B1 Cell Biology Processes

• Binary fission - division of bacteria

  1. Circular DNA and plasmids replicate
  2. The cell grows and circular DNA moves to opposite ends of the cell
  3. The cytoplasm starts to divide and new cell walls form
  4. The cytoplasm divides and 2 daughter cells are produced
  5. Daughter cells have 1 copy of circular DNA, but numerous plasmids
• Mitosis - division of cells

  1. Cell grows and increases its amount of sub-cellular structures
  2. The DNA duplicates
  3. The copied DNA forms X shaped chromosomes
  4. Chromosomes line up at the centre of the cell and cell fibres pull them apart
  5. The 2 arms of the chromosomes go to opposite ends of the cell
  6. Membranes form that act as new nuclei for the cells
  7. The cytoplasm and cell membrane divide and this creates 2 identical daughter cells (same DNA as parents)
• Therapeutic cloning = creating an embryo that has the same genetic material as the patient
• Therapeutic cloning - method

  1. The nucleus is removed from a patients cell and the nucleus from a donor is removed from their egg
  2. The patients nucleus is put into the donor’s empty egg and zapped
  3. The egg and nucleus combine to make an embryo
  4. Embryonic stem cells are taken from the embryo and can be cultured to grow into an organ/ tissue cells