3- A crossing over occurred between the two non- sister chromatids of the X chro

Question

3- A crossing over occurred between the two non-sister chromatids of the X chromosomes in Mary’s primary oocyte that resumed meiosis this month, and as a result, the ‘A’ and ‘a’ alleles were exchanged. What would be the genotype of the first polar body for gene A, and what is the chance that the ovulated egg cell will carry the ‘A’ allele? (Draw the chromosomes with the corresponding alleles during oogenesis)

A- AA, Zero chance
B- aa, 100% chance
C- Aa, 50% chance
D- AA or Aa, 75% chance
E- AA or aa, the chance cannot be determined

F- Aa or aa, 25% chance

G- AAaa, 50% chance

Explanation / Answer

Option C. Aa because both alleles exchanged their positions, so situation is still same. Also polar body is haploid. The egg cell has 50% chance of receiving either the A or a allele.

Related Questions

Navigate

• Browse (All)
• Browse 3
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.