Nondisjuction is a cell division error in which either homologous chromosomes or sister chromatids fail to separate and thus do not migrate to opposite poles. It is responsible for conditions such as monosomy (one member of a chromosome pair is missing) and trisomy (three copies of a chromosome is present rather than two).
Nondisjunction can occur during the first or second meiotic division.
Part A- Jill is heterozygous for gene A and is going to have a child with Jack, who is homozygous recessive for gene A.
Which of the following offspring genotypes could result from fertilization of a normal haploid sperm with an egg that had undergone nondisjunction in meiosis I?
Check all that apply.
1)AAa
2)Aaa
3)aaa
4)Aa
5)aa
6)a
I put AAa, Aaa, Aa, but it was not correct
Part B-
Which of the following offspring genotypes could result from fertilization of a normal haploid sperm with an oocyte that had undergone nondisjunction in meiosis II?
Check all that apply.
1)AAa
2)Aaa
3)aaa
4)Aa
5)aa
6)a
Part E-
If Jack and Jill have a child with an aaa genotype, during which meiotic division, and in which parent, could nondisjunction have occurred?
Check all that apply.
1) Meiosis I in the mother
2 Meiosis II in the mother
3) Meiosis I in the father
4) Meiosis II in the father
The answer is not Meisis I in the mother