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Biochemistry by mgcMD > Nucleotides > Flashcards

Nucleotides Flashcards

1
Q

Contains D ribose or 2 deoxy D ribose
Linked ro N1 of a pyrimidine
Or N-9 of purine
By B-N-glycosidic bond

A

Nucleoside

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2
Q

In nucleotides, the phosphoryl group is usually attached to C-5 of the

A

Pentose

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3
Q

Polynucleotides are written in what direction

A

5’ to 3’

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4
Q

Rate limitjng enzyme of purine synthesis

A

PRPP glutamyl amidotransferase

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5
Q

Rate limiting enzyme of pyrimidine synthesis

A

Carbamoyl phosohate II

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6
Q

Donors of atoms in purine synthesis

A

GAC GN

Glutamine
Aspartate
Carbon dioxide

Glycine
N10-formyltetrahydrofolate

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7
Q

Donors of atoms in pyrimidine synthesis

A

GAC

Glutamine
Aspartate
Carbon dioxide

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8
Q

Sequence of steps in purine synthesis

A

Ribose 5P —-> purine ring construction

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9
Q

Sequence of steps in pyrimidine synthesis

A

Pyrimidine ring formation —-> attachment to ribose 5phosphate

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10
Q

Parent molecule purine synthesis

A

Inosine monophosphate

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11
Q

Parent molecule pyrimidine synthesis

A

Orotidine monophosphate

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12
Q

Products of of purine synthesis (2)

A

GMP (requires ATP)

AMP (requires GTP)

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13
Q

Products of PYR synthesis (2)

A

CTP, TMP, UDP

UMP—> UTP —> CTP

UMP —-ribonucleotide reductase —> dUMP
dUMP—-thymidylate synthase—> TMP

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14
Q

Enzyme that activates r5p

A

PRPP syntetase

R5P—>5-PRPP

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15
Q

Energy requirement for prpp reaction

A

ATP to AMP

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16
Q

Donor of R5P of nucleotides, whether synthesized de novo or through salvage pathways

A

PRPP

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17
Q

Inhibits PRPP synthetase

A

ADP

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18
Q

Inhibits PRPP —-> 5 phosphoribosylamine

Enzyme glutamine PRPP amidotransferase

A

AMP IMP

GMP

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19
Q

Pyrimidine synthesis

Multisubunit enzyme that reduces nucleoside diphosohates to their deoxy forms

A

Ribinucleotide reductase

20
Q

Ribinucleotide reductase facilitate redox reactions that require ____ and ____

A

Thioredoxin

NADPH

21
Q

Pyr synthesis

Enzyme that converts dUMP to thymine

A

Thymidilate synthase

22
Q

Cofactor for thymidilate synthase in pyr synthesis

A

N5, N10 methylene tetrahydrofolate

Inhibited by 5-fluorouracil

23
Q

Purine/pyrimidine

Ring cannot be cleaved in human cells

A

Purine

24
Q

Purine/pyrimidine

Ring can be opened and degraded ro water soluble products

A

Pyr

25
Q

Product of purine degradatiom

A

Uric acid

26
Q

Product of pyr degradation (2)

A

Beta alanine (precursor for acetyl CoA)

Beta aminoisobutyrate (precursor for succinyl CoA)

27
Q

Disease associated with accumulation of purine, pyrimidine

A

Gout

Orotic aciduria, respectively

28
Q

Conversion of purines, ribonucleotides, and their deoxyribonucleotides to mononucleotides

A

Salvage purine pathway

29
Q

Requires LESSenergy than de novo synthesis

A

Salvage pathway

30
Q

2 irreversible enzymes in salvage pathway of purine

A

APRT and HGPRT

Adenine phosphoribosyltransferase
Hypoxanthine guanine phosphoribosyltransferase

31
Q

Source of ribose 5 phosphate in purine salvage pathway

A

PRPP

32
Q

Drugs that inhibit nucleotide metabolism

Inhibits xanthine oxidase

A

Allopurinol

33
Q

Drugs that inhibit nucleotide metabolism
Structural analog of PABA
Competitively inhibits dihydripteroate synthase
(Conversion of PABA to folate)

A

Sulfonamides

34
Q

Drugs that inhibit nucleotide metabolism
Stuctural analog of folate
Slectively inhibits bacterial dihydrofolate reductase
(Conversion of THF from folate)

A

Trimethoprim

35
Q

Drugs that inhibit nucleotide metabolism
Metbolically converted to 5 FdUMP which inhibits thymidilate synthase
(DTMP to dUMP)

A

5 FU

36
Q

Inhibits dihydrofolate reductase which reduces the tetrahydrofolate supply for the synthesis of thymine

A

Methotrexate

37
Q

Drugs that inhibit nucleotide metabolism
Reversible inhibitor of IMP dehydrogenase
Depriving T and B lymphocytes of nucleic acids
(Fglu rxns)

A

Mycophenolate

38
Q

Enzyme deficiency

Lesch nyhan

A

HGPRT (inc PRPP and uric acid)

39
Q

Enzyme deficiency

SCID

A

Adenosince deaminase

Inc dATP inhibits ribonucleotide synthase

40
Q

Enzyme deficiency

Von Gierke

A

Glucose 6 phosphatase

Inc ribose 5 phosphate

41
Q

Enzyme deficiency

Orotic aciduria

A

Orotidine phosphate decarboxylase or

Orotate phosphoribosyl transferase

42
Q

Enzyme deficiency

Beta hydroxybutyric aciduria

A

Dihydropyridine dehydrigenase

43
Q

X linked

Gout, self-mutilation, mental retardation

A

Lesch nyhan

44
Q

Lymphocytipenia
Death before age because of overwhelming infection
Treat with BM transplant
Gene therapy

A

SCID

45
Q

Purine overproduction and hyperuricemia

A

Von Gierke

46
Q

Poor growth
Megaloblastic anemia
Orotate in urine
Treat with uridine

A

Orotic aciduria

47
Q

Combined uraciluria-thyminuria

Impaired formation of beta alanine and of bet aminoisobutyrate

A

Beta hydroxybutyric aciduria

Biochemistry by mgcMD (19 decks)

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