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

Conduction of impulse, CONDUCTIO N OF IMPULSE - IN NON-MYELINATED AXO...

CONDUCTIO N OF IMPULSE - IN NON-MYELINATED AXONS - The impulse moves along the axon as local effect by altering the permeability of neighbouring Na +  channels and af

What are the major cellular features of fungi, Q. What are the major cellul...

Q. What are the major cellular features of fungi? There are pluricellular and unicellular fungi. All fungi are heterotrophs and eukaryotes. Fungi have cells with cell wall m

How can we prevent the misuse of discoveries about the brain, How can we pr...

How can we prevent the misuse of discoveries about the brain, such as those that suggest how learning and cognition might be enhanced? A. Ethical use and application of neurosc

Flower, flowers formation without any leaves?

flowers formation without any leaves?

Define the term - clinical neuropsychology, Clinical Neuropsychology Cl...

Clinical Neuropsychology Clinical neuropsychology is the application of neuropsychological knowledge to the assessment, management and rehabilitation of people who have suffere

What are toxic effects of lectins or haemagglutinins, What are toxic effect...

What are toxic effects of lectins or haemagglutinins? Well, these can cause growth inhibition in animals and diarrhoea, nausea, bloating and vomiting in case of human beings. W

Explain weight gain during pregnancy and foetal outcome, Explain Weight Gai...

Explain Weight Gain during Pregnancy and Foetal Outcome? Weight gain and birth weight are indisputably related to each other. Several studies have shown a higher occurrence of

What process causes oxygen to pass from the alveoli, What process causes ox...

What process causes oxygen to pass from the alveoli into the lung capillaries? Diffusion is the process by which oxygen passes from the alveoli to the lung capillaries.

The identity and amounts of elements in the molecule, If the chemical formu...

If the chemical formula of a substance is C17 H 31 COOH, what can you tell about the identity and amounts of elements in the molecule? Can someone please explain me this?

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