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
Q. Chordate identity card. How are they characterized according to examples of representing beings, type of symmetry, basic morphology, germ layers and coelom, digestive system, ci

Preparation on the Previous Day of Operation Remove all the jewellery, nail polish, cut nails.  The patient's body is cleaned - shaving from chin to toe, inclu

Q. Associated Foods with escherichia coli? Associated Foods: E. coli is the etiologic agent of food poisoning involves variety of foods such as cream pie, mashed potatoes, cr

Pneumonia Pneumonia is an inflammatory process in which there is consolidation in lung caused by exudates filing the alveolar spaces. Gas exchange cannot take place in the c

Q. Provision of Additional Tooth Support? Transitioning a patient from a complete denture to an implant supported fixed prosthesis have resulted in a dramatic improvement in th

Class of Crustacea - Branchiopoda These are small fresh water crustaceans. The trunk appendages are flattened and leaf like and are helpful for locomotion also respiration he

What are the structures that form the external ear? What is its function? The internal ear comprises the pinna, or auricle, and the auditory canal. Its function is to conduct t

Define Principle of Detection of Metanil Yellow? Non-permitted colours like lead chromate, metanil yellow, auramine, rhodamine B are used to brighten the foods especially spice

HOW TO WRITE A CONCLUSION ON A ASSIGNMENT OF EPITHELIAL TISSUES

Determine the types of symbols used in Soil Horizons  Three kinds of symbols are used in various combinations to designate horizons. These are capital letters, lower case lett