过分不够风格（Too much, no style）.doc

过分不够风格（Too much, no style） Meiosis is a specific division in the process of forming a generative cell in sexually transmitted individuals Different from mitosis and amitosis, meiosis occurs only in the life cycle of a certain stage, it is a special way of splitting process of sexual reproduction of the biological maturation, gamete formation in. In the process of meiosis chromosome copy only once, continuous cell division two times, two times will be split evenly among homologous chromosomes and sister chromosome sub cells, make the final formation of gametes chromosome chromosome is only half of the mother cell. When fertilized, the male and female gametes combine to restore the number of parental chromosomes, thus maintaining the constancy of the number of chromosomes in the species. The exchange of homologous chromosomes during meiosis, the genetic diversity of gametes, increased offspring adaptability, so meiosis is not only the guarantee mechanism of biological stable chromosome number, and is also the same species to adapt to environmental changes evolving mechanism. Meiosis is not only to maintain a stable species genetic material transfer means; in the process of meiosis by crossover of homologous chromosomes, chromosome fragment exchange non sister free combination of non homologous chromosomes and four points in the body, increase the gene variant, increase the genetic diversity, provide more original material for natural selection...... Edit the main type of this paragraph Summary Meiosis (Meiosis) is characterized by a DNA replication and cell division, continuous two times, the formation of haploid sperm and eggs (Figure 13-12), the fertilization and recovery of diploid chromosomes exchange homologous during meiosis, and four in non sister chromatid exchange fragment of monomer. The genetic diversity of gametes, increase in figure 13-12 (1) offspring adaptability, therefore meiosis is not only the guarantee mechanism of biological stable chromosome numb