Question

A gene mutation causes sister chromatids to be separated into two daughter cells in the first nuclear division (Meiosis I) during meiosis. What a major defect would happen in the resulting haploid cells upon the completion of the second nuclear division (Meiosis II)

Answer 1

Mutation is the change in the nucleotide sequence of a DNA which causes difference in the amino acid synthesis from the original one and also causes difference in characteristics of the organisms. In meiosis cell division 4 cells are formed from the one parent cell. So each newly formed cells contains one haploid set of the chromosome of the parent cell. Each haploid chromosome of the daughter cell resembles with the nucleotide sequence of the DNA of parent cell. But when mutation takes place, the nucleotide sequence of the DNA of parent cell changes during meiosis 1 and during meiosis 2, the newly formed daughter cells contains haploid set of the mutated DNA. Hence the nucleotide sequence of the daughter cells are different from that of the parent cells.

As generally gametes are formed due to meiosis, hence due to the mutation gametes with new nucleotide sequence are formed and hence contributing to greater genetic diversity in the resulting population as compare to the normal case i.e.. if there will be no mutation the genetic diversity will be lesser than the mutated condition.

As summary we can say that, the nucleotide sequence of the 4 resulting haploid cells after the meiosis 2 division will be totally different form that of the parent cell. While the resulting haploid cells of meiosis shares same nucleotide sequence with the parent cell in general case.

As mutation causes addition/ deletion/ substitution of the DNA nucleotide sequence, so mutation may also causes improper crossing during meiosis. As a result the length of chromosome formed from crossing over will be unequal and all the daughter cells after meiosis 2 will not get chromosomes of same length.