Normally a male of Aa genotype would produce sperms with genotype(s) of A or a.
ID: 184243 • Letter: N
Question
Normally a male of Aa genotype would produce sperms with genotype(s) of A or a. Occasionally non-disjunction happens during meiosis II of spermatogenesis and consequently result in sperm with genotype (s) of 7. l: AA, Il: aa, IlI: Aa A. I only B. II only C. only D. I or II E. Ior lIl or II 8. The mating of an Aa male and an aa female produced an offspring with the genotype AAa. Therefore, the resulting offspring has 3 copies of gene 1 (trisomy for Chromosome 1). At what stage during meiosis did the non-disjunction event occur and in which parent? Check all of the options that apply. A. B. C. D. Paternal non-disjunction in meiosis I Maternal non-disjunction in meiosis I Paternal non-disjunction in meiosis II Maternal non-disjunction in meiosis II 9. (Bonus question) The mating of an Aa male and an aa female produced an offspring with the genotype gga, Therefore, the resulting offspring has 3 copies of gene 1 (trisomy for Chromosome 1). At what stage during meiosis did the non-disjunction event occur and in which parent? Check all of the answers that apply. A. Paternal non-disjunction in Meiosis I B. Maternal non-disjunction in Meiosis I C. Paternal non-disjunction in Meiosis II D. Maternal non-disjunction in Meiosis I1Explanation / Answer
7. Here the correct option is D. I or II. Because at meiosis I the homologous chromosomes are separated. They contain one 'A' allele and one 'a' allele. As non-disjunction occurs only meiosis II so there is no chance to get 'Aa' type of genotypes.
8. The correct option here is C. Paternal non-disjunction in meiosis II. From the question it is clearly seems that only the father contains 'A' alleles. So, after the meiosis II non-disjunction makes such type of sperms-a, a, AA, o. The 'AA' allele containg sperm when fuses with 'a' allele of ovum then the genotype of the offspring will be 'AAa' .
9. Here both the option, C and D are correct but the suitable answer is D. Maternal non-disjunction in meiosis II. Because the chance for non-disjunctioning of 'aa' genotype and chances of production of ovum(aa) is higher than 'aa' genotype containg sperm.
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