Question

Imagine there is a cell with 2n = 4 chromosomes. The cell undergoes meiosis, but there is an event of nondisjunction in meiosis I: homologous chromosome pair fails to separate properly during metaphase I. Which of the following is the MOST likely end result of meiosis in this case?

Group of answer choices 4 daughter cells; n = 3, n = 1, n = 2, n = 2 2 daughter cells; n =3, n = 1 4 daughter cells: n = 3, n = 3, n = 1, n = 1 2 daughter cells; n = 2, n = 2

Answer 1

The Correct answer is third option i.e. 4 daughter cwlls; n=3, n=3, n=1, n=1. Non-disjunction is of two types. There may be failure of separation of homologous chromosomes in Meiosis-I or there may be failure of separation of sister chromatids in meiosis-II. Due to this, the gametes in daughter cells ended up having one or more extra chromosomes or they will be with fewer chromosomes than complete set. Please find the attached diagram of non-disjunction in Meiosis-I where homologous chromosomes failed to separate properly.