Purine Metabolism - Exam 1

Question 1

Nucleotides serve all of the following roles EXCEPT

Answer 1

Structural components of membranes

Question 2

ribose with nucleotides

Answer 2

purines built on pyrimidines built then on

Question 3

whites not a purine

Answer 3

cytosine

Question 4

which of the following does not serve as a source of C in purine ring synthesis?

Answer 4

aspartate

glutamine

Question 5

sources of nitrogen

Answer 5

2 glu
1 asp
1 gly

Question 6

sources of carbon

Answer 6

2 gly
1 CO2
2 N10-fTHF

Question 7

synthesis of PRPP

Answer 7

from ribose 5-phosphate
activated by Pi
inhibited by purines

Question 8

R 5-p is produced from glucose by

Answer 8

PPP (also produces NADPH…)

Question 9

first committed step

Answer 9

PRPP to 5-phosphoribosyl 1-amine

Question 10

rate limiting steps

Answer 10

prpp synthetase:
feedback inhibition
Glutamine PRPP amidotransferase:
AMP GMP inhibits
Stimulated by PRPP (feed forward)

Question 11

PABA analogs

Answer 11

slow down purine synthesis in bacteria

Question 12

methotrexate

Answer 12

slows down purine synthesis in humans

Question 13

methotrexate affects nucleotide synthesis by limiting THF by inhibiting

Answer 13

dihydrofolate reductase

Question 14

first purine nucleotide

Answer 14

IMP (base or ring is hypoxanthine)

Question 15

needed for AMP synthesis

Answer 15

GTP

Question 16

needed for GMP synthesis

Answer 16

ATP

Question 17

mycophenolic acid

Answer 17

immunosupressent for graft rejection

Question 18

electron source for ribonucleotide reductase (RNR)

Answer 18

NADPH

Question 19

most purine synthesis occurs in

Answer 19

liver

most ingested are degraded and excreted

Question 20

PNP deficiency

Answer 20

IMMUNODEFICIENCY

Question 21

ADA deficiency

Answer 21

SCID

Question 22

PRTs

Answer 22

HG and A h=hypoxanthine

Question 23

defective HGPRTase

Answer 23

Lesch-Nyhan
gouty
self-mutilation
retardation
lip and finger biting!!

Question 24

uric acid is

Answer 24

formed from xanthine in the presence of O2

Question 25

Hyperuricemia

Answer 25

progresses to gout
lactic acidosis, lead both interfere with excretion
PRPP working overtime…

Question 26

gout - DX

Answer 26

negative birefringent urate crystals in the synovial fluid

Question 27

kidney stones

Answer 27

can be same

Question 28

gout - TX

Answer 28

allopurinol

low purine diet

Question 29

Lesch-Nyhan is due to the inability to catalyze which reaction

Answer 29

guanine to GMP

Question 30

SCID

Answer 30

ADA def
B, T, and NK cells can’t divide
must diagnose early