11. Show by a series of diagrammatic sketches how at the end of meiosis II, four types of gametes are formed with two parental and two new combinations of the alleles of the genes.
Answers
Explanation:
Meiosis is divided into two parts: meiosis I and meiosis II.
In meiosis I, each chromosome in a cell is replicated to yield duplicated sister chromatides for each member of the homologous chromosomes.
Physical contact between chromatids may occur, resulting in the formation of chiasmata (from the Greek khiasma: to cross).
Chiasmata are thought to represent the process of crossing over, or recombination, in which an exchange of DNA between two of the four chromatids occurs.
A chiasma occurs at least once per chromosome pair. Thus, a parental haplotype (the arrangement of many alleles along a chromosome) will not remain intact upon transmission to an offspring but, instead, will become a new combination of the original maternal and paternal haplotypes.
Following the process of crossing over, at least two of the four chromatids become unique, or unlike those of the parent.
The cellular division in meiosis I is called the reduction division because it results in the reduction of the chromosome number from diploid (cell has two copies of each chromosome, one maternal and one paternal chromosome) to haploid (cell has only one copy of each chromosome, either maternally-derived or paternally-derived chromosome). At this stage it is important to remember the remaining chromosomes are comprised of the sister chromatids, which will separate in meiosis 2