Deck 32: Nucleotide Metabolism

Question 1

Use the following to answer questions
Choose the correct answer from the list below. Not all of the answers will be used.
a) de novo
b) xanthylate
c) riboflavin
d) amino acids
e) UTP
f) N5, N10-methylenetetrahydrofolate
g) nucleotide
h) gout
i) nucleoside
j) ATP
k) urate
l) salvage
A purine or pyrimidine base linked to a sugar is a(n) _________________.

Answer 1

i

Question 2

Use the following to answer questions
Choose the correct answer from the list below. Not all of the answers will be used.
a) de novo
b) xanthylate
c) riboflavin
d) amino acids
e) UTP
f) N5, N10-methylenetetrahydrofolate
g) nucleotide
h) gout
i) nucleoside
j) ATP
k) urate
l) salvage
The final product of purine degradation is _________________.

Answer 2

k

Question 3

The committed step in purine nucleotide biosynthesis is the conversion of __________________ to 5-phosphoribosyl-1-amine.

Answer 3

PRPP

Question 4

Use the following to answer questions
Choose the correct answer from the list below. Not all of the answers will be used.
a) de novo
b) xanthylate
c) riboflavin
d) amino acids
e) UTP
f) N5, N10-methylenetetrahydrofolate
g) nucleotide
h) gout
i) nucleoside
j) ATP
k) urate
l) salvage
Assembly of a compound from phophoribosylpyrophosphate (PRPP) and a base is known as a(n) _________________ pathway.

Question 5

Use the following to answer questions
Choose the correct answer from the list below. Not all of the answers will be used.
a) de novo
b) xanthylate
c) riboflavin
d) amino acids
e) UTP
f) N5, N10-methylenetetrahydrofolate
g) nucleotide
h) gout
i) nucleoside
j) ATP
k) urate
l) salvage
The intermediate between inosinate and guanylate is _________________.

Question 6

Hypoxanthine-guanine phosphoribosyltransferase catalyzes the formation of guanylate and __________________.

Question 7

Use the following to answer questions
Choose the correct answer from the list below. Not all of the answers will be used.
a) de novo
b) xanthylate
c) riboflavin
d) amino acids
e) UTP
f) N5, N10-methylenetetrahydrofolate
g) nucleotide
h) gout
i) nucleoside
j) ATP
k) urate
l) salvage
A purine or pyrimidine base linked to a sugar and to a phosphate ester is a(n) _________________.

Question 8

Use the following to answer questions
Choose the correct answer from the list below. Not all of the answers will be used.
a) de novo
b) xanthylate
c) riboflavin
d) amino acids
e) UTP
f) N5, N10-methylenetetrahydrofolate
g) nucleotide
h) gout
i) nucleoside
j) ATP
k) urate
l) salvage
High levels of urate cause the disease _________________.

Question 9

Fluorouracil acts as an analog of __________________.

Question 10

In __________________ biosynthesis, the base is assembled first and then attached to ribose.

Question 11

Use the following to answer questions
Choose the correct answer from the list below. Not all of the answers will be used.
a) de novo
b) xanthylate
c) riboflavin
d) amino acids
e) UTP
f) N5, N10-methylenetetrahydrofolate
g) nucleotide
h) gout
i) nucleoside
j) ATP
k) urate
l) salvage
Assembly of a compound from simpler molecules is known as a(n) _______________ pathway.

Question 12

The conversion of ribonucleotides to deoxyribonucleotides is catalyzed by ________________.

Question 13

__________________ disease is caused by a genetic mutation resulting in the absence of hypoxanthine-guanine phosphoribosyltransferase.

Question 14

DNA is built from __________________.

Question 15

Use the following to answer questions
Choose the correct answer from the list below. Not all of the answers will be used.
a) de novo
b) xanthylate
c) riboflavin
d) amino acids
e) UTP
f) N5, N10-methylenetetrahydrofolate
g) nucleotide
h) gout
i) nucleoside
j) ATP
k) urate
l) salvage
The methyl donor to make TMP is _________________.

Question 16

Scaffolds for the ring systems in nucleotides are from the amino acids glycine and __________________.

Question 17

Dihydrofolate reductase is an excellent target for anticancer drugs because it is critical in the synthesis of __________________.

Question 18

Some individuals with a deficiency in the enzyme adenosine deaminase exhibit __________________.

Question 19

Use the following to answer questions
Choose the correct answer from the list below. Not all of the answers will be used.
a) de novo
b) xanthylate
c) riboflavin
d) amino acids
e) UTP
f) N5, N10-methylenetetrahydrofolate
g) nucleotide
h) gout
i) nucleoside
j) ATP
k) urate
l) salvage
Purines and pyrimidines are derived from _________________.

Question 20

Use the following to answer questions
Choose the correct answer from the list below. Not all of the answers will be used.
a) de novo
b) xanthylate
c) riboflavin
d) amino acids
e) UTP
f) N5, N10-methylenetetrahydrofolate
g) nucleotide
h) gout
i) nucleoside
j) ATP
k) urate
l) salvage
CTP is formed by the amination of _________________.

Question 21

How many ATP molecules are necessary to make carbamoyl phosphate by carbamoyl phosphate synthetase (CPS)?

A) 1
B) 4
C) 2
D) 3
E) None of the above.

Question 22

In de novo synthesis, the pyrimidine ring is assembled using:

A) bicarbonate.
B) aspartate.
C) glutamine.
D) A and B.
E) A, B, and C.

Question 23

Inosinate can be converted to:

A) AMP.
B) GMP.
C) UMP.
D) A or B.
E) A, B, or C.

Question 24

Given the function of nucleotides, would you expect their synthesis to be simple or complex and diverse?

Question 25

What reaction actually forms the six-member ring found in pyrimidines?

Question 26

Describe the reaction by which carbamoyl phosphate synthetase acquires an ammonia to make carbamoyl phosphate.

Question 27

Which enzyme carries out this reaction: XDP + YTP ↔ XTP + YDP

A) nucleoside triphosphate kinase
B) nucleoside diphosphate kinase
C) nucleoside diphosphate phosphorylase
D) nucleoside triphosphate phosphorylase
E) None of the above.

Question 28

Tetrahydrofolate is generated from dihydrofolate by dihydrofolate reductase and uses the reductant:

A) FADH2.
B) NADH.
C) NADPH.
D) riboflavin.
E) None of the above.

Question 29

Which enzyme(s) catalyze(s) the first step in de novo nucleotide biosynthesis?

A) aspartate transcarbamylase
B) nucleoside monophosphate kinase
C) glutamine phosphoribosyl amidotransferase
D) A and B
E) A and C

Question 30

Allopurinol is used to treat gout and is an inhibitor of the enzyme(s):

A) xanthine oxidase.
B) xanthine hydrolase.
C) hypoxanthine-guanine phosphoribosyltransferase.
D) All of the above.
E) None of the above.

Question 31

The competitive inhibitor(s) of dihydrofolate reductase is/are:

A) aminopterin
B) methotrexate
C) fluorouracil
D) A and B
E) B and C

Question 32

What is the advantage of channeling intermediates by carbamoyl phosphate synthetase?

Question 33

TMP is made from:

A) dTMP.
B) dUMP.
C) CTP.
D) ATP.
E) None of the above.

Question 34

The ultimate reductant in synthesis of deoxyribonucleotides is:

A) FADH2.
B) NADH.
C) NADPH.
D) quinone.
E) None of the above.

Question 35

Both de novo and salvage paths are used in the synthesis of:

A) ribonucleotides.
B) deoxyribonucleotides.
C) dideoxyribonucleotides.
D) All of the above.
E) None of the above.

Question 36

The synthesis of CTP from UTP requires UTP and:

A) glutamine and ATP.
B) glycine and ATP.
C) glutamine, ATP, and NADH.
D) All of the above.
E) None of the above.

Question 37

Why is nucleotide synthesis an important pathway for medical intervention? What types of disease could be treated using this information?

Question 38

Which amino acid side chain in thymidylate synthase activates the ring of dUMP, making C-5 a good nucleophile?

A) cysteine
B) aspartate
C) glutamine
D) tyrosine
E) serine

Question 39

The source(s) of NH2 groups in the synthesis of nucleotides is/are:

A) aspartate
B) glutamine
C) glycine
D) A and B
E) A, B, and C

Question 40

The displacing nucleophile in pyrimidine synthesis is typically:

A) ammonia or an amino group.
B) a metal ion.
C) coenzyme A.
D) All of the above.
E) None of the above.

Question 41

How is pyrimidine biosynthesis regulated?

Question 42

Why do purine salvage pathways save the cell energy?

Question 43

What is the disadvantage of methotrexate as a therapeutic agent?

Question 44

How is the reciprocal use of nucleotides useful in purine synthesis?

Question 45

What are advantages of high urate levels?

Question 46

How is ATCase, a key enzyme in pyrimidine biosynthesis, inhibited?

Question 47

Which vitamin supplement is taken during the first trimester of pregnancy to prevent the birth defect known as spina bifida?

Question 48

What is a general theme in purine ring synthesis, in terms of reaction logic and mechanism?