Sign In

Essential Biochemistry - Nucleic Acid Metabolism (Section 1)

1
Which of the following compounds is formed from Xanthine by Xanthine oxidase?
Answer
(A)
Uric acid
2
Which of the following is a characteristic feature of primary gout?
Answer
(C)
Result of an inborn error of metabolism
3
What is the role of allopurinol in the treatment of gout?
Answer
(C)
Inhibits xanthine oxidase
4
Which of the following compounds is formed as a result of purine catabolism?
Answer
(A)
Uric acid
5
Which enzyme is deficient in Lesch-Nyhan syndrome?
Answer
(B)
HGPRT
6
What compound is converted to UMP in the pyrimidine synthesis pathway?
Answer
(A)
Orotate
7
What is the most common type of renal stone in patients with Lesch-Nyhan syndrome?
Answer
(A)
Uric acid stones
8
What are some of the symptoms of primary gout?
Answer
A
B
C
D
9
Which of the following are end products of purine catabolism?
Answer
(A)
Uric Acid
10
Which of the following is directly inhibited by allopurinol?
Answer
(A)
Xanthine oxidase
11
Which of the following compounds is elevated in Lesch-Nyhan syndrome?
Answer
(A)
Uric acid
12
Which enzyme is directly responsible for the de novo synthesis of purines?
Answer
(C)
PRPP amidotransferase
13
What is the committed step in the synthesis of pyrimidine nucleotides?
Answer
(A)
Formation of carbamoyl phosphate
14
Which of the following is the precursor to UMP in the de novo synthesis of pyrimidines?
Answer
(A)
Orotate
15
Which of the following is true regarding Lesch-Nyhan Syndrome?
Answer
(B)
It is an X-linked recessive disorder.
16
What is the role of PRPP amidotransferase?
Answer
(A)
Catalyzes the first committed step in purine nucleotide synthesis.
17
Which of the following is a direct precursor of the pyrimidine base cytosine?
Answer
(A)
Uracil
18
Which of the following is a characteristic of primary gout?
Answer
(B)
It's inherited and results from a defect in purine metabolism
19
Which of the following enzymes are involved in de novo synthesis of pyrimidine nucleotides?
Answer
A
B
C
20
Which of the following enzymes is inhibited by the drug allopurinol?
Answer
(B)
Xanthine oxidase
21
Which of the following is a precursor for the pyrimidine ring?
Answer
(A)
Aspartate
22
What enzyme is directly inhibited by IMP, AMP, and GMP in purine synthesis?
Answer
(B)
PRPP amidotransferase
23
Which of the following is a characteristic of SCID due to ADA deficiency?
Answer
(A)
Accumulation of deoxyadenosine and dATP in the lymphocytes.
24
In the de novo synthesis of purines, what molecule provides the carbon atom at position C-2?
Answer
(D)
N10-formyltetrahydrofolate
25
Which enzyme is deficient in Lesch-Nyhan syndrome?
Answer
(B)
Hypoxanthine-guanine phosphoribosyltransferase (HGPRT)
26
Which of the following is a characteristic of type I orotic aciduria?
Answer
(A)
Deficiency in both orotate phosphoribosyltransferase and orotidine 5'-phosphate decarboxylase.
27
Which of the following statements best describes the role of salvage pathways?
Answer
A
B
C
28
What is the committed step in the de novo synthesis of pyrimidine nucleotides?
Answer
(A)
Formation of Carbamoyl phosphate
29
Which of the following is the first step in the de novo synthesis of pyrimidine nucleotides?
Answer
(A)
Synthesis of carbamoyl phosphate
30
Which enzyme is directly inhibited by IMP, AMP, and GMP in purine synthesis?
Answer
(B)
PRPP amidotransferase
31
Which enzyme catalyzes the reaction of carbamoyl phosphate formation in pyrimidine synthesis?
Answer
(B)
Carbamoyl phosphate synthetase II
32
What is the initial substrate for pyrimidine synthesis?
Answer
(B)
Carbamoyl phosphate
33
Which of the following is the role of Adenylosuccinate synthetase?
Answer
(A)
It converts IMP to AMP.
34
Which of the following is a characteristic of Lesch-Nyhan syndrome?
Answer
(C)
Self-mutilation behavior
35
Which of the following statements best describes the role of feedback inhibition in purine synthesis?
Answer
(B)
Purine nucleotides inhibit the enzyme, PRPP amidotransferase.
36
Which of the following statements about salvage pathways is correct?
Answer
(B)
They use preformed bases to synthesize nucleotides.
37
Which of the following is not a precursor in the synthesis of purines?
Answer
(D)
Leucine
38
Which of the following amino acids provides a nitrogen atom that becomes a part of the purine ring?
Answer
(A)
Glycine
39
In the de novo synthesis of pyrimidines, what is the role of aspartate?
Answer
(A)
It provides nitrogen atoms to the ring
40
Which of the following is the substrate for xanthine oxidase?
Answer
(A)
Hypoxanthine
41
What is the role of xanthine oxidase?
Answer
(A)
It converts hypoxanthine to xanthine and xanthine to uric acid.
42
Which of the following is a characteristic of type I orotic aciduria?
Answer
(A)
Deficiency in both orotate phosphoribosyltransferase and orotidine 5'-phosphate decarboxylase.
43
Which of the following reactions requires tetrahydrofolate?
Answer
(C)
Addition of a carbon to the purine ring.
44
What steps are catalyzed by the enzyme complex UMP synthase?
Answer
A
C
45
Which of the following is the direct precursor of orotate in pyrimidine synthesis?
Answer
(C)
Dihydroorotate
46
In de novo pyrimidine synthesis, what is the role of dihydroorotase?
Answer
(A)
Catalyzing the formation of orotate from dihydroorotate.
47
What is the role of tetrahydrofolate in purine synthesis?
Answer
(A)
Transfer of a carbon unit to the purine ring.
48
Which of the following enzymes is involved in the synthesis of pyrimidine nucleotides?
Answer
A
B
C
49
Which of the following is/are associated with the clinical manifestation of Lesch-Nyhan syndrome?
Answer
A
B
C
D
50
Which of the following are end products of pyrimidine catabolism?
Answer
A
B
D