Which chromosomal mutation occurs when part of a chromosome breaks off and attaches to a non-homologous chromosome?

• A. Translocation chromosomal mutation
• B. Deletion chromosomal mutation
• C. Duplication chromosomal mutation
• D. Inversion chromosomal mutation

Answer: (A)

Translocation is the chromosomal change described here: a piece of one chromosome breaks off and attaches to a different, non-homologous chromosome. This kind of rearrangement can happen in two ways—reciprocal translocation, where segments are exchanged between two chromosomes, or nonreciprocal translocation, where a fragment moves to another chromosome without an exchange. This differs from deletion (loss of a part of a chromosome), duplication (extra copy of a part), or inversion (a segment is flipped in orientation within the same chromosome). Translocations can disrupt genes at the breakpoints or create fusion genes, and they can affect how chromosomes segregate during meiosis, sometimes leading to unbalanced gametes. A well-known example is the Philadelphia chromosome, a translocation between chromosomes 9 and 22.