BIOLOGY, TOPIC 1- CELL BIOLOGY

• What are eukaryotic cells?

  Complex and include all animal and plant cells.
• What are prokaryotic cells?


  Smaller, simpler, single celled organisms. Don't contain nucleus
• What are the different parts of a cell called?

  Subcellular organisms.
• What do the structures of an animal cell do?

  Nucleus- contains genetic information and controls activities of the cell. Cytoplasm- most of chemical reactions take place. Contain enzymes. Cell membrane- holds cell together and controls what goes in and out of the cell Mitochondria- most of reactions for aerobic respiration happens. Respiration transfers energy the cell needs to work. Ribosomes- where proteins are made.
• What do the structures of a plant cell do?


  Rigid cell wall- supports and strengthens the cell.

  Permanent vacuole- contains cell sap.

  Chloroplasts- where photosynthesis occurs, contains chlorophyll which absorbs light for photosynthesis.
• What type of cells are bacterial cells?

  Prokaryotic cells.
• What structure does bacteria have?


  Cell membrane, cell wall, cytoplasm.

  Don't have a nucleus but instead a single circular strand of DNA that freely floats in cytoplasm, also contain small rings of DNA called plasmids.
• How do light microscopes work?

  Use light and lenses to form an image of a specimen and magnify it.
• How do electron microscopes work?


  Use electrons instead of light. Higher magnification than a light microscopes. Also have a higher resolution.
• What is resolution?

  The ability to distinguish between two points
• What is the equation for magnification?


  Magnification=image size/ actual size
• PRACTICAL

  Prepare the slide to view onion cells.

  1. Add a drop of water to the middle of a clean slide.
  2. Cut up an onion and separate into layers. Using tweezers peel from bottom of one of the layers.
  3. Using tweezers, place epidermal tissue into water on the slide.
  4. Add a drop of iodine solution.
  5. Place a cover slip on too. Stand the cover slip upright on slide next to water. Carefully, lift and lower it covering the specimen.
  6. Try not to get air bubbles as they abstruct view of the specimen.
• PRACTICAL

  Use a light microscope to view the slide.

  1. Clip the slide onto the stage.
  2. Select the lowest powered objective lens.
  3. Using the coarse adjustment knob move the stage up to just below objective lens.
  4. Look down eyepiece. Use coarse adjustment knob to move stage downwards until image is roughly in focus.
  5. Use the fine adjustment knob to get clear image of the slide.
  6. If you need a greater magnification, swap to a higher powered objective lens.