Purines and Pyrimidines

Question 1

DIfference between building purines and building pyrimidines

Answer 1

Purines
- have sugar, build base on it

Pyrimidines
- build base, then stick sugar on @ end

Question 2

6 yr old child has PKD, this is a result of which?

a. failure to breakdown pyrimidine base
b. failure to recycle/salvage purine bases
c. defect in the synthesis of pyrimadine bases
d. inhibition of conversion of ribonucleosides to deoxyribonucleosides

Answer 2

b. failure to recycle/salvage purine bases

uric acid is end product of purine degradation

Question 3

Purine or pyrimidine?

• Initial nucleotide produce is IMP
• U is converted to C as a triphosphate
• Base ring is synthesized then attached to ribose

Answer 3

Purine
Pyrimidines
Pyrimidines

Question 4

Purine synthesis start at, end at

Answer 4

Starts at PRPP
Ends at IMP

• Key regulated step:

Question 5

Pyrimidine synthesis starts at, ends at

Answer 5

Starts at CO2 and GLutamine

Ends at UMP

Question 6

Which CPS (I or II) is activated by N-acetyl glutamate?

Answer 6

CPS I

Question 7

Regulation of key enzymes are important. Does dATP have a positive or negative effect on Ribonucleotide reductase?

Answer 7

negative

prevents Rubonucleoside diphosphate –> deoxyribonucleoside diophosphate

Question 8

How do you get from dUDP to dTTP?

Answer 8

dUDP –> dUMP –> dTMP –> dTDP –> dTTP

Question 9

Purine degradation starts with, ends with

- key enzyme?

Answer 9

starts with AMP or GMP

Ends with URic acid
(PKD if recycle/salvage pathway fails)

ADA, Xanthine oxidase