Which mutation type involves a segment of DNA being reversed in orientation within the chromosome?

Which mutation type involves a segment of DNA being reversed in orientation within the chromosome?

• A. Translocation
• B. Insertion
• C. Inversion
• D. Duplication

Answer: (C)

This question tests understanding of chromosomal rearrangements, specifically when a segment is flipped in orientation within the chromosome. An inversion is a rearrangement where a DNA segment is cut out, reversed 180 degrees, and reinserted in the same location, so the genes there are in the opposite orientation but copy number remains unchanged. That exact description fits: the segment’s position is kept, but its orientation is reversed. In contrast, a translocation moves a segment to a new location or chromosome, an insertion adds new DNA into the chromosome, and a duplication creates an extra copy of a segment. Inversions can be further categorized as pericentric or paracentric depending on centromere involvement and can influence recombination during meiosis due to the need to form loops to align the inverted region.

This question tests understanding of chromosomal rearrangements, specifically when a segment is flipped in orientation within the chromosome. An inversion is a rearrangement where a DNA segment is cut out, reversed 180 degrees, and reinserted in the same location, so the genes there are in the opposite orientation but copy number remains unchanged. That exact description fits: the segment’s position is kept, but its orientation is reversed. In contrast, a translocation moves a segment to a new location or chromosome, an insertion adds new DNA into the chromosome, and a duplication creates an extra copy of a segment. Inversions can be further categorized as pericentric or paracentric depending on centromere involvement and can influence recombination during meiosis due to the need to form loops to align the inverted region.