mitosis

• mitosis

  = nuclear division

  • ensures both daughter cells produced are genetically identical.
  • for growth, replacement and repair of tissues.
  • necessary for asexual reproduction.
• prophase

  1 chromatin fibres begin to coil and condense to form chromosomes, nuclear membrane breaks down.

  2 protein microtubules form spindle shapes= linking poles of the cell- needed to move chromosomes into correct positions.

  3 centrioles migrate to opposite poles, they're cylindrical bundles, help formation of spindle.

  4 spindle fibres attach to specific areas on centromers and begin to move chromosomes into the middle of the cell.
• metaphase

  1 chromosomes moved by spindle fibres to form plane in centre of the cell= metaphase plate.
• anaphase

  1 centromers holding pairs of chromatids in each chromosome divide, they're separated and pulled to opposite poles of the cell by shortening spindle fibres.
• telophase 


  1 chromatids have reached poles and now called chromosomes.

  -2 new sets of chromosomes assemble at each pole and nuclear envelope forms around them.
• cytokinesis 


  = actual division of the cell into two separate cells, begins during telophase.
• cytokinesis- animal cells


  = a cleavage furrow forms around the middle of the cell.

  • cell-surface membrane pulled inwards by the cytoskeleton until it's close enough to fuse around the middle forming 2 cells.
• cytokinesis- plant cells 


  = have a cell wall so no cleavage furrow formed.

  • vesicles from golgi body begin to assemble in the same place as where metaphase plate is formed.
  • vesicles fuse together and cell-surface membrane, dividing into 2 cells.
  • new sections of the cell wall form along new section of membrane.