Mitosis

• Chromosomes

  • Found in nucleus
  • Made up of DNA
  • Body cells contain two of each chromosome (paired)
  • Human body cells contain 23 pairs (46 chromosomes)
  • Gametes have unpaired chromosomes (e.g. human gametes have only 23 single chromosomes)
  • Chromosomes carry a large number of genes
• Cell cycle

  • First stage: DNA replicates to form two copies of each chromosome, cell also grows and copies internal structures (mitochondria etc.)
  • Second stage: Mitosis takes place, one set of chromosomes is pulled to the poles of the cell, nucleus also divides
  • Third stage: Cytoplasm and cell membrane divide to form two identical cells
• Functions of mitosis

  1. Essential for growth and development of multicellular organisms (eg. plants and animals)
  2. Takes place when an organism repairs itself (when a broken bone heals)
  3. Happens during asexual reproduction