Question

Assertion: In sickle cell anaemia, the codon GAG is replaced by GUG.

Reason: The gene for the above mutation occurs on the Y-chromosome.

Options

• Both assertion and reason are true, and reason is the correct explanation of the assertion.

• Both assertion and reason are true, but reason is not the correct explanation of assertion.

• Assertion is true but reason is false.

• Both assertion and reason are false.

Answer 1

Assertion is true but reason is false.

Explanation:

In sickle cell anaemia, the codon GAG is indeed replaced by GUG causing substitution of glutamic acid by valine in the β-globin chain. However, this gene mutation is on an autosome, not on the Y-chromosome; sickle cell anaemia is autosomal recessive, affecting both sexes equally.