What is termed when a chromosome section is broken off and reattached in reverse order?

The term used to describe a chromosome section that has been broken off and reattached in reverse order is referred to as inversion. This genetic event involves a segment of a chromosome that detaches and then re-inserts itself, but flipped from its original orientation. As a result, the genes within this inverted segment can have altered expression patterns, potentially leading to changes in the organism's phenotype.

In contrast, deletion involves the loss of a chromosome segment, which can result in the absence of certain genes. Translocation refers to the rearrangement where a segment of one chromosome is moved to a different chromosome, which can lead to various genetic disorders. Nondisjunction is the failure of homologous chromosomes or sister chromatids to separate properly during cell division, resulting in an abnormal number of chromosomes. Each of these terms describes different types of chromosomal abnormalities, but inversion specifically relates to the reversal of a segment within the same chromosome.