Final answer:
The question discusses a paracentric chromosome inversion, where part of a chromosome is flipped and rejoined without including the centromere. This can result in non-viable gametes due to the absence of a centromere after meiotic crossing over. Chromosome inversions can have evolutionary implications, as evidenced by a pericentric inversion on chromosome 18 in humans.
Step-by-step explanation:
The subject in question refers to the phenomenon of a chromosome inversion, specifically a paracentric inversion. A paracentric inversion occurs when a section of a chromosome breaks at two points and is flipped 180 degrees before rejoining the chromosome. This type of inversion does not include the centromere, the part of the chromosome involved in cell division.
During meiosis, the process by which sex cells are created, crossing over can happen within a paracentric inversion. This crossing over can lead to the production of a chromatid that lacks a centromere, which generally leads to non-viable gametes because the centromere is essential for proper chromosome alignment and segregation during cell division.
Such chromosome inversions can have evolutionary significance. For instance, a pericentric inversion on chromosome 18 is believed to have played a role in human evolution, distinguishing us from our closest relatives, the chimpanzees.