Biology p1 cell biology

• Animal cells size


  0.01 mm-0.05mm
• Plant cell size


  0.01mm and 0.10mm
• Magnification of the microscope


  Magnification of eyepiece x Magnification of the object
• Magnification of image


  Size of the image / Actual size of the object
• The best unit for measuring cells is in micrometers, symbol μm
• For sub-cellular structures its best to use nanometres, symbol nm
• 1 mm = 1000 μm
• 100 mm = 100 x 1000 μm = 100 000 μm
• A millimeter is 1/1000 of a meter
• A micrometre is 1/1000 of a millimeter
• A nanometre is 1/1000 of a micrometre
• Cytoplasm


  Jelly-like substance that contains dissolved substances, salts and structures called organelles, it is where many of the chemical reactions happen
• Nucleus


  Contains genetic material including DNA, controlling the cells activities
• Cell membrane


  Structure is permeable to some but not others, it therefore controls the substances in and out of the cell
• Ribosomes


  Tiny structures where protein synthesis occurs
• Mitochondria


  Organelles that contain the enzymes for respiration, and where most energy is released in respiration
• Chloroplasts


  Organelles which contain the green pigment, chlorophyll, absorb light energy for photosynthesis, contains enzymes needed for photosynthesis
• Permanent vacuole


  Filled with sap to help keep the cell turgid
• Cell wall


  Made from cellulose fibers, strengthens the cell and supports the plant
• Prokaryotic cell


  A bacteria cell
• Eukaryotic cell


  A plant or animal cell
• Prokaryotic cells size


  0.02 μm and 2.0 μm
• Types of cell transport

  • Diffusion
  • Osmosis
  • Active transport
• Passive transport


  Energy is not needed as it happens naturally
• Active transport


  Energy is needed
• Diffusion


  The spreading of particles from an area of high concentration to an area of low concentration, down a concentration gradient, passive process
• Osmosis


  The net movement of water particles from an area of high concentration to an area of low concentration, down a concentration gradient, through a partially permeable membrane
• Active transport


  The net movement of particles from a low concentration to a high concentration, against a concentration gradient, uses energy
• Factors affecting cell transport


  • Surface area
  • Temperature
  • Short diffusion pathway
  • Good blood supply
  • Constant concentration gradient
  • Steepness of the concentration gradient