Final answer:
A chromosome duplication with an inverted duplicated region is called a reverse duplication. This structural change occurs when a chromosome segment inverts its orientation upon reinsertion. Such inversions can lead to various outcomes depending on whether they disrupt gene sequences.
Step-by-step explanation:
A chromosome duplication in which the duplicated region is inverted is called a reverse duplication. This occurs when a chromosome segment breaks away, undergoes a 180° rotation, and reinserts into the chromosome in the opposite orientation. Inversions can have various consequences, ranging from mild effects if they do not disrupt gene sequences to producing aneuploid gametes or causing physical and mental abnormalities if the structural rearrangement affects gene function significantly.
It's important to understand that such duplications and inversions occur during DNA replication or repair processes. Cytologists look for these structural rearrangements during meiosis, when homologous chromosomes pair up. Incorrect gene orientation due to inversion can lead to improper recombination, resulting in the gain or loss of genetic material in gametes.
The process of inversion is distinct from other chromosomal anomalies such as nondisjunction, which leads to aneuploid gametes, or translocations, where segments of nonhomologous chromosomes exchange places.