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biochem 2 > Nucleotide metabolism > Flashcards

Nucleotide metabolism Flashcards

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1
Q

nucleoside

A

linking a nitrogenous base to the 1’ position of the ribose ring

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2
Q

nucletodie

A

nucleoside added to phosphate at 5’ position of ribose ring

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3
Q

deoxyribonucleotide

A

hydroxyl group at 2’ position of ribose ring is replaced with H

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4
Q

de novo synthesis

A

makeing nucleotide from scratch

takes a lot of energy

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5
Q

salavage pathways

A

generation of nucleotides from free bases and nucleosides from diet

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6
Q

first step in purine synthesis

A

PRPP generation

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7
Q

committed step of purine synthesis

A

amidophosphoribosyltransferase forming PRA from PRPP

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8
Q

what is the first purine syntheiszed

A

IMP

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9
Q

what is IMP a precusor for

A

synthesis of both AMP and GMP

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10
Q

how are carbon and/or nitrogen atoms donating to de novo pathway

A

amino acids

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11
Q

what provides carbon and oxygen to de novo pathway

A

CO2

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12
Q

what serves as a donor of one-carbon groups to de novo pathway

A

N10-formyl THF

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13
Q

what is the rate limiting enzyme of GMP synthase

A

IMP dehydrogenase

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14
Q

what inhibits IMP dehydrogenase

A

GMP

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15
Q

what is the rate limiting enzyme of AMP synthesis

A

adenylosuccinate synthase

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16
Q

what inhibits adenylosuccinate synthase

A

AMP

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17
Q

how do AMP and GMP get converted into ATP and GTP

A

nucleoside 5’ monophosphate kinases and nucleoside 5’diphosphate kinases

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18
Q

what inhibits PRPPP synthetase

A

ADP and GDP

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19
Q

what is PRPP required for

A

synthesis of both purines and pyrimidines

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20
Q

what inhibits amidophosphoribosyltransferase

A

AMP and GMP

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21
Q

when is de novo purine synthesis limited

A

when purine nucleotides are abudent

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22
Q

incrase in PRPP do waht

A

stimulate de novo synthesis

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23
Q

what is the end product of purine metabolism

A

uric acid

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24
Q

how is uric acid excreted

A

kidney

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25
hyperuricemia
excess uric acid in blood
26
what cause can reduced excretion of uric acid
renal insufficieny | metabolic acidosis
27
what can cause incrased production of uric acid
increased nucleotide turnover | diet rich in purine
28
how does EtOH affect uric acid
causes decreases excertion and increased production
29
is uric acid soluble or insoluble
insoluble
30
what is a possible consquence of increased uric acid
crystals of sodium urate deposite in joints, cause gouty arthritis
31
how do you treat hyperuricemia
allopurinol
32
how does allopurinol work
gets metabolized to oxypurinol which is a compoetitive inhibitor of xanthine oxidase
33
where does the synthesis of UMP take place
5 steps in cytoplasm, one in mitochondria
34
what is the first step in UMP synthesis
carbamoyl phosphate synthetase II
35
how do you get OMP to UMP
OMP decarbozylase
36
what are the first 3 steps of ump synthesis catalyzed by
CAD
37
what are teh last 2 steps of UMP synthase catalyzed by
UMP synthase
38
what causes orotic aciduria
defect in UMP synthase
39
symptoms of orotic aciduria
symptoms similiar to megaloblastic anemia
40
how do you treat orotic aciduria
pyrimidine supplementation
41
how do you get UTP to CTP
CTP synthase,
42
what does CTP use as a amino group donor
glutamine
43
how does UTP affect CTP synthase
as UTP levels increase, enzyme becomes more efficient at binding UTP
44
how does CTP affect CTP synthase
negative feedback
45
what catalyzes synthesis of deoxyribonucleutides
ribonucleotide reductase
46
what gets oxidized during ribonucleotide reductase
thioredoxin
47
wha tinhibits ribonucletodie reductase
hydroxyurea
48
what causes SCID
mutation in adenosine deaminase
49
do cells contain ribonucletodies of thymine
no
50
what catalyzes synthesis of dTMP
thymidylate syntahse
51
what happens when you inibt thymidylate synthase
prevent cell proliferation
52
inhibitor of thymidylate synthase
5-flurorourical
53
what happens when you degrate pyrimidine nucletodies
beta-amino acids
54
what is unique to thymine degration
beta-aminoisobutryate proudction
55
where does most de novo synthesis of nucleotides take palce
liver
56
what 2 enzymes do salavage of bases require
HGPRTase and APRTase
57
how do you get IMP in salaver pathway
hypoxanthine + PRPP
58
how do you get GMP in salvage pathway
Guanine + PRPP
59
how do you get AMP in salvage pathway
Adenine + PRPP
60
how does generation of IMP, GMP, and AMP by salvage pathways affect de novo synthesis
decreases it
61
what is lesch-nyhan syndrome caused by
deficeny of HGPRTase activity
62
symptoms of lesch-nyhan syndrome
hyperuricemia, uric acid stones, intellectual disablity, biting of fingers/lipis
63
what catalyzes pyrimidine bases and nucleosides
pyrimidine phosphoribosyltranserase
64
is cytosin salvaged in humans
no
65
what inhbiits CTP synthase
CTP
66
what inhbiits ribonucleotide reductase
NTPs and dNTPs
67
what inhbiits hypoxanthine guanine phosphoribosyltransferase
IMP and GMP
68
what inhibits adenine phosphoribosyltransferase
AMP

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