Cell Division
Mitosis - The cellular division where one original cell replicates its genetic material as well as structure to result in two identical daughter cells. The steps of Mitosis include:

Interphase: The period between the previous cell division where the parent cell must grow, in order to be able to divide again. The DNA (chromosomes) must also be replicated to a diploid (2N) stage. The DNA has been replicated but is not condensed (they are chromatin instead of chromosomes).
Prophase: Chromatin shortens and condenses until they are in the chromosome form. The nuclear membrane is no longer visible. The centrioles beging to become visible placing themselves at the poles of the nucleus.
Metaphase: Spindle fibres attach themselves to the chromosome pairs and line themselves in the middle of the nucleus (equatorial plate).
Anaphase: Spindle fibres shorten and the chromatids separate, pulled by the centrioles.
Telophase: The chromatids reach the poles of their respective spindles. The spindle fibres then distintegrate once a nuclear membrane has formed around the chromatids.
Cytokinesis: The process of splitting the daughter cells. Each daughter cell contains the same number and quality of chromosomes (assuming no mutations).

Meiosis - The cellular division where one original cell undergoes a repitition of mitosis, followed immediately by another lot of mitosis which does NOT replicate the chromosomes, resulting in four haploid (N) cells. With relation to the human system, this differs slightly. The steps of meiosis are:

Prophase I: DNA coils tightly and individual chromosomes begin to become visible. Homologous chromosome (about the same length and size) match up together and intertwine, resulting in crossing over of DNA.
Metaphase I: The nuclear membrane has disappeared and the centrioles begin moving towards the poles. Each pair of chromosomes lines up on the metaphase plate (equatorial).
Anaphase I: The centrioles use the spindle fibres to pull chromosomes towards the specific poles.
Telophase I: The nuclear membrane reforms around the daughter nuclei. The two cells split.
Prophase II: The nuclear membrane immediately breaks down.
Metaphase II: Centrioles work at the poles to create spindle fibres to separate the chromosomes.
Anaphase II: Spindle fibres pull one of the pair (lined up on the plate) towards its specific pole.
Telophase II: The nuclear membrane forms around the daughter chromosomes, and the cells are then separated.

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Biology Note on Study Notes - Term 4 Biology, created by maddie.rapisardi on 19/11/2013.

Study Notes - Term 4 Biology