Question

What would happen if one of the chromosomes in a homologous pair failed to separate from its homologue at the end of metaphase I? What would the final daughter cells look like?

Answer 1

The correct answer is: daughter cells will have abnormal chromosome numbers and this condition is called aneuploidy.

Nondisjunction is the failure of homologous chromosomes (or sister chromatids) to separate during the process of cell division and consequently lead to aneuploidy. There are three forms of nondisjunction:

• Nondisjunction in meiosis I (pair of homologous chromosomes unable to separate in meiosis I),

• Nondisjunction in meiosis I (sister chromatids unable to separate during meiosis II), and

• Nondisjunction in mitosis (failure of sister chromatids to separate during mitosis)

Answer 2

Non disjunction at meiosis I results in formation of two daughter cells with one extra chromosome (n+1) and two daughter cells with one less chromosome (n-1).

Step-by-step explanation:

Failure of homologous chromosomes to separate from each other by the end of metaphase I leads to nondisjunction. The process forms two types of daughter cells: Two daughter cells with n+1 chromosomes (presence of one extra copy of chromosome) and rest two with n-1 chromosomes (absence of one chromosome from the genome).