The two different types of meiosis, meiosis I and meiosis II, undergo the same interphase. In this phase, the chromosomes replicate like they do in the S-phase preceding mitosis. In prophase I, the homogonous chromosomes, or two sister chromosomes, come together and condense in a process called synapsis. The four chromatids of the pair of homogonous chromosomes visible under a microscope is called a tetrad. Some of these chromosomes crisscross at the chiasmata, a site …showed first 75 words of 502 total…

…showed last 75 words of 502 total…chromosomes become part of the daughter cells, creating variety in genetic traits. Crossing over also creates genetic variety. Each animal produces a collection of gametes that vary greatly from another because of crossing over, the production of individual chromosomes that combine genes inherited from parents. Random fertilization contributes to genetic variation before the zygote forms. The sperm has 8 million possible ovum that it will fertilize, meaning that there are 8 million different combinations of possible offspring.