Nucleotide Syn/Salvage

Question 1

Carbon sources of purine bases

Answer 1

Question 2

Conversion of Ribose-5-phosphate
to PRPP

Answer 2

Question 3

Comitted step in purine synthesis

Answer 3

Question 4

Common precursor of AMP and GMP

Answer 4

IMP

Question 5

Regulation of purine synthesis

Answer 5

Question 6

Carbon sources of pyrimidine ring

Answer 6

Question 7

Regulation of pyrimidine synthesis

Answer 7

Question 8

Conversion of NDP to NTP

Answer 8

Question 9

Orotic aciduria

Answer 9

Question 10

Synthesis of dNDPs from NDPs

Answer 10

Question 11

Regulation of ribonucleotide reductase

Answer 11

Question 12

Pharm. targeting of deoxyribonucleotide synthesis

Answer 12

Question 13

Purine Salvage

Answer 13

Question 14

Catabolism of _______ leads to increased levels of urate

Answer 14

Purine catabolism

Question 15

Causes of hyperurecemia and gout

Answer 15

Question 16

Tx of gout

Answer 16

Question 17

What leads to heriditary OA?

Answer 17

Question 18

Lesch-Nyhan Syndrome

Answer 18

Question 19

Defects in what two enzymes of the purine degredation pathway leads to immunodeficiency?

Answer 19

Question 20

Megaloblastic anemia

Answer 20

Question 21

What amino acid becomes essential in Pt’s w/ phenylketonuria (PKU)?

Answer 21

Tyrosine

Phenylalanine hydroxylase normally converts phe into tyr

Question 22

What step in catecholamine synthesis requires B6?

Answer 22

DOPA decarboxylase catalyzes the conversion of L-DOPA to dopamine in the presence of the cofactor pyridoxal phosphate

B6 also found in cystathionine synthesis, heme synthesis, decarboxylation, and transamination reactions.

Question 23

How does oraganic acidemia cause hyperammonemia?

Answer 23

By inhibiting the urea cycle

Also inhibits gluconeogenesis and promotes the oxidation of fatty acids to ketone bodies (results in ketotic hypoglycemia)

Question 24

Alkaptonuria

Answer 24

Caused by a deficiency of homogentisate oxidase, an enzyme that converts homogentisate (HGA) to maleylacetoacetate. Affected individuals are usually asymptomatic in childhood but may excrete urine that turns dark if left standing (due to oxidation of accumulated HGA).

Eventually, HGA deposition in tissues throughout the body leads to connective tissue discoloration (e.g., bluish-black discoloration of ear cartilage and sclerae) and organ damage, with manifestations such as arthritis, nephrolithiasis, and coronary artery disease.

Treatment of alkaptonuria involves a diet low in tyrosine and phenylalanine, which reduces the formation of HGA.