Mitosis

• DNA condenses to form chromosomes.

  Chromosomes line up along the centre of the cells.

  Cell fibres pull the two arms of each chromosome to opposite sides (poles) of the cell.

  Cytokinesis - the entire cell divides to form two identical daughter cells.
• Multicellular organisms, like ourselves, require a continuous supply of new cells. 

  What are the three reasons why new cells are required?

  Growth (we need more cells as we grow)

  Repair (we need to replace the cells that we lose each day)
• What is the cell cycle?

  The series of steps that take place as a cell grows and then divides 
• 1. Cellular growth - the cell gets larger and produces more sub-cellular structures, such as mitochondria and ribosomes. 
  2. DNA replication - chromosomes duplicate, so that each consists of two arms (copies).
  3. More cell growth.
  4. Mitosis - the DNA divides into two.
  5. Cytokinesis - the cell divides into two.
• How many pairs of chromosomes do most human cells have?

  23
• Are the cells created by mitosis genetically identical to each other, or genetically different? 

  Genetically identical 
• When a cell divides by mitosis, how many cells are produced? 

  2
• What do we commonly call the cells produced by mitosis? 

  daughter cells