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Biol214 > Nucleotides- De novo pathway > Flashcards

Nucleotides- De novo pathway Flashcards

1
Q

metabolic precursors:

A

ribose-5-phosphate, amino acids,
CO2 and NH3

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2
Q

are de novo pathways of nucleotide synthesis energetically expensive?

A

yes

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3
Q

glycine is the precursor for purines or pyramidines?

A

purines

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4
Q

aspartate is the precursor for purines or pyramidines?

A

pyramidines

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5
Q

what are the two pathways of nucleotide synthesis?

A

de novo pathway and salvage pathways

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6
Q

salvage pathway is when: free bases and nucleosides released from nucleic acid breakdown are ???

A

recycled

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7
Q

PRPP (5-phosphoribosyl 1-pyrophosphate) is what the purine or pyramidine ring is assembled on?

A

purine ring

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8
Q

in the first committed step of purine pathway, an amino acid is donated by ??? and attached to C-1 of PRPP ring

A

glutamine

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9
Q

what is formed through the donation of an amino acid by glutamine to PRPP in comitment step 1 of purine synthesis?

A

5-phosphoribosylamine

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10
Q

in the 2nd step of purine synthesis, 3 atoms are donated from ??? ATP is required for this step

A

glycine

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11
Q

in higher eukaryotes, 10 steps are required in purine synthesis to form the ring structure and the nucleotide ???

A

inosinate (IMP)

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12
Q

TRUE or FALSE: in purine synthesis, IMP is the first intermediate with a
complete purine ring

A

TRUE

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13
Q

TRUE or FALSE: Inosinate forms a branch point in purine de novo pathway: can form adenylate (AMP) or Guanylate (GMP)

A

TRUE

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14
Q

Conversion of IMP to Adenylate (AMP) requires an amino group from ???, requiring GTP

A

aspartate

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15
Q

Conversion of IMP to GMP requires an amino group from ???, requiring ATP

A

glutamine

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16
Q

the amount and availability of AMP, GMP, and IMP can inhibit the conversion of ??? to 5-phosphoribosylamine

A

PRPP

17
Q

AMP amounts can inhibit conversion of IMP to ???

A

AMP

18
Q

GMP amounts can inhibit conversion of IMP to ???

A

GMP

19
Q

the amount and availability of ATP can inhibit the conversion of ribose-5-phosphate to ???

A

PRPP

20
Q

Pyrimidine synthesis proceeds by first making the pyrimidine ring in the form of ???

A

orotate

21
Q

??? and carbamoyl phosphate provide the atoms for the ring structure, making synthesis of pyrimidine ring simpler than purine ring

A

Aspartate

22
Q

Ribose 5-phosphate is attached BEFORE or AFTER pyrimidine ring formation

A

AFTER

23
Q

Ribonucleotide reductase converts ??? to deoxyribonucleotides

A

ribonucleotides

24
Q

Thioredoxin acts as an ??? protein that carries a pair of H atoms, via –SH groups, from NADPH to the ribonucleoside diphosphate

A

intermediate hydrogen-carrying

25
Q

Thioredoxin reductase catalyses the reduction of the ??? form of thioredoxin by NADPH

A

oxidised

26
Q

Reduction of Ribonucleotides to Deoxyribonucleotides: Electrons and H+ are transmitted from ??? to ??? via
glutaredoxin and thioredoxin

A

NADPH to ribonucleotide reductase

27
Q

Reduction of ribonucleotides to deoxyribonucleotides: Glutaredoxin transfers electrons from ??? to ribonucleotide reductase

A

glutathione (GSH)

28
Q

Reduction of Ribonucleotides to deoxyribonucleotides: Thioredoxin transfers pair of H+ to ??? required to form dNDP

A

ribonucleotide reductase

29
Q

ribonucleotide reductase is regulated by the binding of ??? also Deoxynucleoside Triphosphates

A

effector molecules

30
Q

Regulation of Ribonucleotide Reductase: dATP, dGTP, dTTP, dCTP inhibited by Deoxynucleoside Triphosphate –> dATP at primary or secondary regulation sites?

A

primary

31
Q

TRUE or FALSE: regulation at primary sites helps regulate overall production

A

TRUE

32
Q

dTTP is an inhibitor of dUDP and dCDP as well as an activator of dGDP for the regulation of ??? at substrate specific specific sites

A

ribonucleotide reductase

33
Q

dGTP is an inhibitor of dUDP and dCDP and dGDP as well as an activator of dADP for the regulation of ??? at substrate specific sites

A

ribonucleotide reductase

34
Q

dTMP (Thymidylate) is derived from dCDP and dUMP. ??? catalyses the conversion of dUMP to dTMP

A

Thymidylate synthase

35
Q

TRUE or FALSE: Folic acid deficiency results in excess incorporation of uracil into DNA leading to DNA damage causing neural tube defects

A

true

Biol214 (12 decks)

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