Answer
Mitosis is somatic cell division. It is the process by which normal body cells multiply while keeping the characteristics and genetic combination of daughter cells the same as those of the mother cells. In this process one cell gives rise to two in which the amount of DNA and the number and types of chromosomes are the same as that of the original cell. This is the process by which the human body organizes tissues. grows, and develops. Mitosis process maintains the identity of cells of an organism , assures species continuation, and obviates autoimmune reactions/diseases.
Meiosis ( or reproduction division) is cell division in preparation for reproduction. It is really a combination of two sets of divisions, namely, Meiosis 1(reduction) and Meiosis 2(mitotic). It is called the reduction division because in the first meiotic division( Meiosis 1), the diploid number of chromosomes is halved; consequently,the two cells at the end of Meiosis 1 have only half the number of chromosomes ( the haploid number) of the original cell. Meiosis 2 is similar to mitosis , but since this starts with two haploid cells, the final four products or gem cells that result are all haploid cells with only half the number of chromosomes of the original cells that started meiosis 1.
Work Step by Step
Meiosis is very important for two reasons. First, in species that engage in sexual reproduction , the offspring develops from a zygote; this zygote is a combination of a gamete from the paternal parent ( sperm, and a gamete from the maternal parent(an ovum): if the gametes had the normal somatic number of chromosomes, the human zygote would end up with 92 chromosomes. Such a zygote would probably not survive and grow, and if it did, it would not become a human being because by definition all humans have 23 pairs of chromosomes(46). Second, is the issue of genetic and consequent phenotypic variability of humans. Something unusual happens in Prophase 1 of meiosis: the homologous chromosomes each forms two chromatids, which attach or make contact at different points.. This process is called synapsis, the most important aspect of which is that non-sister chromatids synapse. At Metaphase 1 the tetrads ( bifid chromosomes) line up on the metaphase plate where they are connected by kinetchores to spindle fibres . When separation takes place at Anaphase 1 each member of a pair of homologous chromosomes ( two chromatids) goes to a different "daughter" cell. This assures that the chromosome number is halved. But the genetic composition of each chromosome has changed, for at Anaphase 1, non-sister chromatids have exchanged sequences of genes by the crossing over of sections. This means that the haploid cells that separate at Telophase 1 and start Prophase 2, are different genetically from each other, and from the original cell that started Prophase 1. The genetic differences produced by this process provide the bases for evolution and phenotypic variations in humans.
