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

Explain management strategies for genetically modified crops, Explain Manag...

Explain Management strategies for genetically modified crops? Crops that have been genetically modified (GM) to be toxic to insect pests are now common in US agriculture. Make

What is deuterostome. explain in brief., What is Deuterostome. Explain in b...

What is Deuterostome. Explain in brief. Phyla, including the Chordata and Echinodermata which share common characteristics of blastopore-not forming the mouth, radial indetermi

Multipotent scs-pulp tissue revascularization, Multipotent SCs: are cells ...

Multipotent SCs: are cells differentiated & form a number of other tissues, while their sources are not fetal tissue; umblical cord blood & postnatal stem cells including dental p

Evaluate the moisture requirement, Evaluate the Moisture Requirement - The ...

Evaluate the Moisture Requirement - The Concept of Water Activity We already know that moisture is one of the important factors for the survival of living species. As suc

Aeromonas associated zoonotic disease, Aeromonas associated zoonotic diseas...

Aeromonas associated zoonotic disease Aeromonas causes gastrointestinal infections and extra intestinal infections such as cellulitis, wound infectiopn, peritonitis, endocardi

Explain the meaning of transfer of culture, Explain the Meaning of Transfer...

Explain the Meaning of Transfer of Culture Transfer of culture can be done from one liquid media to another liquid media or from liquid to solid media or vice versa. The steps

Abnormal violent contractions of skeletal muscles, Person Z swallowed a lar...

Person Z swallowed a large amount of substance X and, as a result, has convulsions (abnormal violent contractions of skeletal muscles).  Swallowing which of the following substance

What are gametes, What are gametes? Gametes are cells specialized in s...

What are gametes? Gametes are cells specialized in sexual reproduction. They have half of the maximum number of chromosomes of the species and unite with another gamete giving

What are the bacteria, Q. What are the bacteria? Bacteria are unicellul...

Q. What are the bacteria? Bacteria are unicellular and prokaryotic beings. Bacteria have simple organization they present an exterior cell wall, plasma membrane, circular DNA w

Implantation, IMPLAN TA TIO N - Attachement of blastocyst on the ...

IMPLAN TA TIO N - Attachement of blastocyst on the endometrium of the uterus is called implantation. Generally it occurs 7th day after fertilisation. (6-10 days). Blas

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