• There are three primary processes in which cells replicate; prokaryotic cells through binary fission, eukaryotic cells through mitosis and eukaryotic gametes through meiosis.

• Occurs in prokaryotic cells, usually bacteria.
• Begins with one cell (containing circular DNA)
• DNA replication occurs prior to binary fission
  Steps of Binary Fission

1. DNA 'condensates' to form identical circular chromosomes.
2. Chromosomes attach to the interior of the membrane.
3. As the cell begins to form cleavage, the two chromosomes are drawn to opposite ends of the cell.
4. The cell membrane 'pinches' off the cleavage, forming two new cells.

Advantages

• Requires only one parent cell
• Extremely fast (division can happen as quickly as in 20 minutes)

Disadvantages

• Reduces genetic diversity, as all daughter cells are exactly identical to the parent cells (and no deliberate genetic recombination - as in meiosis - occurs)

• Occurs in prokaryotic cells, such as human and plant cells.
• Prior to mitosis, a stage called 'interphase' involves replication of the DNA (chromosomes) and 'growth checkpoints' that the cell needs to pass in order to continue on to mitosis without errors.
• Chromosomes consist of pairs of identical chromatids joined by a round centromere.

Steps of Mitosis

1. Prophase:: Nuclear membrane breaks down and chromosomes condense, enabling them to become visible under a microscope. Spindle fibres gradually form.
2. Metaphase:: Chromatid pairs are oriented in the centre (along the 'metaphase' plate) by spindle fibres.
3. Anaphase:: Chromatid pairs are separated to each pole by the spindle fibres to form two identical sets of daughter chromosomes.
4. Telophase:: Spindle fibres break down, chromosomes decondense. Cleavage furrow forms.