microscopy

• Microscopy allows use to view cells and even their sub-cellular structures under microscopes.
• Light microscopes:

  • use light to form images.
  • can only view living samples.
  • relatively cheap
  • low magnification+resolution
  • can view animal, plant, bacterial however not able to distinguish sub-cellular structures apart.
  • Max mag of only x1500 and res of up to 0.2 μm
• Electron microscopes:

  • Uses beam of electrons form images.
  • Can do living and non-living samples.
  • High magnification+resolution.
  • Able to see sub-cellular structures in high amounts of detail, e.g scientists able study functions of ribosomes, mitochondria, chloroplasts in heavy detail
• Magnification tells us how much bigger object is compared to its actual size.
• Resolution, is the ability to distinguish two or more objects that are close together.
• magnification=image size/actual size
• Required Practical:

  1. Place thin sample of onion epidermis onto slide.
  2. Add few drops of stain/dye
  3. Place coverslip (at an angle to avoid bubbles) on top of tissue and place onto microscope stage.
  4. Use objective lens with lowest mag and focus on the sample.
  5. Increase magnification and refocus to view different features of cell.
• Microscope key labels