Mitosis, chromosomes + cell cycle

• 3 reasons why new cells are needed:

  growth development repair
• what are the stages of the cell cycle?

  growth, DNA replication & Mitosis , cytokinesis (division)
• what happens when a cell divides?

  Before a cell can divide it needs to grow and increase the number of sub-cellular structures such as ribosomes and mitochondria. The DNA replicates to form two copies of each chromosome.
• why does the DNA replicate/duplicates?

  so 2 new cells will each have a full set of DNA
• Normal amount of chromosomes in 1 person?

  Human cells have 23 pairs of chromosomes, so 46 chromosomes in total.
• what happens when a cell prepares for division?

  its DNA condenses into chromosomes
• what are chromosomes?

  coiled strands of relatively long DNA
• what does the DNA in chromosomes contains?

  a large number of genes which control the development of different characteristics e.g. eye colour
• what is prophase?

  DNA divides
• metaphase?

  chromosomes line up in the centre of the cell
• anaphase?


  1 set of chromosomes is pulled to opposite end of the cell and nucleus divides
• telophase?

  nucleus forms around 2 groups of chromosomes
• cytokinesis? ?

  cytoplasm and cell membrane divide to form 2 identical daughter cells
• step 1 of cell cycle = growth?


  the cell gets larger and produces more sub-cellular structures, such as mitochondria and ribosomes.
• step 2 of cell cycle= DNA replication?


  chromosomes duplicate, so that each consists of 2 copies
• step 3 of cell cycle?


  more cell growth
• step 5 of cell cycle = cytokinesis?

  cytokinesis where the cell membrane and cytoplasm divides into 2