2.1 producing new cells

• diploid


  cell that contains 2 sets of chromosomes - the normal number of chromosomes in a cell (in humans we have 23 pairs/46 chromosomes) - each parent contributes 1 chromosome to each pair
• haploid


  cell that contains a single set of chromosomes
• mitosis


  cell division, where parent cell splits to form 2 identical daughter cells
• mitosis is used for


  growth, repair of damaged cells, replacement of damaged tissues, maintaining the diploid chromosome complement (normal # of chromosomes)
• stage 1/6 mitosis

  chromosomes duplicate
• stage 2/6 mitosis

  chromosomes attach to spindle fibres
• stage 3/6 mitosis

  chromosomes line up along the equator of the cell
• stage 4/6 mitosis

  spindle fibres shorten and pull chromatids apart to opposite poles
• stage 5/6 mitosis

  cytoplasm divides
• stage 6/6 mitosis

  2 identical cells formed
• chromatids


  strands of duplicated chromosome
• chromosome


  pair of chromatids
• equator


  the middle of the cell where chromosomes line up
• spindle fibres


  protein structures where chromosomes attach to, they pull chromatids apart to the poles
• stem cells


  unspecialised cells which can divide to self-renew, can become different types of cells, involved in growth and repair, found in embryo at an early stage
• tissue cells


  found in body throughout life
• specialisation of cells becomes


  variety of tissues and organs
• organ system hierarchy


  cells -> tissues -> organs -> systems