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

Methods useful in self-incompatibility, Methods Useful in Self-Incompatibil...

Methods Useful in Self-Incompatibility More specific methods useful in overcoming self-incompatibility are mentioned below 1. Bud Pollination : In Petunia axillaris early

What are mitochondria, Mitochondria are the organelles in which the most si...

Mitochondria are the organelles in which the most significant part of the cellular respiration happens: the ATP production.

Basics of echocardiography, Echocardiography is one of the -most frequent...

Echocardiography is one of the -most frequently used imaging modalities for diagnosing cardiovascular diseases. It i's versatile and is applicable in the entire spectrum of

Deficiency diseases-evaluation of production diseases, Evaluation of produc...

Evaluation of production diseases Generally, production diseases are acute states and respond dramatically to administration of a deficient nutrient or metabolite. The nutriti

Ecosystem, what is the main excretory organ of a lizard

what is the main excretory organ of a lizard

Effects of noise - noise pollution, Effects of Noise - Noise Pollution ...

Effects of Noise - Noise Pollution Noise can affect in the following three ways: Interferes with communication, Diminishes hearing and Affects health and even

Cell, compare and contrast plant cell and animal cell with labeling diagram...

compare and contrast plant cell and animal cell with labeling diagrams

Organization in non-reduced embryo sacs , Organization in non-reduced embry...

Organization in non-reduced embryo sacs The fate of a nucleus in the embryo sac depends upon its position. Many irregularities in the disposition of nuclei in the early polar

Active instruments-coronal disassembly devices, Active instruments - Do...

Active instruments - Do groove occlusally or buccally until reach tooth structure - Apply this instrument then screw to break the bond between tooth structure and crown GC

Limb regeneration in anuran amphibians, Limb Regeneration in Anuran Amphibi...

Limb Regeneration in Anuran Amphibians We are already aware that the limb of adult frogs does not regenerate later than amputation. Though, some regeneration has been found to

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