What is the term for a chromosome change resulting from a fragment attaching to a nonhomologous chromosome?

The term that describes a chromosome change resulting from a fragment attaching to a nonhomologous chromosome is translocation. This process involves the rearrangement of genetic material, typically where a segment of one chromosome breaks off and becomes attached to another chromosome that is not its homologous partner. This can lead to significant changes in gene expression and can have various effects on an organism's phenotype.

In contrast, duplication refers to a scenario where a segment of a chromosome is copied and integrated into the same chromosome, resulting in two copies of that segment. Inversion involves a segment of a chromosome being flipped and reinserted into the same chromosome, which does not entail the interaction with a nonhomologous chromosome. Insertion typically refers to the insertion of additional genetic material into a chromosome from another source but is not specific to nonhomologous interactions.

Thus, translocation specifically addresses the movement of DNA segments between different chromosome pairs, making it the correct term for this type of chromosome alteration.