What's the difference between mitosis and meiosis?
Mitosis is cell division of a diploid cell resulting in two identical diploid daughter cells. The chromosomes are replicated before mitosis begins during the S phase of interphase. This ensures a complete set of chromosomes will be distributed to each daughter cell at the end of cell division.
The steps of mitosis are prophase, metaphase, anaphase and telophase, followed by cytoplasmic division--cytokinesis. At the end of this process, the resulting daughter cells will be smaller than the parent cell but genetically identical.
Meiosis is known as a reduction division. It is a special type of cell division that occurs in the gonads-female ovaries or male testes. These are sex organs that produce haploid gametes known as sperm or eggs.
A germ cell in the gonads contains the diploid amount of chromosomes for that species. Replication of the chromosomes occurs before meiosis begins. There are two rounds of cell division--meiosis I and meiosis II. The same steps are followed as in mitosis-prophase, metaphase, anaphase and telophase for two rounds of cell division.
In prophase I, the chromosomes form homologous pairs in groups of four known as tetrads. Crossing over occurs between non-sister chromosomes. This is an exchange of genetic material and is like shuffling the genes resulting in great variation in the gametes that will form later. The end result of meiosis is four haploid cells--four sperms in males or one egg and three polar bodies in females.
Meiotic cell division produces haploid gametes and when two gametes fuse together during fertilization, the resulting zygote will have the diploid amount of chromosomes once again.