Memetabolsim of nuclotides-pyrimidne and purine

Question 1

what are the atoms of pruine ring contributed by

Answer 1

aas (asparatate, glycine and glutamine)

CO2

n10-formyltetrahydrofolate

Question 2

where is the purine ring constructed

Answer 2

in liver by series that add the carbons and nitrogens to ribose-5-phospgate

Question 3

act and inhi of PRPP SYNTHASE

Answer 3

act: inorganic phosphate
inhi: pruine nuclotides

Question 4

act and inhi GPAT

Answer 4

inihi: amp and gmp

act: controlled by intracellular concentration of PRPP

Question 5

what inginit adenosine and guanosine monophospahte synthesis

Answer 5

by end product of that pathway

Question 6

inhibitor of imp dehydrogenase and adenylosuccinate synthetase

Answer 6

revrsible inhibitor, mycophenolic acid

Question 7

what is lesch nyhan syndrome

Answer 7

• xlinked disorder
  deficiency of HGPRT –>result in inability to salvage hypoxanthine of G form which excessive amounts of uric acid is produced.

+ cause increased PRPP lvl and decreased IMP and GMP levels

Question 8

what is regulative step in purine synthesis

Answer 8

GPAT

Question 9

what is lesch nyhan a cause of and what does it resykt form

Answer 9

. The combination of decreased purine reutilization
and increased purine synthesis results in increased
degradation of purines and the production of large amounts
of uric acid, making HGPRT deficiency an inherited cause of
hyperuricemia

rsult in formation of uric acid stones in kidneys adn urate crustals in joints and soft tissues.

characteri: motor dysfunction, cognitive deficits, behavioral disturbances

Question 10

what inhibit and act ribonucleotide reductase

Answer 10

inhi: dATP, hydroxyurea
act: ATP

Question 11

where does purine nucleotide degradation occur

Answer 11

small intestine, where pancreatic nucleases hydrolyze them to nuclotides

Question 12

what is gout initiated by + treatment

Answer 12

high levels of uric acid in blood (hyperuricemia) as result of either overproduction or underexcretion of uric acid

treatment: allopurinol inhibits xanthine oxidase, resulting in accumulation of hypoxanthine

Question 13

what can hyperuricemia lead to

Answer 13

monosodium uraye crystals in joints

inflammatory response to cyrstals

uric acid stones in kidney

Question 14

hyperuricemia-result fo

Answer 14

• decreased salvage of hypoxanthine and G and the subsequent increased availability of PRPP
• consequence of increased availability of purines

unrelated metabolic diseases, such as von Gierke disease or hereditary fructose
intolerance

Question 15

what is the regualting step in pyrimidine synthesis

ihibiton and act

Answer 15

mammalian cellS: Synthesis of carbamoyl phosphate form GLUTAMINE AND CO2, catalyzed by CPSII.

inhi: UTP
act: PRPP

Question 16

difference between CPSI(urea) and CPSII(pyrimidine)

Answer 16

CPS1:
-located in mitrochondria
- involved in ura cucle
- source is ammonia (nitrogen source)
- regualtors: act is N-acetylglutamate

CPSII:
- in cytosol
-pyrimidine synthesis
- Y-amide group of glutamine (nitrogen source)
- regulators: act is PRPP, inh is UTP

Question 17

when is the pyrimidine ring closed and what is redced here

Answer 17

• dihyroorotase
• dihydroorotate–>orotic acid = FMN is reduced

Question 18

what is the ribose 5 phos donor in pyrimidien

Answer 18

PRPP

Question 19

what are inhibitors of thymylate syntahse

Answer 19

t analogs like 5-flurouracil

Question 20

dhf reductase inhibbtiors

Answer 20

folate aalogs like methotrexate