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

Build a genomic dna library, Construct a genomic DNA library with the help...

Construct a genomic DNA library with the help of some methylaee and finall do viral packaging.

Indirect uses of biodiversity, The cost of replacing these indirect uses of...

The cost of replacing these indirect uses of biodiversity, even if it were technically possible, would be so high as to render it impossible to duplicate. We also do not know how

Features of the gastrulation, Features of the Gastrulation The signifi...

Features of the Gastrulation The significant features of the gastrulation are: a) Proteins of many new types that were not present in the egg or blastula begin to be synthe

Peroxisome and lysosome, e use itwhat is difference between peroxisme and l...

e use itwhat is difference between peroxisme and lysosome what is function of it and where w

What a diploid cell contains, A diploid cell contains: A.one half of a comp...

A diploid cell contains: A.one half of a complete set of chromosomes B.several complete sets of chromosomes C.the correct number of chromosomes D.two complete sets of chromosomes E

Locomotion, Locomotion All animals, simple or complex, are able of per...

Locomotion All animals, simple or complex, are able of performing necessary bodily functions. One of these functions is Locomotion. Motility is one of the characteristics and

Chloroplasts , Chloroplasts Like mitochondria, chloroplasts are also di...

Chloroplasts Like mitochondria, chloroplasts are also distinctive organelles of eucaryotic cell. But they are found only in plant cells. Chloroplasts contain membranes forming

Define the miscellaneous applications of sugar, Define the Miscellaneous Ap...

Define the Miscellaneous Applications of Sugar? Sugars are used in 1. Custards, 2. puddings, 3. pie fillings and meringues Depending on the sugar to perform vital c

Proteins of animal origin - shell fish, Proteins of Animal Origin - Shell F...

Proteins of Animal Origin - Shell Fish Shell Fish: Information on shellfish is fragmentary and incomplete. In shell fish, the shell comprises of a large portion of live weight

Regulation of senescence, Regulation of Senescence Senescence is a par...

Regulation of Senescence Senescence is a part of a developmental sequence of events and has to be a controlled process. You must have seen that if you cut twigs having leaves

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