Question

Which chromosomal defect is caused when part of a chromosome breaks off and reattaches backward on the same chromosome?

Answer 1

The right answer is inversion.

Inversion is a genetic mutation characterized by the end-to-end reversal of a portion of chromatid on a chromosome.

In other words, it is a double break then it is replaced after rotation of 180 ° of a chromosome segment (backward insertion).

We distinguish :

Paracentric inversions:  The centromere in the chromosome is not included in the inversion.

Pericentric inversions:  The centromere is included in the inversion which transforms a metacentric chromosome into an acrocentric chromosome.

Answer 2

The correct answer is option A, inversion

Reason -

In the process of inversion a part of DNA gets inverted which simply means that a section of DNA breaks off  from a section and then attached to the same section in the reversed direction.  

For example –  

Let’s assume a nucleoside arrangement given below –  

ATT GCC ATA GCG

So now if inversion takes place here for the first two set of codons (i.e ATT GCC), then the new structural arrangement would be as follows –  

GCC ATT ATA GCG