Cellular Biology

Meiosis necessary for Reproduction



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 MEISOSIS is how sperm and eggs sex cells are made (well, and spores for plants but that is actually more of a birds and bees thing) meiosis, then, is quite necessary for the perpetuation of a species. (A quick note: differentiate meiosis from mitosis. Though similar in that both involve cells splitting, mitosis produces two of the same cell whereas meiosis produces four distinct cells with half the material.)

Meiosis is a process that produces cells with half the number of chromosomes (genetic material) as the original cell.  Four cells containing half the chromosomes, cells in a HAPLOID state, are produced for every single original DIPLOID (complete chromosome material) cell in the process of meiosis.  These four haploid cells are called GAMETES (sperm and eggs) used in sexual reproduction.  Females are born with a lifetime supply of eggs released one at a time after puberty; males continuously produce them after puberty.   

The process of meiosis occurs in two stages each with its own set of phases.  In the first stage of meiosis the following phases occur: Interphase, Prophase, Metaphase, Anaphase, and Telophase.

INTERPHASE is when the chromosomes duplicate; in other words, DNA replication.

PROPHASE is when the portions of the chromosomes carry out synapsis (pair off), later in this phase they exchange genetic material. 

METAPHASE is the point at which the chromosomes randomize material and migrate to the center of the cell, aligning so that the genetic material has half on one side and the other half on the other side..  The chromosomes are like X’s so that if a line is drawn down the center of the X, that is how the chromosomes trail their parts along the equator of the cell.

ANAPHASE is when the now distinct haploids  gravitate toward the polar ends readying for separation.

TELOPHASE is when the cell splits into two.

A second stage of meiosis then occurs with each of the two new cells, so then there is a Prophase II, Metaphase II, Anaphase II, and Telophase II.  This means that for every one starting body cell, four gametes will be produced.  This has also been described as for every one parent cell comes four daughter cells.

Meiosis is a very important step in the grand scheme of procreation.  It is where the two halves of a two individuals become a whole individual.  Is it any wonder people seem to always be seeking out another half?

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