the cell cycle

• The Cell Cycle

  1. Growth and DNA replication
  2. mitosis (nucleus divides)
  3. cell divides
• DNA Replication

  1. the dna unzips forming 2 seperate strands
  2. bases are exposed
  3. free dna nucelotides pair up with their complemetary base pairs
  4. new backbones form producing 2 identical chromosomes.
• Mitosis

  1. chromosomes line up in the centre of the cell.
  2. exact copies seperate and move to opposite ends of the cell, being pulled by spindle fibres
  3. two nuclei form containing a full set of identical chromsomes.
• Growth

  BEFORE DNA replication, the number of sub-cellular structures (such as mitochondria and ribosomes) needs to increase.
• Cell divides

  the cytoplasm and cell membranes split, forming two identical daughter cells.
• Why do we need cell division (by mitosis)?

  • important in their growth and development
  • replacing damaged cells.
  • vital part of asexual reproduction