Which mutation involves the two DNA strands flipping positions, or turning around?

Which mutation involves the two DNA strands flipping positions, or turning around?

• A. Transversion
• B. Deletion
• C. Inversion
• D. Duplication

Answer: (D)

What this item tests is how chromosomal rearrangements change the orientation of a DNA segment. Flipping positions refers to the segment being inverted, meaning it is reversed end-to-end within the chromosome. For example, a sequence like ABCDE would become EDCBA in the same genomic location after inversion. This rearrangement changes the order and direction of the bases in that region without necessarily changing the amount of DNA. This is different from duplication, which would produce an extra copy of a segment rather than reversing its orientation. Deletion removes a segment, reducing material, and transversion is a single-base substitution where a purine is replaced by a pyrimidine or vice versa, not a large-scale rearrangement. Inversions can be pericentric (including the centromere) or paracentric (excluding the centromere) and can impact gene function or recombination, even if the total amount of DNA remains the same. The described mutation is inversion.

What this item tests is how chromosomal rearrangements change the orientation of a DNA segment. Flipping positions refers to the segment being inverted, meaning it is reversed end-to-end within the chromosome. For example, a sequence like ABCDE would become EDCBA in the same genomic location after inversion. This rearrangement changes the order and direction of the bases in that region without necessarily changing the amount of DNA.

This is different from duplication, which would produce an extra copy of a segment rather than reversing its orientation. Deletion removes a segment, reducing material, and transversion is a single-base substitution where a purine is replaced by a pyrimidine or vice versa, not a large-scale rearrangement. Inversions can be pericentric (including the centromere) or paracentric (excluding the centromere) and can impact gene function or recombination, even if the total amount of DNA remains the same. The described mutation is inversion.