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Essential Biochemistry - Nucleic Acid Metabolism (Section 2)

1
In the synthesis of pyrimidine nucleotides, what is the role of dihydroorotate dehydrogenase?
Answer
(A)
Catalyzes the formation of orotate from dihydroorotate.
2
What is the primary function of APRT in nucleotide metabolism?
Answer
(C)
Purine salvage pathway
3
What is the role of orotidine 5'-phosphate decarboxylase?
Answer
(C)
Converts orotidine 5'-phosphate to UMP.
4
Which of the following is a characteristic of Lesch-Nyhan syndrome?
Answer
(B)
Excessive uric acid production
5
In Lesch-Nyhan syndrome, there is an overproduction of:
Answer
(D)
All of the above
6
Which enzyme(s) are involved in the salvage pathway for purines?
Answer
(C)
Both APRT and HGPRT
7
Which of the following amino acids is not directly involved in the de novo synthesis of purines?
Answer
(D)
Alanine
8
Which of the following is the role of PRPP synthetase in purine biosynthesis?
Answer
(B)
It is involved in the synthesis of PRPP from ribose-5-phosphate.
9
Which enzyme catalyzes the conversion of IMP to GMP?
Answer
(A)
Inosinate dehydrogenase
10
Which of the following are purine bases?
Answer
A
B
11
What is the key enzyme inhibited by allopurinol?
Answer
(A)
Xanthine oxidase
12
Which enzyme is directly involved in the formation of IMP?
Answer
(A)
PRPP amidotransferase
13
Which of the following processes are involved in the regulation of purine biosynthesis?
Answer
A
B
C
14
What are potential causes of secondary gout?
Answer
A
B
C
D
15
Which of the following is a key enzyme in the regulation of purine synthesis?
Answer
(A)
PRPP synthetase
16
What is the major function of the salvage pathway?
Answer
(B)
Recycling of free bases.
17
In which organ does the catabolism of purines primarily occur?
Answer
(A)
Liver
18
Which of the following is a characteristic of gout?
Answer
(B)
It is a metabolic disorder associated with an elevated level of uric acid in the serum.
19
In the de novo synthesis of purines, what molecule contributes to the formation of the purine ring?
Answer
(D)
All of the above
20
What is the role of adenosine deaminase?
Answer
(A)
Catalyzes the conversion of adenosine to inosine.
21
What are the components of a nucleotide?
Answer
A
B
C
22
What is the role of inosinate dehydrogenase in purine synthesis?
Answer
(A)
Catalyzes the conversion of IMP to GMP.
23
Which enzyme catalyzes the committed step in purine synthesis?
Answer
(B)
PRPP amidotransferase
24
Which of the following are components of a nucleotide?
Answer
A
B
C
25
Which of the following is the major end product of purine catabolism in humans?
Answer
(A)
Uric acid
26
Which of the following is/are involved in the regulation of purine nucleotide synthesis?
Answer
A
B
C
27
In the purine salvage pathway, what is the role of HGPRT?
Answer
(A)
Synthesizes IMP and GMP from hypoxanthine and guanine, respectively.
28
Which enzyme is involved in the conversion of IMP to AMP?
Answer
(B)
Adenylosuccinate synthetase
29
What is the role of orotate phosphoribosyltransferase?
Answer
(A)
Adds a PRPP to orotate.
30
What is the role of orotate phosphoribosyltransferase?
Answer
(C)
Adds a PRPP to orotate.
31
Which of the following is the substrate for the synthesis of UMP in pyrimidine nucleotide biosynthesis?
Answer
(C)
Dihydroorotate
32
What enzyme is deficient in type I orotic aciduria?
Answer
A
B
33
Which of the following is a precursor for the de novo synthesis of purine nucleotides?
Answer
(D)
All of the above
34
What are the end products of pyrimidine catabolism?
Answer
A
B
C
35
Which enzyme catalyzes the formation of carbamoyl phosphate in pyrimidine synthesis?
Answer
(A)
Carbamoyl phosphate synthetase II
36
Which of the following is involved in the synthesis of pyrimidine nucleotides?
Answer
A
B
C
37
Which of the following is the result of a deficiency in adenosine deaminase?
Answer
(A)
Severe Combined Immunodeficiency (SCID).
38
What is the role of HGPRT in purine metabolism?
Answer
(C)
It is involved in the salvage pathway, converting hypoxanthine and guanine into IMP and GMP, respectively.
39
Which of the following is a key characteristic of Gout?
Answer
(A)
Hyperuricemia
40
What is the source of nitrogen atoms at positions N-1 and N-3 in the purine ring?
Answer
(B)
Glutamine and Aspartate
41
In the de novo synthesis of pyrimidines, what is the source of nitrogen atoms for the pyrimidine ring?
Answer
(B)
Aspartate
42
Which of the following is/are involved in purine catabolism?
Answer
(C)
All of the above
43
Which of the following compounds contributes to the purine ring synthesis?
Answer
A
B
C
44
Which of the following are associated with SCID caused by ADA deficiency?
Answer
A
B
C
45
Which of the following is required for the formation of UMP?
Answer
(A)
Orotate and PRPP
46
What is the role of Adenosine Deaminase (ADA) in the body?
Answer
(A)
It converts adenosine to inosine.
47
What is the role of dihydroorotate dehydrogenase in pyrimidine synthesis?
Answer
(A)
It converts dihydroorotate to orotate.
48
Which of the following are true about SCID caused by adenosine deaminase deficiency?
Answer
A
B
C
49
Which compound is directly produced by xanthine oxidase?
Answer
(A)
Uric acid
50
Which of the following is a key regulatory enzyme in purine biosynthesis?
Answer
(C)
PRPP synthetase