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Flashcards in USMLE Deck (39):
1

Purines

Pure AG

A
G

2

Pyrimidines

CUT the PY

C
U
T

3

Amino acid requirement for purine synthesis

GAG

Glycine
Aspartate
Glutamine

4

Amino acid requirement for both purine and pyrimidine synthesis

Aspartate

5

MOA of
MTX
TMP (trimethoprim)
Pyrimethamine

Inhibit dihydrofolate reductase

MTX - humans
TMP - bacteria
Pyrimethamine - protozoans

(pyrimidine synthesis)

6

MOA of 5-FU

Inhibits thymidylate synthase
(pyrimidine synthesis)

7

MOA of
6-MP and azathioprine

Inhibit de novo purine synthesis

8

MOA of hydroxyurea

Inhibits ribonucleotide reductase
(purine and pyrimidine synthesis)

9

Lesch-Nyhan syndrome absent enzyme

HGPRT

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

10

Unambiguous genetic code features

Each codon specifies only 1 amino acid

11

Degenerate or redundant genetic code features

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

12

Transition mutation

Purine to purine
Pyrimidine to pyrimidine

13

Transversion mutation

Purine to pyrimidine
Pyrimidine to purine

14

Most severe mutation

Frameshift

Frameshift > nonsense > missense >> silent

15

Missense mutation

Changed AA

Sickle cell dse (glutamate to valine)
Sick GV

16

Nonsense mutation

Early stop codon
Nonfunctional protein

Stop this nonsense!

17

Frameshift mutation

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

Duchenne muscular dystrophy
Tay-Sachs dse

18

Rate limiting enzyme of
Glycolysis

Phosphofructokinase-1 (PFK-1)

19

Rate limiting enzyme of
Gluconeogenesis

Fructose-1,6-bisphosphatase

20

Rate limiting enzyme of
TCA cycle

Isocitrate dehydrogenase

21

Rate limiting enzyme of
Glycogenesis

Glycogen synthase

22

Rate limiting enzyme of
Glycogenolysis

Glycogen phosphorylase

23

Rate limiting enzyme of
HMP shunt

G6PD

24

Rate limiting enzyme of
De novo pyrimidine synthesis

Carbamoyl phosphate synthetase II

25

Rate limiting enzyme of
De novo purine synthesis

Glutamine - phosphoribosylpyrophosphate(PRPP) amid9 transferase

26

Rate limiting enzyme of
Urea cycle

Carbamoyl phosphate synthetase I

27

Rate limiting enzyme of
Fatty acid synthesis

Acetyl-CoA carboxylase

28

Rate limiting enzyme of
Fatty acid oxidation

Carnitine acyltransferase I

29

Rate limiting enzyme of
Ketogenesis

HMG-CoA synthase

30

Rate limiting enzyme of
Cholesterol synthesis

HMG-CoA reductase

31

Other name for Glycolysis

EMP
Embden Meyerhof Parnas

32

Other name for HMP shunt

PPP
Pentose Phosphate Pathway

33

Other name for TCA cycle

Citric cycle
Krebs cycle

34

AA special group of guanidinium

Arginine, R

35

AA special group of Benzene

Phenylalanine, F

36

AA special group of Phenol

Tyrosine, Y

37

AA special group of Indole

Tryptophan, W

38

AA special group of Imidazole

Histidine

39

AA special group of Pyrrolidine

Proline, P
(imino acid)