cell division

cell division

1. chromosomes

   • in nucleus of cell
   • made of DNA
   • carries genes
     • contain code for making proteins
   • found in pairs, 1from each parent
   • humans have 23 pairs

2. cell cycle

   • mitosis
     • become 2 identical cells
     • before, needs to increase number of subcellular strucutres
     • DNA replicates
     • 1. 1 set of chromosomes pulled to each end
     • 2. nucleus divides
     • 3. cytoplasm & cell membrane divide
     • new cells for growth, repair & asexual reperoduction

3. stem cells

   • unspecialised
   • found in human embryos, umbilical cord, some organs & tissues
   • embryonic stem cells
     • human embryos
     • can make any cell
   • adult stem cells
     • some organs and tissues eg bone marrow
     • only make certain cells
     • limited capacity to divide
   • uses
     • therapeutic cloning
       • stem cells from cloned embryo
       • no rejection
       • objections
         • ethical
         • religious
         • risk of viral infection transfer
     • treating conditions where cells don't work
       • diabetes, paralysis...
   • plants
     • found in meristems
     • can clone plants
       • rare species can be cloned
       • special features can be cloned