Biology notes on genetics.

A bacterium is a single, prokaryotic cell. It has a cell wall but lacks a nucleus and membrane - bound organelles. A bacterium's single DNA molecule is not coiled around proteins to form chromosomes. Instead, its face of the plasma membrane like a rope attached to the inner wall of a tent. First the DNA is copied, and then the cell splits. Before a bacterium can divide it must have two copies of its DNA …

…is identical to mitosis except that the chromosomes do not replicate before they divide at their centromeres. In anaphase II the centromeres divide, and the chromatids, now called chromosomes, move to opposite poles of the cell. Meiosis II is followed by cytokinesis, in which new membranes are formed around the four products of meiosis to create four haploid cells. Crossing-over is an efficient way to produce genetic recombination, the formation of new combinations of genes.