Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Biochemistry > Purine and Pyrimidine Formation > Flashcards

Purine and Pyrimidine Formation Flashcards

1
Q

What are the sources of pyrimidine?

A

HCO3, Gln, Asp, N-10 form of THF

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are dietary pyrimidines converted into?

A

malonyl CoA, methyl malonyl CoA and succinyl CoA.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is the committed step in the synthesis of purines?

A

The formation of phosphoribosyl amine (PRA). It is the second step of the cycle.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What enzyme converts PPRP to PRA (e.g. the committed step)?

A

glutamine:phosphororibosyl pyrophosphate.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What inhibits and activates glutamine:phosphorylribosyl pyrophosphate?

A

PRPP activates, purines inhibit

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What amino acid is used in the committed step (PRPP to PRA)?

A

Glutamine. It is converted into glycine.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is ionisine monophosphate (IMP) converted into?

A

Adenylosuccinate monophosphate or xanthine mp

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is de novo synthesis?

A

The synthesis of purines and pyrimidines from other compounds.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

After pyrimidines are asssembled, what are they attached to?

A

ribose

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What are purines attached to during synthesis?

A

ribose

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is the first molecule in the purine de novo synthesis pathway?

A

alpha D ribose-5-phosphate.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What enzyme converts alpha-D-ribose phosphate into PRPP?

A

PRPP synthetase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What inhibits and activtes PRPP synthetase?

A

phosphate activates and purine nucleotides inhibit.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What compound inhibits the PRA from forming IMP?

A

methotrexate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What molecules are used in the nine step conversion of PRA to IMP?

A

CO2, Gln, Asp, Gly, and N10 THF

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What enzyme converts IMP into AMP?

A

Adenylosuccinate synthetase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is adenylosuccinate synthetase inhibited by?

A

AMP

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What enzyme converts adenylosuccinate monophosphate into adenosine monophosphate (AMP)?

A

adenylosuccinase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What enzyme converts ADP/GDP into dADP/dGDP?

A

adenylosuccinase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is PRPP synthesized from?

A

Ribose and ATP.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What enzyme converts IMP into XMP?

A

IMP dehydrogenase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What does THF do in the nine stemp reaction of PRA to IMP?

A

Closes the purine ring that is synthesized.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is methotrexate used for?

A

Kidney cancer; it prevents cells from replicating DNA.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

The reaction of adenylosuccinate monophosphate to AMP results in the formation of what molecule that enters TCA?

A

fumarate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What do AMP and GMP inhibit?

A

The enzymes (adenylosuccinate monophosphate synthetase and IMP dehydrogenase) that covert IMP into AMP & GMP.

26
Q

What is AMP/GMP synthesis stimulated by?

A

ATP and GTP

27
Q

UMP and UDP kinases allow for the conversion of UMP/UDP into what molecules?

A

UDP and UTP

28
Q

What is pyrimidine synthesized from?

A

carbamoyl phosphate and aspartate; aspartate carbamoylase facilitates the reaction.

29
Q

What is the first molecule in the pyrimidine synthesis pathway?

A

glutamine

30
Q

In pyrimidine synthesis, what is glutamine converted into?

A

carbamoyl phosphate

31
Q

In pyrimidine synthesis, what enzyme converts glutamine into carbamoyl phosphate?

A

carbamoyl phosphate synthetase II

32
Q

What amino acid is created upon the synthesis of glutamine to carbamoyl phosphate?

A

Glutamate; a molecule of ATP is also used.

33
Q

The conversion of carbamoyl phosphate to carbamoyl aspartate occurs when what enzyme is present?

A

aspartate transcarbamoylase

34
Q

What molecule is carbamoyl phosphate converted into?

A

carbamoyl aspartate

35
Q

Carbamoyl aspartate is converted into what molecule?

A

dihydro-orotate

36
Q

What enzyme converts carbamoyl aspartate into dihydro ortate?

A

dihydro orotase

37
Q

What is dihydro orotate converted into?

A

orotate

38
Q

Where do the first three steps of pyrimidine synthesis occur?

A

in the mitochondria

39
Q

What enzyme converts dihydro orotate into orotate?

A

dihydro orotate dehydrogenase

40
Q

What is orotate converted into?

A

OMP

41
Q

What enzyme converts orotate into OMP?

A

UMP synthase

42
Q

What enzyme converts OMP into UMP?

A

UMP synthase

43
Q

UMP is converted into what molecule?

A

UDP

44
Q

UDP can be converted into what two molecules?

A

UTP or dUTP

45
Q

UDP is converted into dUDP by what enzyme?

A

ribonucleotide reductase

46
Q

UTP is converted into CTP by what enzyme?

A

CTP synthase

47
Q

CTP is converted into dCTP by what enzyme?

A

ribonucleotide reductase

48
Q

dUMP is converted into dUTP by what enzyme?

A

thymidliate synthase

49
Q

Thymidiliate synthase is inhibited by what molecule?

A

5-fluorouracil

50
Q

What is the committed step of pyridine synthesis?

A

The conversion of carbamoyl phosphate into carbamoyl aspartate.

51
Q

What is orotic aciduria, and what enzyme in the pyrimidine synthesis pathway is it associated with?

A

The inability to synthesize pyrimidines, and hence DNA. It is associated with UMP synthase.

52
Q

What are deoxyribonucleotides formed from?

A

ribonucleotides

53
Q

What enzyme reduces ribonucleotides (and makes deoxyribonucleotides)?

A

ribonucleotide reductase

54
Q

What enzyme is inhibited by CTP and activated by AMP?

A

ATCase

55
Q

DNA is synthesized from what four molecules?

A

dATP, dGTP, dCTP and dTTP

56
Q

What is the salvage pathway?

A

A pathway that builds nucleotides from free bases.

57
Q

What enzyme in the purine salvage pathway converts an adenine base into AMP?

A

adenosine phosphoribyl transferase (APRT)

58
Q

What enzyme in the purine salvage pathway converts a guanine base into GMP?

A

HGPRT

59
Q

What are the sources of purine?

A

CO2, Gln, Gly, Asp, N-10 form of THF

60
Q

Which nucleotide is the limiting factor in DNA synthesis?

A

dTTP

Biochemistry (6 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions