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

Changes in the ions, Changes in the Ions The concentration o...

Changes in the Ions The concentration of potassium, phosphate and nitrate declined significantly in the bathing medium within four days. The concentration of so

Types of parthenogenesis, TYPES OF PARTHENOGENESIS - 1 .      NATURAL...

TYPES OF PARTHENOGENESIS - 1 .      NATURAL PARTHENOGENESIS - In many animals natural parthenogenesis is common process & is a method of reproduction. It is of two typ

Explain the voges proskauer (vp) test, Explain the Voges Proskauer (VP) Tes...

Explain the Voges Proskauer (VP) Test? As it has been discussed in previous exercise, second group of enteric bacteria produces acid during early incubation which rapidly conve

Ross operation-surgical techniques, Ross Operation :  In this technic...

Ross Operation :  In this technically demanding operation, the aortic valve is replaced by patient's own pulmonary valve (autograft) and a pulmonary or aortic allograft (homo

Why biologists use comparative method, Normal 0 false false ...

Normal 0 false false false EN-IN X-NONE X-NONE MicrosoftInternetExplorer4

Functions of lysosomes, FUNCTIONS (1 )      Intracellular digestion -...

FUNCTIONS (1 )      Intracellular digestion - Individual cells may obtain food through phagocytosis. The same is digested with the help of lysosomes. It is of two types:-

Structure and content of halsted reitan battery, Structure and Content of ...

Structure and Content of Halsted Reitan battery Although there are several versions of the Halsted Reitan battery, the differences tend to be minor, and there appears to be a

Tissue culture, Note on production of haploid by tissue culture.

Note on production of haploid by tissue culture.

Explain the penicillium - fungi, Explain the Penicillium - Fungi? Class...

Explain the Penicillium - Fungi? Classification Kingdom - Mycetae Division - Amastigomycota Class - Ascomycetes Subclass - Plectomycetidae Order - Eurotiales

Define some precautions for measurement of ph, Define some Precautions for ...

Define some Precautions for Measurement of pH? 1. Never touch the membrane of the glass electrode with anything else except soft tissue paper since it is fragile and is easily

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