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

Calculate the volume of a 25% urethane, Assume that the blood volume of a r...

Assume that the blood volume of a rabbit is 0.5 liters. If the effective dose of the anesthetic urethane is 10 µgrams/ml of blood, calculate the volume of a 25% urethane solution t

Natural disasters, EARTHQUAKES          An earthquake with its terrible...

EARTHQUAKES          An earthquake with its terrible aftereffects is one of the most frightening and destructive phenomena of nature. It can be defined as a sudden movement of

Mechanism of carcinogenesis, Mechanism of Carcinogenesis In the preced...

Mechanism of Carcinogenesis In the preceding sub-section you learnt that carcinogenesis is a multistep process. Even though cancer may be caused by many agents chemical, p

What is fenugreek seeds, Q. What is Fenugreek seeds? Fenugreek seeds: '...

Q. What is Fenugreek seeds? Fenugreek seeds: 'Commonly known as methi seeds in Hindi. They are commonly used in Indian cuisine in chutney and even in pickles and several dishes

Explain about the oesoplzageal carcinoma, Explain about the Oesoplzageal Ca...

Explain about the Oesoplzageal Carcinoma? Management of patients with oesophageal carcinoma includes surgery, radiation and combination chemotherapy. Radiation to the lower nec

Periods of cultural evouition and modern man, PERIOD S OF CULTURAL EVOUITI...

PERIOD S OF CULTURAL EVOUITION AND MODERN MAN - Paleolithic period: Stone age. Age of tools of stones and bones, cave paintings. Mesolithi c period: Age of domesticati

Determine the seeds in the plant kingdom, What is the evolutionary importan...

What is the evolutionary importance of the emergence of seeds in the plant kingdom? The evolutionary significance of the seed is related to the plant capability of distant colo

Explain about the biuret method, Explain about the Biuret Method? The B...

Explain about the Biuret Method? The Biuret reaction was one of first colorimetric assays developed for protein estimation. It is most often used in applications requiring a fa

Differences between prokaryotes and eukaryotes, Differences between Prokary...

Differences between Prokaryotes and Eukaryotes It is obvious that there are a number of differences between them. Prokaryotes, like bacterial cells are generally much smaller,

Conditions essential for the germination of seeds, To study the conditions ...

To study the conditions essential for the germination of seeds:- In the diagram below a having seeds on cotton wool with air, warmth, but no water; b has water, warmth, but no

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