Question

Deletions occur most often in chromosomal fragments ______.

Options

• of polytene chromosomes

• without centromeres

• with centromeres

• with inversions

Answer 1

Deletions occur most often in chromosomal fragments without centromeres.

Explanation:

Deletions most often occur in chromosomal fragments that lack centromeres. Fragments without centromeres are lost during cell division because the centromere is required for proper attachment of the chromosome to the spindle fibers. Therefore, chromosome fragments without centromeres tend to be deleted more frequently. In contrast, fragments with centromeres are more likely to be retained by the cell. This is why deletions often involve acentric fragments (those without a centromere) which cannot be properly segregated during mitosis or meiosis.