• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

Essay on microscopy. There are two types of electron microscope, transmission and scanning microscopes.

Extracts from this document...


Electron Microscopy There are two types f electron microscope, transmission and scanning microscopes. The transmission electron microscope produces sharp definition at low magnification, as it presents a 2D image whereas the scanning electron microscope does not have such high resolving power but gives a three-dimensional effect showing surface detail. An electron microscope is preferred over a light microscope since it has the ability to produce higher magnification, which increases the amount of visible detail, as well as higher resolution, since increasing the resolving power of a microscope depends on the wavelength of the electromagnetic radiation used. Therefore an electron beam is used resulting in a smaller wavelength is needed. ...read more.


In other procedures the specimen does not have to be cut into thin sections but the surface is coated with a thin film of gold, The tissue is soaked in alcohol to dehydrate it Tissue is embedded in a resin which becomes hard. The embedded tissue is cut using a microtome or into very thin sections using a knife made of glass. Very small specimens such as viruses and large molecules do not have to be sectioned. Prior to sectioning and cutting tissue is preserved using substances which prevent enzyme action The general outline for freeze facture technique consists of cells frozen quickly in liquid nitrogen which stops cell components instantly. ...read more.


To do so it uses electromagnets to focus the image onto a fluorescent screen, the specimen can then be viewed via low and high magnification. The specimen can not be a living cell. Electron beams can not pass through glass and likewise can not be used to look at living cells, since the atoms in organic molecules have a low atomic number and so do not scatter electrons. In a scanning electron microscopes an image is emitted or reflected from the surface of a complete specimen. The similarity between a scanning electron microscope and a transmission electron microscope are specimens must be stained in order to improve contrast. Important since a high-intensity electron beam can destroy parts of the specimen, producing light-coloured areas on the screen. ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our AS and A Level Molecules & Cells section.

Found what you're looking for?

  • Start learning 29% faster today
  • 150,000+ documents available
  • Just £6.99 a month

Not the one? Search for your essay title...
  • Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

See related essaysSee related essays

Related AS and A Level Molecules & Cells essays

  1. Cells Essay.

    Ribosomes are large (80s) No cytoskeleton Always has a cytoskeleton Advantages of using optical and electron microscopes in studying the structure of cells The electron microscope has a greater resolution than a light microscope. It uses an electron beam instead of light, and electromagnets instead of glass lenses.

  2. Compare the organization of two eukaryotic cells using the details revealed by light and ...

    The cell membrane is partially permeable to control entry and exit of substances it may also be infolded in places to form a large surface area. Plant cells also contain plastids e.g. chloroplasts and leucoplasts these are present in large numbers where as they are not present in animal cells.

  • Over 160,000 pieces
    of student written work
  • Annotated by
    experienced teachers
  • Ideas and feedback to
    improve your own work