Final answer:
Chromosome inversions are a type of structural rearrangement in chromosomes that do not involve the loss or gain of genetic material. They often only change the gene orientation on the chromosome and usually have mild effects unless they disrupt a gene sequence.
Step-by-step explanation:
Chromosome inversions are a type of structural rearrangement in chromosomes where a part of the chromosome detaches, rotates 180 degrees, and reinserts itself. Unlike other chromosomal mutations, inversions do not involve the loss or gain of genetic material. They often only change the orientation of genes on the affected chromosome, which usually has mild effects unless they disrupt a gene sequence. Inversions may occur naturally or as a result of mechanical shear or the action of transposable elements.