Moizy 1

Question 0

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

Answer 0

True.

Question 1

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

Answer 1

aspartic acid, glutamine, glycine.

Question 2

Ribose 5 phosphate to PRPP.

Answer 2

PRPP synthetase

Question 3

PRPP synthetase is inhibited by

Answer 3

free floating phosphate

purines (end product inhibition)

Question 4

What is the committed step of purine synthesis?

Answer 4

PRPP to 5’ phosphoribosylamine.

Question 5

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

Answer 5

4

Question 6

What do sulfonamides do?

Answer 6

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

Question 7

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

Answer 7

False. Humans cannot synthesize folic acid.

Question 8

What does methotrexate do?

Answer 8

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

Question 9

Synthesis of IMP to AMP requires _____.

Synthesis of IMP to GMP requires ______.

Answer 9

GTP

ATP.

Question 10

IMP to GMP. enzyme?

Answer 10

IMP dehydrogenase.

Question 11

What does mycophenolic acid (MPA) do?

Answer 11

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

Question 12

AMP to ADP

GMP to GDP

Answer 12

base specific nucleoside monophosphate kinases.
adenylate kinase
guanylate kinase

Question 13

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

Answer 13

False. Broad specificity.

Question 14

Pyrimidines are made ______ being attached to ribose 5 phosphate.

Answer 14

before

Question 15

Which amino acids donate atoms to pyrimidines?

Answer 15

aspartic acid, glutamine (no glycine like purines).

Question 16

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

Answer 16

carbomoyl phosphate using carbomoyl phosphate synthetase.

2 ATP used.

Question 17

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

Answer 17

True.

Question 18

Carbomyl phosphate to carbomyl aspartate to dihydroorotate.

Answer 18

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

Question 19

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

Answer 19

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

Question 20

orolate to OMP requires ______.

Answer 20

PRPP.

Question 21

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

Answer 21

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

Question 22

What can help orotic aciduria?

Answer 22

rich uridine diet.

Question 23

UTP to CTP requires

Answer 23

glutamine (becomes glutamate)

ATP (becomes ADP)

Question 24

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

Answer 24

ribonucleoside diphosphate

ribonucleotide reductase.

Question 25

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

Answer 25

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

Question 26

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

Answer 26

thymidylate synthetase. Requires THF, which turns into DHF.

Question 27

What can inhibit thymidylate synthetase?

Answer 27

5 fluorouracil “suicide inhibitor”

Question 28

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

Answer 28

Both.

Question 29

Degradation of dietary nucleic acids occurs in the __________

Answer 29

small intestine.

Question 30

Purine nucleotides are degraded into _____.

Answer 30

Uric acid.

Question 31

What is gout?

Answer 31

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

Question 32

What is a treatment of gout?

Answer 32

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

Question 33

Adenosine deaminase deficiency in lymphocytes results in

Answer 33

SCID. T and B cells can’t replicate.

Question 34

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

Answer 34

beta alanine, beta aminoisobutyrate

precursors: ACoA, Succinyl CoA.

Question 35

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

Answer 35

APRT, HPRT.

PRPP

Question 36

What is lesch nyhan syndrome?

Answer 36

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

Question 37

Amino acids can derive catecholamines. Name 3 catecholamines.

Answer 37

Epinephrine, Norepinephrine, Dopamine.

Question 38

Catecholamines are synthesized from _______

Answer 38

Tyrosine.

Question 39

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

Answer 39

MAO inhibitors

increases

Question 40

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

Answer 40

L dopa

Question 41

_______is the amino acid precursor to seratonin.

Answer 41

Tryptophan.

Question 42

How does paxil and prozac work?

Answer 42

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