Chromosomes usually appear in pairs. If there are three chromosomes where there should be two, what kind of mutation is this?

1 Answer
Apr 28, 2016

This is a genetic mutation called Nondisjunction.

Explanation:

When chromosomes don't properly separate during meiosis, there will be an uneven number of chromosomes in pairs. It could be trisomy or monosomy. Trisomy is when you have 3 chromosomes in a pair and monosomy is when you have only 1 chromosome in a pair. These cause genetic diseases such as monosomy-21 (21th pair in the karyotype) which is also known as down syndrome.