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• Microscopy


  The study of small objects using a microscope
• Types of microscopes


  • Light microscope
  • Electron microscope
• Light microscope


  • First developed in the mid 17th century
  • Uses light to form an image
  • Can be used to view live specimens
  • Relatively cheap and easy to use
  • Magnification up to 2,000 times
• Resolution


  The ability to see two things as separate objects
• Light microscope


  • Low resolution with a resolving power of around 200 nanometers
• Electron microscope


  • Developed by scientists in the 1930s
  • Uses electrons to form an image
  • Specimens must be dead
  • Very expensive and has many conditions
  • Magnification up to 2 million times
  • High resolution of 0.2 nanometers
• The electron microscope is much better than the light microscope in terms of magnification and resolution
• The high magnification and resolution of the electron microscope allows scientists to see and understand lots more about the subcellular structures of cells
• Animal cell


  Contains the following organelles: nucleus, cell membrane, cytoplasm, mitochondria, ribosomes
• Nucleus


  Controls the cell's activities and contains genetic material (DNA)
• Cell membrane


  Responsible for controlling the passage of substances in and out of the cell
• Cytoplasm


  Liquid gel that fills the entire cell and is where chemical reactions occur
• Mitochondria


  Where aerobic respiration occurs to release energy for the cell
• Ribosomes


  Site of protein synthesis
• Plant cell


  • Contains the following organelles in addition to those in animal cells: chloroplasts, permanent vacuole, cell wall
• Chloroplasts


  Contain chlorophyll and are the site of photosynthesis
• Permanent vacuole


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


  Made of cellulose, strengthens and supports the plant cell
• It is important to learn the differences between plant and animal cells
• Eukaryotic cells


  Have a cell membrane, cytoplasm, and genetic material enclosed in a nucleus
• Prokaryotic cells


  Lack a true nucleus, have genetic material as a single loop of DNA in the cytoplasm, may have plasmids and a cell wall, but lack organelles like mitochondria and chloroplasts
• Prokaryotic cells are found in bacteria
• Cell differentiation


  The process by which cells develop different subcellular structures to carry out specialized functions
• Specialized animal cells


  • Sperm cell
  • Muscle cell
  • Nerve cell
• Sperm cell


  • Has a tail to help it swim, a midpiece with many mitochondria to provide energy, an acrosome with enzymes to break down the egg, and a large nucleus to contain DNA
• Muscle cell


  • Has many mitochondria to release energy for contraction, special proteins that cause contraction by sliding, and can store glycogen
• Nerve cell


  • Has a long axon to carry electrical impulses, dendrites to connect to other nerve cells, and nerve endings that release chemical messengers
• Specialized plant cells


  • Root hair cell
  • Xylem cell
  • Phloem cell
• Root hair cell


  • Has a large surface area for absorption, a large permanent vacuole to speed up osmosis, and many mitochondria for active transport of mineral ions
• Xylem cell


  • Forms long hollow tubes with spirals of lignin to allow easy movement of water and minerals, and to provide structural support
• Phloem cell


  • Has sieve plates with holes to allow easy movement of dissolved food, and companion cells with many mitochondria to provide energy for the transport
• Diffusion


  The spreading out of particles in a solution or gas from an area of higher concentration to an area of lower concentration
• Diffusion is a passive process that does not require additional energy
• Factors affecting rate of diffusion

  • Temperature (higher temperature increases rate)
  • Concentration gradient (steeper gradient increases rate)
  • Surface area (larger surface area increases rate)
• Osmosis


  The diffusion of water molecules from a dilute solution to a more concentrated solution through a partially permeable membrane
• Osmosis is a passive process that occurs down a concentration gradient
• Osmosis is important in animal cells to maintain the right internal environment and solute concentrations
• Left side of the membrane

  Has more water molecules
• Right side of the membrane

  Has less water molecules and more sucrose or solute molecules, therefore it is the concentrated side
• Osmosis


  1. Occurs down a concentration gradient or from a dilute solution to a more concentrated solution

  2. Net movement of water is from the left side to the right side

  3. Eventually the water concentration will be equal on both sides

  4. Water molecules will continue to move back and forth across the partially permeable membrane but there's no further net movement of water, the water is balanced on both sides