Mitosis

• In mitosis, the chromosomes of a cell are duplicated and the genetic information is then equally shared between the two daughter cells.
• The events of mitosis are continuous, there is a sequence of events (phases) that are known as prophase, metaphase, anaphase and telophase.
• Mitosis is the process by which a cell divides to produce two genetically identical daughter cells
• Before mitosis begins, the genetic material replicates to produce exact copies of the original chromosomes. By the beginning of prophase, both the originals and the copies are referred to chromatids. In prophase, the chromosomes consists of two daughter chromatids that are attached to each other at a region known as the centromere. The nucleus breaks down and the centrioles begin to pull apart from the spindle.
• The nuclear membrane has broken down and the centrioles have moved to opposite poles of the cell. In moving apart, the centrioles have formed between them a set of microtublee that is known as a spindle. The chromatids appear to compete for position on the metaphase plate (equator) of the spindle during metaphase.
• In anaphase, the centromeres split so that the two identical linked chromatids become separate entities. The chromatids from each pair are pulled, centromere first, towards opposite poles of the cell. At the end of anaphase, the two sets of chromatids have been separated to opposite ends of the cell. The chromatids cannot move on their own, they rely on the microtubules of the spindle to move them. The spindle consists of overlapping microtubules containing contractile fibres that contract and cause the movement of the chromatids
• During telophase, the spindle fibres break down and nuclear envelopes form around the two sets of chromosomes. The nuclei and centrioles are also reformed. The chromosomes begin to unravel and separate, become less dense and harder to see
• 1. Prophase
  2. Metaphase
  3. Anaphase
  4. Telophase
  5. Cytokinesis

  
• 1. Early prophase
  2. Late prophase
  3. Metaphase
  4. Early anaphase
  5. Late anaphase
  6. Telophase

  
• Mitosis is how organisms grow and replace new cells. It also the method organisms use for asexual reproduction.
• Asexual reproduction is the production of genetically identical offspring from a single parent cell or organism. It does not rely on finding a mate and can give rise to large numbers of offspring very rapidly. However, because the offspring are mostly genetically identical to the parent organism, a change in environment (e.g change in temperature, human intervention, new disease) could cause total destruction of a group of genetically identical organisms
• The mitotic index is a measure of how actively the cells in a tissue are dividing. It is the ratio between the number of cells in a tissue sample that are in the nucleus and the total number of cells in the sample.

  mitotic index = cells in mitosis/total number of cells