Cell division and cellular organisation

• Describe the process of the cell cycle

  G1 - cell grows new organelles and proteins made

  Checkpoint - checks for DNA damage

  S- cell replicates its DNA

  Checkpoint - checks for DNA damage

  G2- cell keeps growing and proteins need for cell division are made

  M - mitosis and cytokinesis
• what is the importance of mitosis


  needed for growth and repairing damaged tissues
• What are the stages of mitosis?


  The stages of mitosis are prophase, metaphase, anaphase, and telophase
• what happens in prophase?


  Chromosomes condense

  centrioles move to opposite ends of the cell

  nuclear envelope begin to break down
• what happens in metaphase?


  chromosomes line up and are attached to spindle by their centromere
• what happens in anaphase?


  sister chromatids move to opposite ends of the cell
• what happens in telophase?


  Chromatids reach end of opposite poles

  known as chromosomes again

  nuclear envelope reforms

  2 nuclei
• what happens in cytokinesis?


  Occurs between anaphase and telophase

  cytoplasm divides

  (in animals) cleavage of furrows divides the cell membrane

  2 genetically identical daughter cells
• What is meiosis?


  Type of cell division that occurs in reproductive organs to produce gametes
• what happens in prophase one?


  chromosomes condense and arrange in homologous pairs and crossing over occurs

  centrioles move to opposite ends

  nuclear envelope begins to break down
• what happens in metaphase one?


  homologous pairs line up and attach to spindle fibres
• what happens in anaphase one?


  spindles contract separating pairs
• what happens in telophase one?


  nuclear envelope reforms

  cytokinesis occurs

  2 haploid daughter cells produced
• what is the difference between the cells produced in meiosis compared to mitosis?


  the cells produced are all genetically different
• how many haploid cells are produced after meiosis 2


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