Question

If the homologous chromosomes do not separate in meiosis I, then one daughter cell from this division will have four copies of this chromosome and the other cell will have none. In meiosis II, sister chromatids will separate; leaving two gametes with two copies of the chromosome and two gametes with no copies of the chromosome.If two homologous chromosomes of chromosome # 12 fail to separate during meiosis I, how many copies of chromosome # 12 will the resulting gametes have?

Answer 1

If nondisjunction occurs during meiosis I for chromosome # 12, two gametes will have two copies of this chromosome, and two gametes will have none after meiosis II.

Step-by-step explanation:

When nondisjunction occurs during meiosis I, the cell division process where homologous chromosomes are supposed to separate, it can lead to some gametes having an abnormal number of chromosomes. In the case of chromosome # 12, if nondisjunction happens during meiosis I, and the homologous chromosomes do not separate, this would mean that one daughter cell would have both pairs of homologous chromosomes, thus having four copies of chromosome # 12. Consequently, after meiosis II occurs, when sister chromatids normally separate, two gametes will end up with two copies of chromosome # 12 (which is abnormal, as gametes should be haploid), while the other two gametes will have no copies of this chromosome at all.