Which of the following offspring genotypes could result from the fertilization of an egg that had undergone nondisjunction in me

Question

6 days ago

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Which of the following offspring genotypes could result from the fertilization of an egg that had undergone nondisjunction in me

iosis II with a normal haploid sperm? (Because a nondisjunction event in meiosis II could involve the chromosome containing gene A or the chromosome containing gene a, be sure to consider both possibilities in your final answer .)

Biology

2 answers:

inysia [665] · Answer 1 · 2026-02-27T00:36:37+03:00

Answer:

AAa, aaa, Aa, aa or a.

Explanation:

The situation where homologous chromosomes remain together instead of separating into individual daughter cells is termed non-disjunction.

In this case, the mother possesses a heterozygous gene (Aa), during oogenesis, at anaphase of meiosis 1. Each gene separates, migrating to different oocytes, or daughter cells.

However, during meiosis 2, rather than each chromosome separating at metaphase 2, either the A or a gene can fail to separate and both migrate into the same daughter cell. Due to the randomness of this process, the resulting oocyte may contain;

AA/aa,- if one of A or a hasn’t separated and paired with another,

or

A /a. if no additional copies paired due to some oocytes having extras

or

(0)- representing nothing - should extra copies prevent equal distribution in non-disjunction oocytes.

If any of these cells are fertilized by a haploid sperm from a father with homozygous recessive gene a, during random fertilization, the resulting combinations of chromosomes in the offspring could include:

resulting in non-disjoined zygotes of types AAa, aaa, Aa, aa or a.

Tresset [665] · Answer 2 · 2026-02-27T00:36:25+03:00

Answer:

See the explanation below

Explanation:

Non-disjunction occurs due to the failure of homologous chromosomes to separate during meiosis.

This leads to gametes (resulting daughter cells) having either additional or fewer chromosomes compared to a standard gamete.

When a gamete with excess chromosomes unites with a normal gamete, the offspring will exhibit an extra chromosome (resulting in trisomy).

Conversely, if a gamete has one less chromosome than typical and fuses with a normal gamete, the offspring will end up with a deficit of one chromosome (monosomy).

If a chromosome with gene Aa undergoes non-disjunction during meiosis, the resulting gametes may either carry both A and a or none.

<pWhen a gamete with an Aa gene fertilizes a standard haploid sperm (a), the resulting zygote will possess the genotype Aaa.

If a gamete that lacks any chromosome fertilizes a normal haploid sperm, the offspring will have the genotype a.