Microscopy

• Microscopy is the most important technique used in biology as it enables us to see and examine organisms and structures which cannot be seen with the naked eye.
• Magnification is an indicator of how much bigger the microscope image is than the actual object whereas resolution is the smallest interval measurable by a microscope.
• Magnification can be calculated by dividing the size of the image by the size of the real object.
• Sample preparation:

  • Fixation - use chemicals to preserve the live specimen keeping it in its natural state.
  • Dehydration use ethanol to remove water from the specimen
  • Staining use stains to colour the specimen. different types of tissue will pick up different stains which helps create a contrast and allows you to differentiate between different organelles.
  • Mounting mount onto a microscope slide making sure there is a coverslip placed on top.
• there are 2 types of microscopes:

  1. Light Microscopes - these are good for observing samples in a lab as they are cheap and portable. They have a lower magnification and resolution than electron microscopes, however.
  2. Electron Microscopes - these are good for examining organelles in high detail. They have a high magnification and resolution, but samples must be placed in a vacuum and prepared first. This technique can be very expensive.
• Rules for scientific drawings:

  • Ensure you are using a sharp pencil
  • Draw continuous lines
  • Use plain white paper
  • Make sure the drawing takes up as much of the paper as possible
  • No shading
  • Label lines shouldn’t cross over each other
  • Label lines should be straight and drawn with a ruler
  • Label lines should not have arrow heads
  • Include a title for the drawing
  • State the magnification