Which chromosomal mutation reverses the direction of parts of a chromosome?

• A. Translocation chromosomal mutation
• B. Inversion chromosomal mutation
• C. Duplication chromosomal mutation
• D. Deletion chromosomal mutation

Answer: (B)

Reversing the direction of a chromosome segment happens when a section of DNA flips and is reinserted in the opposite orientation, so the gene order within that region is reversed. This is exactly what an inversion does: two breaks occur, the segment in between rotates 180 degrees, and then reattaches. The overall amount of genetic material can stay the same, but the orientation of the genes is opposite, which can affect gene regulation or how chromosomes pair up during meiosis.

The other mutations don’t reverse orientation within the same chromosome. A translocation swaps segments between chromosomes or moves a piece to a different chromosome, changing location rather than direction. A duplication increases the number of copies of a segment, altering dosage. A deletion removes a segment, reducing genetic material.