march 21

Question 1

nucleases….

Answer 1

break phosphodiester bond to form nucleotides

Question 2

functions of nucleotides

Answer 2

Precursors of dna and rna
atp - energy currency in biological systems
adenosine nucleotides - components of 3 major enzymes
activated intermediates in many biosynthetic pathways
metabolic and physiologic regulators

Question 3

two pathways for biosynthesis of purine nucleotides

Answer 3

de novo pathway, salvage pathway

Question 4

first step of de novo pathway

Answer 4

r5p to phosphoribosylpyrophosphate

Question 5

Gout

Answer 5

characterized by high blood levels of uric acid due to overproduction or underexcretion of uric acid (in joints) (treaments drugs: allopurinol, dietary and alcohol restriction)

Question 6

lesch nyhan syndrome

Answer 6

hgprt activity deficiency
x linked
- purines not salvaged
- de novo increases
- PRPP increases
- IMP and GMP drop
     - so more substrate for Gln-PRPP amidotransferase & less inhibition form end products
          - so increased synthesis and decreased utilization leads to high uric acid

Question 7

rate-limiting step in pyrimidine synthesis

Answer 7

synthesis of carbomoyl phosphate

Question 8

CPS 1
Metabolic process
Location
N donor
Regulatory process

Answer 8

urea synthesis
mitochodrial matrix
NH4+
(+) N-acetylGlu
(+) Arginine

Question 9

CPS II

Answer 9

Pyrimidine nucleotide synthesis
cytosol
Gln
(-) UTP
(+) ATP; PRPP

Question 10

PRPP

Answer 10

activated form of ribose, always used as a precursor for making nucleotides

Question 11

orotate

Answer 11

first pyrimidine like product