Chapter 26

Question 1

Lesch Nyhan Syndrome

Answer 1

Complete deficiency in HGPRT, inability to create IMP from hypoxanthine resulting into degradation into Uric Acid (degredation of of purines)

Question 2

Gout

Answer 2

Build up of Uric Acid, prevented by allopurinol to block Xanthine Oxidase which is the enzyme responsible for the degradation of hypoxanthine to Uric Acid

Question 3

Orotic Aciduria

Answer 3

Results from defective orotate phosphoribosyltransferase and orotidine 5’-phosphate decarboxylase causing a buildup of orotic acid in urine since it cannot be synthesized into UMP

Question 4

Draw Inosine Structure

Question 5

Draw Orotic Acid

Question 6

Ribonucleotide Reductase Regulation

Answer 6

1. ATP binds to activity site
2. ATP in site S favors the formation of dTTP
3. dTTP then occupies site S favoring GDP or ADP in catalytic site C forming dGTP
4. dGTP occupies site S, favoring ADP in catalytic site C
5. dATP replaces ATP in site A turning enzyme off

Question 7

What compound does thymine form from

Answer 7

dUMP, converted by Thymidylate synthase, 5-FU inhibits this process