Transmission electron microscopy, Biology

Assignment Help:

Transmission Electron Microscopy

The source of illumination in a TEM is a tungsten filament that emits electrons. A vacuum is created to prevent the collision of electrons with anything else except the specimen. The electron beam is focused by different electromagnetic coils (lenses). First electrons are collected and focused in an electromagnetic 'condenser' lens and then they are collected again by an 'objective' lens. The electromagnetic objective lens produces a magnified image of the object which is received by 'ocular or projection' lens. The final image is formed either on a photographic plate or on a phosphorescent screen. The image results from differential scattering of electrons from molecular constituents of the cell.

If you compare the functioning of a TEM with a LM, you will observe that while there are many similarities between a LM and a TEM. there are also many differences. The image formation in a LM depends on the degree of light absorption whereas in a TEM it depends on electron scattering. The lenses of LMs are glass lenses and focusing is done by moving them nearer or farther away from the specimen. In TEMs all the lenses are electromagnetic coils and focusing is done by manipulating the amount of current flowing through the magnetic coils. The final image in a LM is seen by the eye whereas in a TEM it is formed on a phosphorescent screen.


Related Discussions:- Transmission electron microscopy

Plants and animals - biological weathering, Plants and animals The acti...

Plants and animals The activity of living organisms like lichens, fungi, bacteria, blue green algae, bryophytes is also responsible for weathering.  It is referred to as biolog

How pathogenic bacteria cause diseases, What are some mechanisms by which p...

What are some mechanisms by which pathogenic bacteria cause diseases? Why is this knowledge important? Pathogenic bacteria have characteristics called as virulence factors that

Define oseltamivir, Oseltamivir (Tamiflu)   This oral neuraminidase i...

Oseltamivir (Tamiflu)   This oral neuraminidase inhibitor, started within 36 hours of symptom onset, can decrease the severity and duration of symptoms caused by either influ

Develop a hypothesis relating to the amount, Develop a hypothesis relating ...

Develop a hypothesis relating to the amount of dissolved oxygen measured in the water sample and the number of fish observed in the body of water.

Fertilisation, Explain how the uterus supports the development of a baby du...

Explain how the uterus supports the development of a baby during gestation

Determine the term mentalis, Mentalis The mental tubercles on either si...

Mentalis The mental tubercles on either side of mental protruberance(in midline) gives origin to the mentalis muscle. Above the mentalis origin, the incisivus muscle takes orig

Inhibition of microorganisms in food, Q. Inhibition of microorganisms in fo...

Q. Inhibition of microorganisms in food? Microorganisms use our food supply as a source of nutrients and energy. They increase their numbers by utilizing nutrients. This can re

A decrease in blood plasma levels of calcium, A decrease in blood plasma le...

A decrease in blood plasma levels of calcium will lead to A. an increase in the calcium ion excretion in the urine. B. an increase in the calcium ion absorption from the con

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd