Meiosis involves the formation of gametes or sex cells. Sex cells are sperm and egg cells. If you remember, sperm and eggs cells fuse together to form a zygote that will eventually diffentiate and divide to form a baby.
*Don't meiosis confused with mitosis because they are two totally separate processes! Meiosis only occurs in sex cells and mitosis occurs in stomatic cells (normal body cells). Mitosis purpose is to make more body cells so that we don't run out of cells! Mitosis creates 2 cells and meiosis creates 4 cells. Also, mitosis creates cells that are diploid (meaning each cell contains 46 chromosomes) and meiosis creates cells that are haploid (meaning each cell contains 23 chromosomes)
IMPORTANT: The primary purpose of mitosis is to create 4 sex cells with half the number of original number of chromosomes (haploid) that are used in the process of reproduction. You get one set of chromosomes from your mother and one set from your father (23 chromosomes from your father+23 chromosome from your mother= 46 chromosome total)
There are 8 steps and 2 phases in meiosis. The steps in the first phase are the same in the second phase. There are 4 steps to remember. The acryomn PMAT (similar to GMAT business school exam) can be used for memorization purposes.
The way I like to teach this concept is by using an analogy of a relationship between a boyfriend and a girlfriend.
The boyfriend and girlfriend are in a relationship they are preparing to live together and have a long happy life together (nucleus is expanding and nuclear membrane is braking down/disappearing). They become interconnected (crossing over/recombination of chromosomes)*and looking foward to their new life together
After sometime, their relationship starts to fall apart because they start to feel like they want to go their separate ways (formation of the microtubules in the centrosome and the microtubles attach to the kinetichore or centromere of homologous chromosomes + chromosomes line up in the middle of the cell called the metaphase plate)
The relationship does not work out so they decided to move out of their home. (pairs of homologous chromosomes are moved to opposite sides the cell with the help of the microtubules)
Their separation is finalized and they want nothing to do with each other anymore. They officially move into their own apartments. (cleavage furrow forms in the middle of the cell allow the cell to divide in half + chromsomes are on opposite poles of the cell). Cytokinesis is the process of dividing into two separate cells.
IMPORTANT: Key components of meiosis are crossing over, two phases, and creation of 4 haploid cells.
Note: At the end of meiosis I, there are 2 pairs of chromatids (2 chromatids= 1 chromosome) in each cell. At the end meiosis II, there is 1 chromatid in each cell.
*Recombination is the process where two homologous chromosomes exchange genetic information with each other. This process is responsible for genetic diversity.