mitosis

• interphase comes before mitosis in the cell cycle - its when cells grow and replicate their DNA ready for division
• interphase - the cell carries out normal functions, also prepares to divide

  • DNA is unravelled and replicated, to double its genetic content
  • organelles also replicated so it has spare
  • ATP Content is increased
• 1. PROPHASE - chromosomes condense and get shorter and fatter

  • centrioles move to opposite ends of the cells forming a network of protein fibres across called the spindle
  • the nuclear envelope breaks down and chromosomes lie free int he cytoplasm.
• 2. METAPHASE

  • The chromosomes line up along the middle of the cell and become attached to the spindle by their centromere
  • at the metaphase checkpoint, the cell checks all chromosomes are attached to the spindle before mitosis can continue
• 3) ANAPHASE

  • Centromeres divide, separating each pair of of sister chromatids.
  • spindles contract, pulling chromatids to opposite ends of the cell, centromere first
• 4) TELOPHASE

  • Chromatids reach opposite poles on the spindle
  • they uncoil and become long and thin again
  • now called chromosomes
  • nuclear envelope forms around each group of chromosomes so there are now 2 nuclei
• cytokinesis -

  • cytoplasm divides
  • in animal cells, a cleavage furrow form to divide the cell membranes
  • now 2 identical daughter cells genetically identical to the original to the cell
  • cytokinesis begins in anaphase and ends in telophase
  • separate process to mitosis