Question

A normal chromosome has the gene sequence A B C D E F G • H I. Which of the following represents a pericentric inversion?

a) A B F G • H I
b) A B C D E F G • I H
c) A D C B E F G • H I
d) A B C D E H • G F I
e) None of the above

Answer 1

Option (b) A B C D E F G • I H represents a pericentric inversion as it includes the centromere and shows the inversion of the gene sequence after the centromere, which is characteristic of this type of chromosomal inversion.

Step-by-step explanation:

The question at hand involves understanding what a pericentric inversion is in a chromosome. A pericentric inversion includes the centromere and may result in the arms of the chromosome changing their relative lengths. This type of inversion involves the detachment, 180° rotation, and reinsertion of a part of the chromosome which includes the centromere. The given gene sequence A B C D E F G • H I exemplifies the structure of a normal chromosome, and our task is to identify which of the provided options represents a pericentric inversion. Among the choices, option (b) A B C D E F G • I H shows that the sequence after the centromere (•) has been inverted, with 'I' coming before 'H' instead of after. Therefore, option (b) aligns with the characteristics of a pericentric inversion as it includes the centromere and inverts the sequence post-centromere.