Nucleotides

Question 1

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

Answer 1

Nucleoside

Question 2

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

Answer 2

Pentose

Question 3

Polynucleotides are written in what direction

Answer 3

5’ to 3’

Question 4

Rate limitjng enzyme of purine synthesis

Answer 4

PRPP glutamyl amidotransferase

Question 5

Rate limiting enzyme of pyrimidine synthesis

Answer 5

Carbamoyl phosohate II

Question 6

Donors of atoms in purine synthesis

Answer 6

GAC GN

Glutamine
Aspartate
Carbon dioxide

Glycine
N10-formyltetrahydrofolate

Question 7

Donors of atoms in pyrimidine synthesis

Answer 7

GAC

Glutamine
Aspartate
Carbon dioxide

Question 8

Sequence of steps in purine synthesis

Answer 8

Ribose 5P —-> purine ring construction

Question 9

Sequence of steps in pyrimidine synthesis

Answer 9

Pyrimidine ring formation —-> attachment to ribose 5phosphate

Question 10

Parent molecule purine synthesis

Answer 10

Inosine monophosphate

Question 11

Parent molecule pyrimidine synthesis

Answer 11

Orotidine monophosphate

Question 12

Products of of purine synthesis (2)

Answer 12

GMP (requires ATP)

AMP (requires GTP)

Question 13

Products of PYR synthesis (2)

Answer 13

CTP, TMP, UDP

UMP—> UTP —> CTP

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

Question 14

Enzyme that activates r5p

Answer 14

PRPP syntetase

R5P—>5-PRPP

Question 15

Energy requirement for prpp reaction

Answer 15

ATP to AMP

Question 16

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

Answer 16

PRPP

Question 17

Inhibits PRPP synthetase

Answer 17

ADP

Question 18

Inhibits PRPP —-> 5 phosphoribosylamine

Enzyme glutamine PRPP amidotransferase

Answer 18

AMP IMP

GMP

Question 19

Pyrimidine synthesis

Multisubunit enzyme that reduces nucleoside diphosohates to their deoxy forms

Answer 19

Ribinucleotide reductase

Question 20

Ribinucleotide reductase facilitate redox reactions that require ____ and ____

Answer 20

Thioredoxin

NADPH

Question 21

Pyr synthesis

Enzyme that converts dUMP to thymine

Answer 21

Thymidilate synthase

Question 22

Cofactor for thymidilate synthase in pyr synthesis

Answer 22

N5, N10 methylene tetrahydrofolate

Inhibited by 5-fluorouracil

Question 23

Purine/pyrimidine

Ring cannot be cleaved in human cells

Answer 23

Purine

Question 24

Purine/pyrimidine

Ring can be opened and degraded ro water soluble products

Answer 24

Pyr

Question 25

Product of purine degradatiom

Answer 25

Uric acid

Question 26

Product of pyr degradation (2)

Answer 26

Beta alanine (precursor for acetyl CoA) Beta aminoisobutyrate (precursor for succinyl CoA)

Question 27

Disease associated with accumulation of purine, pyrimidine

Answer 27

Gout | Orotic aciduria, respectively

Question 28

Conversion of purines, ribonucleotides, and their deoxyribonucleotides to mononucleotides

Answer 28

Salvage purine pathway

Question 29

Requires LESSenergy than de novo synthesis

Answer 29

Salvage pathway

Question 30

2 irreversible enzymes in salvage pathway of purine

Answer 30

APRT and HGPRT Adenine phosphoribosyltransferase Hypoxanthine guanine phosphoribosyltransferase

Question 31

Source of ribose 5 phosphate in purine salvage pathway

Answer 31

PRPP

Question 32

Drugs that inhibit nucleotide metabolism | Inhibits xanthine oxidase

Answer 32

Allopurinol

Question 33

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

Answer 33

Sulfonamides

Question 34

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

Answer 34

Trimethoprim

Question 35

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

Answer 35

5 FU

Question 36

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

Answer 36

Methotrexate

Question 37

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

Answer 37

Mycophenolate

Question 38

Enzyme deficiency | Lesch nyhan

Answer 38

HGPRT (inc PRPP and uric acid)

Question 39

Enzyme deficiency | SCID

Answer 39

Adenosince deaminase | Inc dATP inhibits ribonucleotide synthase

Question 40

Enzyme deficiency | Von Gierke

Answer 40

Glucose 6 phosphatase | Inc ribose 5 phosphate

Question 41

Enzyme deficiency | Orotic aciduria

Answer 41

Orotidine phosphate decarboxylase or | Orotate phosphoribosyl transferase

Question 42

Enzyme deficiency | Beta hydroxybutyric aciduria

Answer 42

Dihydropyridine dehydrigenase

Question 43

X linked | Gout, self-mutilation, mental retardation

Answer 43

Lesch nyhan

Question 44

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

Answer 44

SCID

Question 45

Purine overproduction and hyperuricemia

Answer 45

Von Gierke

Question 46

Poor growth Megaloblastic anemia Orotate in urine Treat with uridine

Answer 46

Orotic aciduria

Question 47

Combined uraciluria-thyminuria | Impaired formation of beta alanine and of bet aminoisobutyrate

Answer 47

Beta hydroxybutyric aciduria