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

Method of purchasing a service, Normal 0 false false false ...

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

Decay and nutrient cycling, Decay and Nutrient Cycling Soil organisms a...

Decay and Nutrient Cycling Soil organisms are the chief agents of decay of organic matter. Decomposition and mineralisation of organic matter results in release of inorganic nu

Advantages and disadvantages of solar energy, Advantage of solar energy: ...

Advantage of solar energy: 1.         It is renewable: it produce comes from sun, so it is plentiful and will always be there   as long we need it . 2.         Solar

Explain methodology required for osazone test, Explain Methodology Required...

Explain Methodology Required for Osazone Test? Take about 250-300 mg of phenylhydrazine mixture in the 3 clean labelled 15 ml dry test tubes. Add 5 ml of the glucose, fructose

Can you explain para-sternal view, Q. Can you explain Para-sternal View? ...

Q. Can you explain Para-sternal View? Various congenital anamolies can be detected in this view are perimembranous VSD (transducer anbled towards right hip), doubly commit

What body systems respond to resist the changes, Jennifer has the "stomach ...

Jennifer has the "stomach flu" that is going around campus and has been vomiting profusely for the past 24 hours. Not only has she been unable to keep down fluids or food but she h

Exchange in alveoli, Exchange in Alveoli The blood that enters the lun...

Exchange in Alveoli The blood that enters the lungs from the heart has been routed through body tissue where mitochondria1 respiration has depleted its oxygen content. It thus

Describe the process of coronary atherosclerosis, Q. Describe the process o...

Q. Describe the process of coronary atherosclerosis? Atherosclerosis is an intimal disease of arteries ranging in size from the aorta to the epicardial coronary artery i.e. cha

Explain monosaccharides, Monosaccharides :- Sugars consisting of  a  sin...

Monosaccharides :- Sugars consisting of  a  single  polyhydroxy  aldehyde or ketone unit.

Eukaryotic chromosomes, The vast amount  of genomic  DNA in a eukaryotic  c...

The vast amount  of genomic  DNA in a eukaryotic  cell is strongly  packaged  in chromosomes  having  within  a specialized  organelle and  the nucleus.  This very vast amount of e

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