Topic 1 cell biology

• The topic is cell biology
• Animal and plant cells are called eukaryotic cells
• Similarities between animal and plant cells

  • Cell membrane
  • Mitochondria
  • Ribosomes
  • Cytoplasm
  • Nucleus
• Additional structures in plant cells

  • Permanent vacuole
  • Chloroplasts
  • Cell wall
• Bacteria cells are called prokaryotic cells
• Prokaryotic cells


  • Do not contain nuclei
  • Are much smaller than eukaryotic cells
  • Do not contain mitochondria or ribosomes
  • Do not contain chloroplasts or vacuoles
  • Are single-celled organisms
• Prokaryotic cells have a single DNA loop and free-flowing plasmids in the cytoplasm instead of a nucleus
• Differences between light and electron microscopes

  • Light microscope is cheaper, easier to use and set up
  • Electron microscope has better magnification and resolution, but requires dead specimens
• The equation linking magnification, image size and actual size is: Magnification = Image size ÷ Actual size Image size = magnification x actual size.
• Cell specialization


  The process by which cells differentiate to become specialized for a certain function
• Types of stem cells

  • Embryonic (totipotent)
  • Adult (multipotent)
• Mitosis and the cell cycle

  1. DNA duplicates

  2. Chromosomes line up in the center

  3. Fibers pull chromosomes to each side

  4. Nuclei reform

  5. Cell membrane splits to form two daughter cells
• Diffusion


  Passive movement of particles from high to low concentration
• Osmosis


  Passive movement of water particles through a partially permeable membrane from low to high concentration
• Active transport


  Net movement of particles from low to high concentration, requiring energy
• Examples of diffusion and osmosis in the body

  • Gas exchange in lungs (diffusion)
  • Water absorption in large intestine (osmosis)
• Factors affecting cell transport

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