Biology

• Animal cell organelles


  • Cell membrane
  • Cytoplasm
  • Nucleus
  • Ribosomes
  • Mitochondria
• Animal cell organelles


  • Cell structure
  • Function
  • Nucleus - Stores DNA and controls cell function
  • Cytoplasm - Site of chemical reactions
  • Cell membrane - Controls entry and exit of materials
  • Ribosomes - Site of protein synthesis
  • Mitochondria - Site of aerobic respiration
• What to do...


  1. Collect - 1 microscope, 1 slides, 1 cover slips, 1 onion sample(stain to be shared)

  2. Do - Scrape a thin lining of cells from the onion

  3. Spread the cells on the centre of a slide

  4. Add stain to slide (1 drop)

  5. Gently place on cover slip

  6. View under microscope

  7. Sketch what you see in your jotter
• Plant cell organelles


  • Cell membrane
  • Cytoplasm
  • Nucleus
  • Ribosomes
  • Mitochondria
  • Chloroplast
  • Vacuole
  • Cell wall
• Plant cell organelles


  • Cell structure
  • Function
  • Nucleus - Stores DNA and controls cell function
  • Cytoplasm - Site of chemical reactions
  • Cell membrane - Controls entry and exit of materials
  • Ribosomes - Site of protein synthesis
  • Mitochondria - Site of aerobic respiration
  • Vacuole - Stores water and minerals
  • Chloroplasts - Site of photosynthesis
  • Cell wall - Provides support, maintains cell shape
• What to do...


  1. Collect - Bioviewer

  2. Do - Look at samples of yeast and bacterial cells

  3. Make a simple sketch of each in your jotter
• Fungal cell organelles


  • Cytoplasm
  • Nucleus
  • Mitochondria
  • Cell membrane
  • Cell wall
  • Ribosomes
• Bacterial cell organelles


  • Cell wall
  • Cell membrane
  • Large circular DNA
  • Cytoplasm
  • Ribosomes
  • Plasmids
• Red blood cells are animal cells without a nucleus
• Some underground plant cells e.g. roots/onions do not have chloroplasts
• Chloroplasts = stripy ovals, Mitochondria = squiggly ovals
• Plant cell walls are made of cellulose, but fungal and bacterial cell walls are not
• Some bacteria can have a flagellum (tail) to swim
• Organelles common to all cells

  • Cytoplasm
  • Cell membrane
  • Ribosome
• Cell wall is a similarity between plant, fungal and bacterial cells
• Bacteria do not have a nucleus or mitochondria that the other cells do have
• All organisms are made of cells
• Unicellular organisms


  • bacterium
  • amoeba
• Multicellular organisms


  Organisms with more than one cell
• Magnification


  • Cells are too small to be seen individually - so we use a microscope
  • The power of 100x makes 1mm look like 100mm
  • Magnification = eyepiece x objective
• Magnification


  • Eyepiece 10x, Objective 20x = 200x magnification
  • Object 0.1mm, Apparent size 20mm
• Magnification examples


  • Eyepiece 5x, Objective 20x = 100x, Object 0.01mm, Apparent size 1mm
  • Eyepiece 10x, Objective 50x = 500x, Object 0.01mm, Apparent size 5mm
  • Eyepiece 20x, Objective 40x = 800x, Object 0.02mm, Apparent size 16mm
  • Eyepiece 30x, Objective 30x = 900x, Object 0.001mm, Apparent size 0.9mm
  • Eyepiece 40x, Objective 10x = 400x, Object 0.0001mm, Apparent size 0.04mm
• The Microscope


  • Eyepiece - Where you look to see the specimen
  • Fine focus - Makes the image pin sharp
  • Light - To illuminate the specimen
  • Rough focus - To get a clear image to start with
  • Handle - To carry the microscope safely
  • Turret - Rotates to select the magnification
  • Stage - The slide is placed here
  • Clip - Holds the slide in place
  • Objective lenses - Magnify the specimen
• Using the Microscope


  1. Clip the slide on the stage

  2. Swing the low power lens into position

  3. Bring the stage up close to the objective lens with the rough focus

  4. Looking into the eyepiece, adjust the focus by moving the stage slowly downwards

  5. Achieve a perfect image using the fine focus

  6. If you move up in magnification, you may have to re-focus
• What to do...


  1. Collect - 1 microscope, 2 slides, 2 cover slips, 2 cotton buds (stain to be shared)

  2. Do - Swab the inside of your cheek

  3. Spread the cells on the centre of a slide

  4. Dispose of swab in disinfectant

  5. Add stain to slide (1 drop)

  6. Gently place on cover slip

  7. View under microscope

  8. Sketch what you see in your jotter

  9. Dispose of slide in disinfectant
• Average size of cells = total width /number of cells