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

Uses of grafting, Uses of Grafting Grafting helps to preserve and pe...

Uses of Grafting Grafting helps to preserve and perpetuate varieties that cannot reproduce by vegetative method. Grafting changes less useful varieties to more desirable

Unilateral incompatibility, Unilateral Incompatibility This relates to...

Unilateral Incompatibility This relates to incompatibility that operates in one direction. The most common way to ascertain unilateral incompatibility is to perform crosses be

What is the acrosome of the sperm cell, What is the acrosome of the sperm c...

What is the acrosome of the sperm cell? How is it formed? The acrosome is a structure that has a great number of digestive enzymes, it is located in the anterior end of the spe

Define the poverty and hunger as a causes of malnutrition, Define the Pover...

Define the Poverty and hunger - mutually causes, devastating effects? Measures of food deprivation, nutrition and poverty are strongly correlated. Countries with a high prevale

What is the kind of nitrogen waste that mammals eliminate, Q What is the ki...

Q What is the kind of nitrogen waste that mammals eliminate? Like chondrichtian fishes and adult amphibians, mammals are ureotelic that is they excrete urea. Q. How do plac

Which organ releases the female gamete under formation, Q. What is the orga...

Q. What is the organ that releases the female gamete under formation? How is this release triggered? What is the organ that collects the released gametes? The organ that libera

How many bones in the human face, Explain how many bones in the human face?...

Explain how many bones in the human face? Ans) 14 bones are present in human face and these bones are known as sepio

Explain interaction of pyridoxine with carbohydrates, Explain Interaction o...

Explain Interaction of pyridoxine with Carbohydrates? Pyridoxine is involved in glyconeogenesis through its action in transaminase reactions. Low levels of pyridoxine impair gl

What is the function of the feet in molluscs, Q. What is the function of th...

Q. What is the function of the feet in molluscs? How is the mollusc foot related to the name given to the classes of the phylum? The mollusc foot has the function of support, l

What is the first polar body, What is the first polar body? How different i...

What is the first polar body? How different is it from the oocyte II? In oogenesis the oogonium differentiates into oocyte I (2n) and this cell enters meiosis. After finishing

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