Nucleotide Metabolism: Interactive Learning Quizzes for Biochemistry Students

Question 1

In the nucleoside salvage pathway, which enzyme enables the conversion of hypoxanthine to inosine monophosphate?

Accepted Answer

Hypoxanthine-guanine phosphoribosyltransferase

Answer

Phosphoribosyltransferase

Answer

Adenine phosphoribosyltransferase

Answer

Uridine kinase

Question 2

During the de novo synthesis of thymidine nucleotides, a specific substrate is required. Which of the following is a key substrate for this process?

Accepted Answer

Dihydrothymine

Answer

5-Fluorouracil

Answer

Uracil

Answer

Thymine

Question 3

The degradation of adenine to uric acid is facilitated by a specific enzyme. Which enzyme catalyzes this reaction?

Accepted Answer

Xanthine oxidase

Answer

Adenosine deaminase

Answer

Uric acid oxidase

Answer

Guanine deaminase

Question 4

Lesch-Nyhan syndrome, a genetic disorder, is associated with a deficiency in a specific enzyme. Which enzyme deficiency underlies this disorder?

Accepted Answer

Adenylosuccinate synthetase

Answer

Miller syndrome

Answer

Crigler-Najjar syndrome

Answer

Gaucher disease

Question 5

In the context of nucleotide metabolism, which class of drugs targets dihydrofolate reductase, thereby interfering with nucleotide synthesis?

Accepted Answer

Antimetabolites

Answer

Antibiotics

Answer

Immunosuppressants

Answer

Statins

Question 6

Which metabolic pathway generates inosine monophosphate (IMP), the precursor for both purine and pyrimidine nucleotides?

Accepted Answer

Pentose phosphate pathway

Answer

Glycolysis

Answer

Citric acid cycle

Answer

Urea cycle

Question 7

What is the primary biological role of S-adenosylmethionine (SAM)?

Accepted Answer

Methyl group donor in cellular processes

Answer

Coenzyme in protein synthesis

Answer

Activator of transcription factors

Answer

Inhibitor of RNA polymerase

Question 8

Which inherited disorder is caused by a deficiency of hypoxanthine-guanine phosphoribosyltransferase (HGPRT)?

Accepted Answer

Lesch-Nyhan syndrome

Answer

Cystic fibrosis

Answer

Phenylketonuria

Answer

Sickle cell anemia

Question 9

What is the end-product of purine catabolism in humans?

Accepted Answer

Uric acid

Answer

Allantoin

Answer

Ammonia

Answer

Creatinine

Question 10

Which enzymatic process converts nucleotides to nucleosides for salvage or degradation?

Accepted Answer

Hydrolysis

Answer

Phosphorylation

Answer

Deamination

Answer

Methylation

Question 11

What is the essential role of deoxyribonucleotides in DNA synthesis?

Accepted Answer

They serve as the building blocks for DNA elongation

Answer

They inhibit DNA polymerase activity

Answer

They stabilize DNA structure

Answer

They activate transcription factors

Question 12

Which molecule is the first precursor in the synthesis of purines?

Accepted Answer

Phosphoribosyl pyrophosphate (PRPP)

Answer

Glycine

Answer

Aspartate

Answer

Glutamine

Question 13

Identify the enzyme that regulates the rate of de novo purine biosynthesis.

Accepted Answer

Phosphoribosylglycinamide formyltransferase (GAR transformylase)

Answer

Inosine monophosphate (IMP) dehydrogenase

Answer

Adenylosuccinate synthetase

Answer

Hypoxanthine-guanine phosphoribosyltransferase (HGPRT)

Question 14

Which metabolic pathway is primarily responsible for the breakdown of purines?

Accepted Answer

Uric acid pathway

Answer

Glycolysis

Answer

Citric acid cycle

Answer

Pentose phosphate pathway

Question 15

Identify the enzyme that limits the rate of de novo pyrimidine biosynthesis.

Accepted Answer

Carbamoyl phosphate synthetase II (CPS II)

Answer

Aspartate transcarbamoylase

Answer

Dihydroorotase

Answer

Orotate phosphoribosyltransferase (OPRTase)

Question 16

Which metabolic pathway is involved in the degradation of pyrimidines?

Accepted Answer

Uridine diphosphate glucuronic acid (UDP-glucuronic acid) pathway

Answer

Glycolysis

Answer

Citric acid cycle

Answer

Pentose phosphate pathway

Question 17

What is the final product of pyrimidine catabolism?

Accepted Answer

β-Alanine

Answer

Allantoin

Answer

Ammonia

Answer

Carbon dioxide

Question 18

Which nucleotide serves as the primary energy currency within cells?

Accepted Answer

Adenosine triphosphate (ATP)

Answer

Guanosine diphosphate (GDP)

Answer

Cytidine triphosphate (CTP)

Answer

Uridine monophosphate (UMP)

Question 19

Which nucleotide is used as a precursor for DNA synthesis?

Accepted Answer

Deoxyadenosine triphosphate (dATP)

Answer

Cytidine triphosphate (CTP)

Answer

Guanosine triphosphate (GTP)

Answer

Uridine triphosphate (UTP)

Question 20

Identify the nitrogenous base that is NOT a purine:

Accepted Answer

Cytosine

Answer

Guanine

Answer

Adenine

Answer

Hypoxanthine

Question 21

What is the fundamental building block for the synthesis of both purines and pyrimidines?

Accepted Answer

Phosphoribosyl pyrophosphate (PRPP)

Answer

Deoxyribose-5-phosphate

Answer

Glucose-6-phosphate

Answer

Ribose-5-phosphate

Question 22

What is the ultimate degradation product of purines?

Accepted Answer

Uric acid

Answer

Ribose-5-phosphate

Answer

Inosine

Answer

Xanthine

Question 23

What is the primary role of nucleotides in energy metabolism?

Accepted Answer

Serving as energy carriers (e.g., ATP, GTP)

Answer

Enzymes

Answer

Structural components of nucleic acids

Question 24

Which cyclic nucleotide functions as a second messenger in cellular signaling?

Accepted Answer

Cyclic adenosine monophosphate (cAMP)

Answer

Guanosine triphosphate (GTP)

Answer

Thymidine

Answer

Deoxyadenosine triphosphate (dATP)

Question 25

Inhibition of which enzyme can result in gout?

Accepted Answer

Xanthine oxidase

Answer

Adenylosuccinate synthetase

Answer

Phosphoribosylglycinamide synthetase

Answer

Nucleoside phosphorylase

Question 26

Which genetic disorder is associated with defects in purine metabolism?

Accepted Answer

Lesch-Nyhan syndrome

Answer

Phenylketonuria

Answer

Cystic fibrosis

Answer

Tay-Sachs disease