Answer:
See explanation below
Explanation:
Non-disjunction occur as a result of lack of separation of homologous chromosomes during meiosis.
As a result, the gametes (the daughter cells formed) produced end up having extra or lesser chromosomes as compared to a normal gamete.
When a gamete with extra chromosome fertilizes a normal gamete, the resulting offspring will have an extra chromosome (trisomy condition).
On the other hand, when a gamete with one less chromosome than normal fertilizes a normal gamete, the resulting offspring will have one less chromosome than normal offspring (monosomy condition).
Assuming a chromosome with Aa gene undergoes non disjunction during meiosis, the resulting gametes either contain both A and a chromosome or contain no chromosome at all.
If Aa gamete is fertilized by a normal haploid sperm (a), the resulting zygote will have the genotype Aaa.
If a gamete with no chromosome at all fertilizes a normal haploid sperm, the resulting offspring will have the genotype a.
Answer:
AAa, aaa, Aa, aa or a.
Explanation:
The phenomenon where homologous chromosome failed to separate into new daughter cells , but remained joined together so that one daughter cell has extra number of chromosomes while the other daughter cell has empty chromosome in nucleus is called non dis junction.
In this present scenario in the mother with heterozygous gene (Aa) , during oogenesis at anaphase of meiosis 1. each of the gene separate, and move to the different oocytes -daughter cells .
However, at meiosis 2, instead of the each chromosomes to undergo centromere separation at metaphase ii ,either of A or a -genes, may failed to do this and rather migrates into same oocyte -daughter cells. Because this is a random events, the oocyte may have;
AA/aa,-assuming one A or a failed to separate and joined with another,
or
A /a. assuming no extra to pair because of extra copies in some oocytes
or
(0)-nothing.-assuming extra copies has prevented equal distribution in non-dijuction oocytes.
if either of these cells above is fertilized by haploid sperm of father with homozygote recessive gene a in random fertilisation; the haploid sperm with gene a after fertilization produce either of offspring of the following chromosomes combinations;
as a result of non-dis-joined zygotes AAa, aaa, Aa, aa or a.
