Question

One of the parents of a cross has mutation in its mitochondrion. In that cross, that parent is taken as male. During segregation of $F_2$ progenies that mutation is found in

• A. One third of the progenies
• B. None of the progenies
• C. All the progenies
• D. Fifty percent of the progenies

Answer 1

The Correct Option is B

To solve this question, we need to understand how mitochondrial inheritance works in biological organisms, especially in the context of genetics and heredity.

Mitochondrial DNA (mtDNA) is inherited maternally, which means it is passed down from the mother to the offspring. This means only the mother contributes to the mitochondrial DNA of the child, unlike nuclear DNA, which is inherited from both parents. As a result, any mutation present in mitochondrial DNA will be passed on to all offspring by the mother, not by the father or male parent.

In this scenario, where the question specifies that the mutation in the mitochondrion is in the male parent, we need to understand that:

• The male parent's mtDNA does not get passed to the progeny. Therefore, any mitochondrial mutation in the male parent will not be inherited by the progeny.

Now, let's consider the given options:

• One third of the progenies: This option suggests that some but not all progeny inherit the mutation, which is not possible because none of the progeny inherit mitochondrial DNA from the father.
• None of the progenies: This option is accurate because progeny inherit mitochondrial DNA only from the mother, so no offspring of a male with mitochondrial mutation will carry this mutation.
• All the progenies: This option is only possible if the mother had the mutation, which is not the case here.
• Fifty percent of the progenies: Similar to the first option, this is not possible as mitochondrial DNA is not inherited from the father.

The correct answer, therefore, is None of the progenies because the mitochondrial mutation in the male parent does not get passed to the offspring. All progeny receive their mtDNA solely from their mother, regardless of any mutations the father may have in their mitochondria.