Moizy 1 Flashcards

0
Q

T or F. In purine synthesis, donated atoms are added to a preformed ribose 5 phosphate.

A

True.

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1
Q

Atoms of a purine ring are donated by which 3 amino acids?

A

aspartic acid, glutamine, glycine.

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2
Q

Ribose 5 phosphate to PRPP.

A

PRPP synthetase

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3
Q

PRPP synthetase is inhibited by

A

free floating phosphate

purines (end product inhibition)

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4
Q

What is the committed step of purine synthesis?

A

PRPP to 5’ phosphoribosylamine.

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5
Q

5’ phosphoribosylamine to inosine 5 monophosphate (IMP) costs how much ATP?

A

4

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6
Q

What do sulfonamides do?

A

Block IMP production by inhibiting folic acid synthesis. No folic acid, no tetrahydrofolate (THF) cofactor for purine synthesis.

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7
Q

T or F. Because sulfonamides inhibit folic acid synthesis, humans are affected by sulfonamides.

A

False. Humans cannot synthesize folic acid.

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8
Q

What does methotrexate do?

A

Analog of folic acid, decreases reduction of dihydrofolate (DHF) to THF.

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9
Q

Synthesis of IMP to AMP requires _____.

Synthesis of IMP to GMP requires ______.

A

GTP

ATP.

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10
Q

IMP to GMP. enzyme?

A

IMP dehydrogenase.

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11
Q

What does mycophenolic acid (MPA) do?

A

blocks IMP dehydrogenase, blocks GMP production depriving rapidly proliferating T and B cells of nucleic acids, decreasing graft rejection.

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12
Q

AMP to ADP

GMP to GDP

A

base specific nucleoside monophosphate kinases.
adenylate kinase
guanylate kinase

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13
Q

T or F. Nucleoside diphosphate kinases are base specific, similar to nucleoside monophosphate kinases.

A

False. Broad specificity.

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14
Q

Pyrimidines are made ______ being attached to ribose 5 phosphate.

A

before

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15
Q

Which amino acids donate atoms to pyrimidines?

A

aspartic acid, glutamine (no glycine like purines).

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16
Q

In pyrimidine synthesis, Glutamine –> ___________ using what enzyme? Is ATP used or produced, and how many?

A

carbomoyl phosphate using carbomoyl phosphate synthetase.

2 ATP used.

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17
Q

T or F. Glutamine to carbamoyl phosphate is the regulated step in mammals.

A

True.

18
Q

Carbomyl phosphate to carbomyl aspartate to dihydroorotate.

A

aspartate transcarbamoylase, dihydroorotase (part of a 3 subunit enzyme with carbomoyl phosphate synthetase).

19
Q

Orotate to orotidine 5 monophosphate to uridine 5 monophosphate (UMP).

A

orotate phosphoribosyl transferase, dmp decarboxylase. two subunits of the same enzyme.

20
Q

orolate to OMP requires ______.

A

PRPP.

21
Q

Orotic aciduria is a defect in ___________ and _____________ resulting in __________.

A

orotate phosphoribosyl transferase and OMP decarboxylase, results in high orotate in urine.

22
Q

What can help orotic aciduria?

A

rich uridine diet.

23
Q

UTP to CTP requires

A

glutamine (becomes glutamate)

ATP (becomes ADP)

24
Q

Deoxyribonucleoside diphosphate (dNDP) can be made using _______ (precursor) and ________ (enzyme).

A

ribonucleoside diphosphate

ribonucleotide reductase.

25
Q

What can allosterically inhibit ribonucleotide reductase? What is the consequence of this?

A

dATP. prevents DNA synthesis. Such as in adenosine deaminase deficiency.

26
Q

dUMP to dTMP. What enzyme. What else is needed in the reaction?

A

thymidylate synthetase. Requires THF, which turns into DHF.

27
Q

What can inhibit thymidylate synthetase?

A

5 fluorouracil “suicide inhibitor”

28
Q

Decreased THF can result which of the following?
inhibition of purine synthesis
inhibition of dTMP production.

A

Both.

29
Q

Degradation of dietary nucleic acids occurs in the __________

A

small intestine.

30
Q

Purine nucleotides are degraded into _____.

A

Uric acid.

31
Q

What is gout?

A

high levels of uric acid in the blood, resulting in needle shaped crystals in tissues.

32
Q

What is a treatment of gout?

A

Allopurinol. Accumulates the water soluble hypoxanthine and xanthine, the immediate precursors to uric acid.

33
Q

Adenosine deaminase deficiency in lymphocytes results in

A

SCID. T and B cells can’t replicate.

34
Q

Pyrimidines can be degraded into _______ or _______, which are precursors to ______ and _______.

A

beta alanine, beta aminoisobutyrate

precursors: ACoA, Succinyl CoA.

35
Q

Purines can be reconverted into nucleotides using _____and ____ enzymes. Both use _____ as source of ribose 5 phosphate.

A

APRT, HPRT.

PRPP

36
Q

What is lesch nyhan syndrome?

A

Complete deficiency of HPRT. hypoxanthine and guanine cant be reconverted, becomes uric acid. Since HPRT deficient, PRPP increases, causes purine synthesis, but no way to degrade purine. Uric acid.
Gout, kidney stones, neuro symptoms, self mutilation

37
Q

Amino acids can derive catecholamines. Name 3 catecholamines.

A

Epinephrine, Norepinephrine, Dopamine.

38
Q

Catecholamines are synthesized from _______

A

Tyrosine.

39
Q

Catecholamines are inactivated by oxidative deamination by MAO. ____________ inactivate MAO, which _______ the level of catecholamines (antidepressant)

A

MAO inhibitors

increases

40
Q

______ given to Parkinson’s patients to stimulate dopamine synthesis.

A

L dopa

41
Q

_______is the amino acid precursor to seratonin.

A

Tryptophan.

42
Q

How does paxil and prozac work?

A

Low levels of seratonin linked to depression. Paxil and Prozac block seratonin transporters, increasing synaptic seratonin.