Genetic Code and Codon Usage Practice Questions

Question 1

What is the function of the UGA codon?

Accepted Answer

Terminates protein synthesis

Answer

Initiates transcription

Answer

Translates

Answer

None of the options

Question 2

Mark the false statement regarding mitochondrial DNA:

Accepted Answer

Does not show heteroplasmy

Answer

AGA and AGG are stop codons in mitochondrial DNA

Answer

Kearns-Sayre Syndrome is a large deletion in mitochondrial DNA

Answer

1% of cellular DNA, 13 proteins of respiratory chain

Question 3

If a sequence of 4 nucleotides codes for 1 amino acid, how many amino acids can be theoretically formed?

Accepted Answer

256

Answer

4

Answer

64

Answer

16

Question 4

Which condition is associated with defects in pre-mRNA splicing and SMN protein dysfunction?

Accepted Answer

Spinal muscular atrophy

Answer

Sickle cell disease

Answer

Huntington's disease

Answer

α-Thalassemia

Question 5

What is the primary function of exonuclease in DNA replication?

Accepted Answer

Proofreading

Answer

Polymerization

Answer

Chain elongation

Answer

Termination

Question 6

Which type of bonds are represented by the dotted lines in the image? (AIIMS Nov 2017)

Accepted Answer

Hydrogen bond

Answer

Covalent bond

Answer

Ionic bond

Answer

Phosphodiester

Question 7

During DNA replication, if the template strand has the sequence 5'-GATTACA-3', what is the sequence of the complementary strand?

Accepted Answer

5'-TGTAATC-3'

Answer

5'-GATTACA-3'

Answer

3'-GATTACA-5'

Answer

5'-ACATTAG-3'

Question 8

Nucleotides serve all of the following roles, EXCEPT:

Accepted Answer

Structural component of membrane

Answer

Monomeric units of nucleic acids

Answer

Mediators in cellular signalling

Answer

Source of energy

Question 9

What is the end product of pyrimidine catabolism?

Accepted Answer

Carbon dioxide (CO2) and water (H2O)

Answer

Ammonia (NH3)

Answer

Both ammonia and carbon dioxide/water

Answer

None of the above

Question 10

Which of the following compounds is an analogue of hypoxanthine?

Accepted Answer

Allopurinol

Answer

Arabinoside C

Answer

Ribose phosphate

Answer

5-phosphoribosylpyrophosphate (PRPP)

Genetic Code and Codon Usage — MCQs

Genetic Code and Codon Usage — MCQs

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