Transmission electron microscopy, Biology

Assignment Help:

Transmission electron microscopy:

Around 1931-32 two German scientists. Knoll and Ruska. Invented transmission electron microscopy, and built the first transmission electron microscope (TEM) in 1938 .Hillier 1940 built a high resolution TEM. A strong beam of electrons, issued from tungsten filaments, passed through vacuum  and focussed by electromagnets, producing a radiation wavelength   of about 0.0005nm is used to  illuminate objects in this electrons  strike against a fluorescent screen, or directly fall onto a photographic film, producing an electron micrograph. A practical resolution of about 5 a and magnification of one to several hundred thousand have been achieved by this  microscopy, combined with modern cytological techniques, this microscopy has enabled scientists to know of many  finer details of cell structure down to the macromolecular level. This knowledge of ultra structure or sub microscopic structure of the cell has resulted into the establishment of Molexular Biology.

Knoll (1935) demonstrated the feasibility of scanning electron microscopy achieving a resolution of about 30 a for three dimensional study of surface topography of objects in considerable details. Von Adrienne (1938) built first scanning electron microscope (SEM) .It is smaller and simpler than TEM. Electrons used SEM does not pass through the object, but are simply scattered from the surface of the object.              


Related Discussions:- Transmission electron microscopy

Synthetic petrol, Petrol or gasoline can be synthesized by following three ...

Petrol or gasoline can be synthesized by following three methods: 1.      Polymerisation 2.      Fischer - tropsch method 3.      Bergius process polymerisation In

Explain the mechanism of temperature regulation, Any significant variation ...

Any significant variation in the internal temperature could have damaging effects on the body's enzymes. Homeotherms or warm-blooded animals including human can however generate co

Muscles, what process provides the energy for muscle contraction?

what process provides the energy for muscle contraction?

Operative requirements for stage i surgery, Operative requirements for stag...

Operative requirements for stage i surgery Although Implant placement under general anesthesia must be done in an operating theatre with complete resources, most implant surger

Zoology, The structure and formation of schizocoelous

The structure and formation of schizocoelous

Altitudinal variations, Altitudinal Variations We know that temperature...

Altitudinal Variations We know that temperature decreases with increasing altitude. This is mainly due to convection currents in the troposphere - the lowermost (and most dense

Define the term archenteron, Define the term Archenteron ? The name give...

Define the term Archenteron ? The name given to the primitive gut, the first tube that runs through the developing embryo and is open to the external environment. Formed during

Name two foods which are a good source of this vitamin, a) Which vitamin he...

a) Which vitamin helps to maintain resistance to infectious diseases? b) Name two foods which are a good source of this vitamin.   a) Vitamin A (retinol) helps m

Explain isomer, Isomer : Existence of different  compounds having  same ...

Isomer : Existence of different  compounds having  same  molecular form but different structural forms.

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