MEIOSIS: OUR LIFE MECHANISM
Genetics, GB 425
ABSTRACT. Meiosis is the cell duplication that eukaryotic organisms undergo for reproduction. This form of division facilitates sexual reproduction. If eukaryotes reproduced through mitosis, they would be clones of their family line and unable to reproduce sexually. If they reproduced sexually using meiosis, Every future generation would be polyploidy organisms where chromosomes increase with each generation. Polyploidy conditions are usually fatal to most animals. The stages of meiosis start with prophase I, which is the set up phase before meiosis actually begins. Prophase one is split into a G1, S, and G2 phase. The DNA in the cell replicates and the cell grows. The cell then goes to meiosis I, the chromosomes are split and two haploid cells are the result. Both haploid cells then go through meiosis II, where the chromatids split and are seen as individual chromosomes. The result is four cells with half the chromosomes as the original cell. In animals, males and females go through meiosis slightly differently. The male produces spermatogonia that go through mitosis to make more diploid spermatagonia. Some go through meiosis to make four spermatids. The female goes through the same process, only the cells that go through meiosis have unequal splittings, resulting in only one ovum produced instead of four. Problems in meiosis can cause chromosome mutations such as deletions, inversions, translocations, aneuploidy, and polyploidy. Some are lethal depending on which chromosome is affected or where the mutation occurs on a chromosome.
INTRODUCTION. In reproduction, meiosis and mitosis are very similar as far as what happens in each individual phase of both processes. Meiosis, however, is what separates eukaryotic reproduction from prokaryotic reproduction. Whereas mitosis ends up with two cells identical to the original, meiosis ends with four cells with half as many chromosomes as the...