Editing Cell growth (section)

===Comparison of the three types of cell division===
The DNA content of a cell is duplicated at the start of the cell reproduction process. Prior to [[DNA replication]], the DNA content of a cell can be represented as the amount Z (the cell has Z chromosomes). After the DNA replication process, the amount of DNA in the cell is 2Z (multiplication: 2 x Z = 2Z). During Binary fission and mitosis the duplicated DNA content of the reproducing parental cell is separated into two equal halves that are destined to end up in the two daughter cells. The final part of the cell reproduction process is [[cell division]], when daughter cells physically split apart from a parental cell. During meiosis, there are two cell division steps that together produce the four daughter cells.

After the completion of binary fission or cell reproduction involving mitosis, each daughter cell has the same amount of DNA (Z) as what the parental cell had before it replicated its DNA. These two types of cell reproduction produced two daughter cells that have the same number of chromosomes as the parental cell. Chromosomes duplicate prior to cell division when forming new skin cells for reproduction. After meiotic cell reproduction the four daughter cells have half the number of chromosomes that the parental cell originally had. This is the [[haploid]] amount of DNA, often symbolized as N. Meiosis is used by [[diploid]] organisms to produce haploid gametes. In a diploid organism such as the human organism, most cells of the body have the diploid amount of DNA, 2N. Using this notation for counting chromosomes we say that human [[Somatic (biology)|somatic]] cells have [[Karyotype|46 chromosomes]] (2N = 46) while human [[Spermatozoon|sperm]] and [[Ovum|egg]]s have 23 chromosomes (N = 23). Humans have 23 distinct types of chromosomes, the 22 [[autosome]]s and the special category of [[Sex-determination system|sex chromosomes]]. There are two distinct sex chromosomes, the X chromosome and the Y chromosome. A diploid human cell has 23 chromosomes from that person's father and 23 from the mother. That is, your body has two copies of human chromosome number 2, one from each of your parents.
[[File:Single and double chromosomes.png|thumb|right|150px|Chromosomes]]
Immediately after DNA replication a human cell will have 46 "double chromosomes". In each double chromosome there are two copies of that chromosome's DNA molecule. During mitosis the double chromosomes are split to produce 92 "single chromosomes", half of which go into each daughter cell. During meiosis, there are two chromosome separation steps which assure that each of the four daughter cells gets one copy of each of the 23 types of chromosome.