Cells

• Cells


  The basic unit of all forms of life
• Structural differences between various types of cells

  • Enable them to perform specific functions within the organism
  • Controlled by genes in the nucleus
• Cell division by mitosis

  1. Produces two new identical cells

  2. Allows organism to grow
• Stem cell technology


  Allows doctors to repair damaged organs by growing new tissue from stem cells
• Main sub-cellular structures


  • Nucleus
  • Cell membranes
  • Mitochondria
  • Chloroplasts in plant cells
  • Plasmids in bacterial cells
• Parts of most animal cells

  • Nucleus
  • Cytoplasm
  • Cell membrane
  • Mitochondria
  • Ribosomes
• Additional parts found in plant cells

  • Chloroplasts
  • Permanent vacuole filled with cell sap
• Plant and algal cells have a cell wall made of cellulose, which strengthens the cell
• Estimations


  Can be used to judge the relative size or area of sub-cellular structures
• Cell specialisation


  • Cells may be specialised to carry out a particular function
  • Animal and plant cells may be specialised to function within a tissue, an organ, organ systems, or whole organisms
• Specialised cells in animals

  • Sperm cells
  • Nerve cells
  • Muscle cells
• Specialised cells in plants

  • Root hair cells
  • Xylem cells
  • Phloem cells
• Eukaryotes and prokaryotes


  Plant and animal cells (eukaryotic cells) have a cell membrane, cytoplasm and genetic material enclosed in a nucleus