterol synthesis

Answer 30

HMG-CoA reductase

Question 31

Other name for Glycolysis

Answer 31

EMP

Embden Meyerhof Parnas

Question 32

Other name for HMP shunt

Answer 32

PPP

Pentose Phosphate Pathway

Question 33

Other name for TCA cycle

Answer 33

Citric cycle

Krebs cycle

Question 34

AA special group of guanidinium

Answer 34

Arginine, R

Question 35

AA special group of Benzene

Answer 35

Phenylalanine, F

Question 36

AA special group of Phenol

Answer 36

Tyrosine, Y

Question 37

AA special group of Indole

Answer 37

Tryptophan, W

Question 38

AA special group of Imidazole

Answer 38

Histidine

Question 39

AA special group of Pyrrolidine

Answer 39

Proline, P

imino acid