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• Light or Optical microscopes


  • Poor resolution due to the wavelength of light
  • Can use living samples
  • Can get a color image
• Transmission electron microscopes


  • Much higher magnification and resolution
  • Electrons pass through the specimen to create an image
• Scanning electron microscopes


  • Electrons are bouncing off the surface to create a 3D image
• Laser scanning confocal microscopes

  • High resolution and 3D
  • Uses laser light to create the image
• Resolution


  The minimum distance between two objects in which you can still view them as separate
• Magnification


  How many times larger the image is compared to the actual object
• Slide preparation types


  • Dry mount
  • Wet mount
  • Squash slide
  • Smear slide
• Calibrating the eyepiece graticule

  1. Use a stage micrometer

  2. Align the stage micrometer with the eyepiece graticule

  3. Count how many divisions on the eyepiece graticule fit into one division on the stage micrometer

  4. Calculate the value of one division on the eyepiece graticule
• Magnification calculation


  Size of the image divided by size of the real object
• Staining


  Adds colour to make cell components more visible
• Differential staining


  Uses multiple chemical stains to stain different parts of cells different colours
• Gram staining


  Uses crystal violet and safronin to identify gram-positive and gram-negative bacteria
• Scientific drawings


  Accurate pencil drawings showing size, shape, proportion and labelling of specimens, without shading or colour
• Electron microscopes

  • Use a beam of electrons to create the image
  • Require a vacuum for the specimen
  • Produce black and white images
• Transmission electron microscopes


  • Specimen must be very thin
  • Electrons pass through the specimen to create a 2D image
• Scanning electron microscopes


  Electrons are beamed onto the surface of the specimen to create a 3D image
• Laser scanning confocal microscopes


  Use a focused laser beam to scan the specimen and create a 3D fluorescent image
• Organelles in eukaryotic cells

  • Nucleus
  • Flagella
  • Cilia
  • Centrioles
  • Cytoskeleton
  • Endoplasmic reticulum
  • Golgi apparatus
  • Lysosomes
  • Mitochondria
  • Peroxisomes
  • Plastids
  • Vacuoles
  • Ribosomes
• Nucleus


  Contains the genetic material and is the site of DNA replication and transcription
• Flagella


  Whip-like tail structures for cell mobility and sensing chemical stimuli
• Cilia

  Hair-like projections that can be stationary or mobile to move substances
• Centrioles


  Microtubule structures involved in spindle fibre formation during cell division
• Cytoskeleton


  Network of microfilaments, microtubules and intermediate filaments that provide mechanical strength and stability to the cell
• Endoplasmic reticulum


  Folded membrane system, with rough ER for protein synthesis and smooth ER for lipid and carbohydrate synthesis
• Golgi apparatus


  Processes, modifies and packages proteins and other molecules into vesicles for transport
• Lysosomes


  Contain digestive enzymes to break down molecules and organelles
• Mitochondria


  The 'powerhouses' of the cell, where cellular respiration occurs
• Peroxisomes

  Contain enzymes to break down toxic substances and produce hydrogen peroxide
• Plastids


  Found in plant cells, include chloroplasts for photosynthesis
• Vacuoles


  Membrane-bound compartments that store and transport substances
• Ribosomes


  Sites of protein synthesis, found in the cytoplasm and attached to the rough ER
• Rough endoplasmic reticulum


  Has ribosomes on the outside
• Smooth endoplasmic reticulum


  Has folded membranes but no ribosomes on the outside
• Golgi apparatus


  Has folded membranes making cisternae, slightly more curved in shape than smooth ER, has vesicles budding off the edges
• Golgi apparatus function


  Proteins are processed and packaged, carbohydrates added to proteins to make glycoproteins, secretory enzymes made, lipids transported, modified and stored, molecules labelled with destination, finished products released in vesicles which fuse with cell membrane
• Lysosomes


  Vesicles containing digestive enzymes, can fuse with phagosomes to hydrolyze and destroy pathogens, involved in breaking down dead cells, fuse with cell membrane to release contents
• Mitochondria

  • Double membrane-bound organelle, inner membrane folds to create cristae, site of aerobic respiration and ATP production, contains own ribosomes and DNA
• Ribosomes


  Small, made of protein and RNA subunits, 80S in eukaryotes, 70S in prokaryotes and organelles like mitochondria, site of protein synthesis
• Chloroplasts


  Found in plant cells, double membrane, internal folded membranes called thylakoids stacked into grana, site of photosynthesis
• Cell walls


  Found in plants (cellulose) and fungi (chitin), provide structural strength