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Biol 4890 > Chapter 25 > Flashcards

Chapter 25 Flashcards

1
Q

? is an inhibitor of dihydrofolate reductase and causes amplification of ? genes

A

DHFR

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2
Q

Two nucleotide synthesis pathways

A

salvage pathway and de novo pathway

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3
Q

salvage pathway

A

activated ribose (PRPP) + base

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4
Q

de novo synthesis begins with formation of ? from CPS-II

A

carbamoyl-P

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5
Q

CPS three catalytic sites

A

glutamine hydrolysis, carbamic acid phosphorylation, bicarbonate phosphorylation

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6
Q

de novo synthesis of pyrimidines pathway

A

carbamoyl-p + aspartate&raquo_space; carbamoylaspartate&raquo_space; dihydroorotate&raquo_space; orotate&raquo_space; orotate + PRPP&raquo_space; orotidylate&raquo_space; uridylate

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7
Q

purpose of glutamine hydrolysis site of CPS

A

make NH3

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8
Q

catalytic power of OMP decarboxylase

A

accelerates reaction by factor of 10^7

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9
Q

charging of nucleoside monophospahate to NDP

A

requires specific nucleoside monophosphate kinase

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10
Q

charging of NDP to NTP

A

requires nonspecific nucleoside diphosphate kinase

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11
Q

Enzymes in de novo synthesis of pyrimidines

A

ATCase&raquo_space; dihydroorotase&raquo_space; dihydroorotate dehydrogenase&raquo_space;orotate phosphoribosyltransferase&raquo_space; OMP decarboxylase

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12
Q

PRPP synthetase is inhibited by ?

A

AMP, GMP , IMP

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13
Q

synthesis of CTP from UTP

A

Gln + water&raquo_space; NH3&raquo_space; NH3 + UTP +ATP&raquo_space; CTP

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14
Q

bicarbonate phosphorylation site is an example of this domain

A

grasp

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15
Q

grasp domain

A

holds for nucleophilic attack at phosphoryl group. formation of C-N bonds w/ acyl phosphate intermediates

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16
Q

? can be salvaged by a pyrimidine phosphoribosyl transferase

A

uracil

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17
Q

de novo purine synthesis

A

assembled already attached to ribose. made from IMP.

18
Q

pathway from IMP to AMP

A

IMP + GTP&raquo_space; adenylosuccinate&raquo_space; AMP + fumarate

19
Q

pathway from IMP to GMP

A

IMP + NAD+&raquo_space; xanthylate&raquo_space; xanthylate + ATP + NH3&raquo_space;guanylate

20
Q

enzymes in AMP synthesis

A

adenylosuccinate synthase, adenylosuccinate lyase

21
Q

enzymes in GMP synthesis

A

IMP dehydrogenase&raquo_space; GMP synthase

22
Q

adenylosuccinate synthase is inhinited by ?

A

AMP

23
Q

IMP dehydrogenase is inhibited by ?

A

GMP

24
Q

? analogs inhibit many amidotransferase reactions

A

glutamine

25
Q

PRPP is a ? activator of purine synthesis

A

feed forward

26
Q

ribonucleotide reductase reaction

A

ribonucleotides&raquo_space; deoxyribonucleotides

27
Q

ribonucleotide reducatse must be reduced by ? to reactivate

A

thioredoxin

28
Q

ribonucleotide reducatase regulation

A

Activity site: activated by ATP, inhibited by dATP. Specificity site: cross regulation between purines and pyrimidines

29
Q

cross regulation between purines and pyrimidines

A

purines enhance production of deoxypyrimidines. Pyrimidines enhance production of deoxypurines

30
Q

dCMP deaminase reaction

A

dCMP&raquo_space; dUMP

31
Q

thymidylate synthase reaction

A

dUMP + N5,N10-methyleneTHF&raquo_space; TMP

32
Q

inhibition of dTMP is commonly used in ?

A

chemotherapy

33
Q

? is a suicide inhibitor of thymidylate synthase

A

FluoroUMP

34
Q

inhibitors of human DHF reductase

A

folate analogs methotrexate

35
Q

in purine catabolism, ? recycles hypoxanthine and guanine

A

hypoxanthine guanine phosphoribosyltransferase

36
Q

in purine catabolism, ? recycles adenine

A

adenine phosphoribosyltransferase

37
Q

loss of adenosine deaminase results in ?

A

SCID, severe combined immunodeficiency

38
Q

high levels of dATP act to tshut off ?

A

ribonucleotide reductase

39
Q

uric acid is close to solubility limit. excess uric acid can precipitate and cause ?

A

gout

40
Q

? inhibits xanthine oxidase

A

allopurinol

41
Q

Lesch-Nyhan syndrome

A

loss HGPRT results in high levels of PRPP. Leads to high levels of purines and uric acid

Biol 4890 (16 decks)

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