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biochem 2 final > nucleotides and nucleic acids > Flashcards

nucleotides and nucleic acids Flashcards

1
Q

what are the 4 uses of nucleotides?

A

precursors for nucleic acids (DNA, RNA)
make derivatives for biochemical processes (UDP-glucose)
components of signaling pathways (cAMP)
energy source (ATP, GTP)

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2
Q

what are the ribonucleosides?

A

adenosine
guanosine
cytidine
uridine

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3
Q

what are the deoxyribonucleosides?

A

deoxyadenosine
deoxyguanosine
deoxycytidine
thymidine

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4
Q

what are the 2 methods of synthesizing nucleotides?

A

de novo synthesis

salvage pathway

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5
Q

what is the de novo synthesis pathway

A

start from scratch
purines- start with ribose and add piece by piece
pyrimidines- form base piece by piece and add to ribose

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6
Q

what is the salvage pathway?

A

recycle preformed bases from degradation of old nucleotides

add a ribose unit

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7
Q

we form deoxyribonucleotides by reducing a ribonucleotide using what enzyme?

A

ribonucleotide reductase

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8
Q

de novo pathways form?

A

ribonucleotides

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9
Q

what is an activated pentose required for de novo synthesis and salvage of both purines and pyrimidines

A

5-phosphoribosyl-1-pyrophosphate

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10
Q

ribose-5-phosphate ->

A

PRPP

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11
Q

where does purine synthesis happen?

A

primarily the liver

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12
Q

PRPP is derived from?

A

ribose-5-phosphate

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13
Q

what is the process of purine de novo synthesis?

A

start with PRPP
build the purine base on the ribose
form a purine nucleotide

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14
Q

what is the AA needed in the committed step of purine synthesis?

A

glutamine

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15
Q

IMP (inosine monophosphate) is the starting material for both?

A

AMP

GMP

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16
Q

what is the primary location for de novo synthesis of purines and can supply purines to peripheral tissues?

A

liver

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17
Q

non-hepatic has little to do with de novo synthesis and instead relies on?

A

salvage pathways

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18
Q

how does purine salvage pathway happen?

A

normal cell turnover

degradation/breakdown of nucleotides into bases

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19
Q

what enzymes are needed for the purine salvage pathway?

A

phosphoribosyltransferases

A-PRT
HG-PRT

20
Q

the purine salvage pathway uses more or less ATP?

A

less ATP; it is a significant source of purines

21
Q

hypoxanthine inhibits the _______ ________ of de novo synthesis

A

committed step

22
Q

purine salvage pathway recovers bases from breaking down ______ and _______ or turnover of _______ from diet

A

DNA, RNA, nucleotides

23
Q

purine synthesis pathway attaches base to PRPP and produces a __________?

A

nucleotide monophosphate

24
Q

what happens if there was an enzyme deficiency in the purine salvage pathway?

A

brain would be overwhelmed with de novo synthesis and couldn’t utilize the pathway

Lesch-Nyhan syndrome

25
Q

further breakdown of purines requires

A

xanthine oxidase

26
Q

what is the enzyme that is oxidized to produce uric acid?

A

xanthine oxidase

27
Q

free bases converted into common bases =

A

xanthine

28
Q

what is the final metabolic product of purine catabolism?

A

uric acid

29
Q

what inhibits xanthine oxidase?

A

allopurinal

30
Q

which synthetic drug is an inhibitor of purine synthesis?

A

methotrexate- also inhibits tetrahydrofolate

cancer, rheumatoid arthritis and psoriasis treatment

31
Q

what is the location of pyrimidine de novo synthesis?

A

spleen
thymus
GI tract
testes

32
Q

what is the regulatory step of pyrimidine synthesis?

A

carbamoyl phosphate

33
Q

what inhibits and stimulates carbamoyl phosphate

A

inhibited by UTP

stimulated by PRPP

34
Q

what is the enzyme needed in the regulatory step of pyrimidine synthesis?

A

carbamoyl phosphate synthetase

35
Q

what forms the ring in pyrimidine synthesis?

A

CAD

36
Q

what does CAD stand for?

A

Carbamoyl phosphate synthetase
Aspartate transcarbamyolase
Dihydrorotase

37
Q

what is CTP synthesized from?

A

uracil - UMP first is phosphorylated to UDP, then UTP

38
Q

what enzyme is needed for amination of UTP to form CTP?

A

CTP synthetase

39
Q

what 2 amino acids are needed for the formation of CTP from UTP?

A

glutamate

glutamine

40
Q

TMP is unique to DNA and needs which enzyme?

A

ribonucleotide reductase

41
Q

what enzyme catalyses the formation of deoxyribonucleotides?

A

ribonucleotide reductase

42
Q

what enzyme is needed for thymidine synthesis?

A

thymidylate synthase- NADPH is also required

43
Q

what does the pyrimidine salvage pathway break down?

A

not as significant as purine;

nitrogen transferred to form AAs (glutamate)
what is left can be converted into FA synthesis or krebs intermediates

44
Q

what enzymes are required for pyrimidine salvage pathway?

A

nucleoside phosphorylase

nucleoside kinase

45
Q

the pyrimidine salvage pathway is the primary pathway for?

A

uracil and thymine

46
Q

what 3 amino acids donate nitrogen?

A

aspartate
glutamate
glutamine

47
Q

what are the 3 donors of carbon?

A

bicarbonate
CO2
THF

biochem 2 final (5 decks)

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