Transmission electron microscopy, Biology

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.              

Posted Date: 9/26/2012 7:10:05 AM | Location : United States







Related Discussions:- Transmission electron microscopy, Assignment Help, Ask Question on Transmission electron microscopy, Get Answer, Expert's Help, Transmission electron microscopy Discussions

Write discussion on Transmission electron microscopy
Your posts are moderated
Related Questions
Explain the biomechanics of cantilevers The biomechanics of cantilevers need to be understood. It has been found that when a three unit prosthesis is supported by two implants

Define Fluids required for underweight - nutritional care? Take fluids only after a meal instead of with or before meals so that food intake is not reduced. High calorie nouris


What is the difference between ectoparasite and endoparasite? Ectoparasites are parasites that explore the external surface of the host (as, for example, mites that parasite th

A fish of genotype a/a; B/b is crossed to a fish whose genotype is A/a; B/b. What proportion of the progeny will be heterozygous for at least one of the genes? (Assume independent

G L YCOGEN Polymer of a-D-glucose. It has 5000-30000 units of a-D-glucose. Glycogen is glucosan homopolysaccharide which is the major reserve food of animals, fungi and

Which of the following statements about hemoglobin and myoglobin structure are true? Select the five true statements. 1. By itself, heme is not a good oxygen carrier. It must be

What is difference between self pollination and cross pollination? Which of the two modes of pollination contributes more to the plant diversity? Self pollination take places w

Q. Dietary Fats required for dyslipidemia? Dietary Fats: There is a consistent support for the hypothesis that both the quantity and quality of fat are directly associated with

How implants increases the magnitude significantly The patient should be medically fit to undergo the surgery. Placement of one or two implants is equivalent to relatively mino