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

Electron Microscopy and the study of the Cell.

Extracts from this document...

Introduction

Electron Microscopy.

Electron Microscopes have revolutionised today’s understanding of the cell.  In 1838 Scheleiden, a botanist theorised that the basic unit of a plant was a cell, the following year the scientist Schwann came up with a similar hypothesis this time related to animal cells, their combined ideas gave us the cell theory, the idea that all living things were made from similar building blocks, cells.  It took 100 years before this idea was confirmed with the invention of the electron microscope.  Prior to this light microscopes, which enable us to see large cells, were used; but their resolving power was not high enough to confirm that all living things were made from cells as the physics of a light microscope only enables it to magnify something by about 2000x, a resolution of about 0.2 micrometers.  In this essay I will be discussing the uses of electron microscopes, the way in which they are used and also comparing the electron and light microscopes.

...read more.

Middle

There are 2 types of electron microscope, the scanning electron microscope and transmission electron microscope.  Transmission electron microscope create a 2D image of the cross-section of a sample, this microscope type has the highest resolving power.  Scanning electron microscopes give a 3D effect and show surface detail.

When looking at a specimen under an electron microscope the specimen must thin enough for electrons to pass through, about as thin as the film around a soap bubble.  There are two ways of preparing a sample for electron microscopy, negative staining and freezing.  Negative staining involves using an element such as uranium or gold to stain a sample.  An electron micrograph is an electron density map.  Elements such as Carbon, Hydrogen and Oxygen, which make up the largest portion of most cells, are not electron dense (do not contain many electrons), so they create a faint electron micrograph.  Staining the sample with elements which are electron dense means that there is a large contrast and the sample can be seen more clearly.

...read more.

Conclusion

I think these differences mean there is a demand for both microscopes, although the electron microscope has revolutionised cell biology there will always be a need for the light microscope.

...read more.

This student written piece of work is one of many that can be found in our AS and A Level Microscopes & Lenses 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 Microscopes & Lenses essays

  1. Peer reviewed

    The history, development and use of the light and electron microscope

    3 star(s)

    The higher the resolution the clearer the image seen. The image will appear to be better if you increase in resolution with no change in magnification.

  2. My experiments focus is to obtain an accurate measurement for a specific lenss power.

    This results in an average of 6.595+/- 0.005 D. This uncertainty is much smaller than the previous experiments; first experiment (0.02D), second (0.125D) and third (0.055). In comparison to the claimed power of 6.67 Dioptres, the result is 0.105 Dioptres out; hence there is an error of (0.105/6.67)x100= 1.57% provided the claimed power is correct.

  1. Optical and Electron Microscopy

    Figure 1: Note that there are actually more lenses in the compound microscope through which light passes. These correct imperfections such as aberrations - the inability of a lens to be light of different colours to focus at the same point (chromatic aberration), or the failure of a lens to

  2. Scanning Tunnelling Microscopy.

    This provides a very fine resolution of the surface. Quantum Mechanical Tunnelling The infinite potential walled particle in a box theory does not allow any of the wave function to escape the box as it would have to have more than infinity energy to cross the barrier.

  1. Bradford Museum of Film and Photography

    This is all done by total internal reflection. In researching about fibre optics in the museum and from other sources including textbooks and the internet I have found out that they

  2. Electron Microscopy.

    If a vacuum is present then life cannot exist within it and so the microscope cannot look at living cells. Also the tissue needs to be preserved using substances that will prevent enzyme action. The tissue also needs to be soaked in alcohol to dehydrate it and make the organelles in cells more visible.

  1. Find the separation between two cones of the same type on the fovea of ...

    This will be controlled by having the light sources at a height of 1 metre and having the viewer use a metre ruler as a guide to the height of their eyes when resolving the light sources. * The size of the eye and the strength of eyesight must be constant throughout the experiment.

  2. How has the Invention of Contact Lenses affected people's Sight?

    There are two main designs: the power or seeing far is concentrated at the top and the one of seeing nearby at the bottom, or the different powers are blended on different parts of the lens. * Coloured contact lenses: they can be used to correct existent sight troubles, but

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