Final answer:
Chromosome inversions involve the detachment, rotation, and reinsertion of parts of a chromosome. They can occur naturally or be caused by transposable elements. Inversions only change gene orientation and usually have mild effects, but they can cause functional changes in gene expression.
Step-by-step explanation:
A chromosome inversion is the detachment, 180° rotation, and reinsertion of part of a chromosome. Inversions may occur in nature as a result of mechanical shear, or from the action of transposable elements (special DNA sequences capable of facilitating the rearrangement of chromosome segments with the help of enzymes that cut and paste DNA sequences). Unless they disrupt a gene sequence, inversions only change the orientation of genes and are likely to have more mild effects than aneuploid errors. However, altered gene orientation can result in functional changes because regulators of gene expression could be moved out of position with respect to their targets, causing aberrant levels of gene products.