first electron microscope

Wave nature of material objects In 1924, de Broglie's suggested that all material objects including an electron have a dual character; they behave as particles as well as waves. The wavelength associated with a particle of mass 'm', moving with velocity 'v' is given by de Broglie's rel..

>thylakoids. A thylakoid of one granum is connected to other granum with the help of a membrane. It is called stroma lamellae. The lower epidermal layer of the leaves have specialised cells which guard the openings called the stomata. It is through the stomata that the carbon dioxide enters and the..

Dual Nature of Matter and Radiation - Light has been regarded as waves to explain the phenomena of reflection, refraction, diffraction etc. However in 1905, Albert Einstein suggested that light has a dual character, which means, it can behave as a particle as well as a wave. It was observed that so..

In 1831, Robert Brown discovered the nucleus in the cell J.E.Purkinje, in 1840, used the term protoplasm to describe the juicy, slimy gelatinous contents of the cell In 1885, Rudolf Virchow expressed that all cells arise from pre-existing cells In 1932, two German Scientists, Ruska and..

matrix or stroma. In the cross-section of the grana, lamellae form sac like structures called thylakoids. A thylakoid of one granum is connected to other granum with the help of a membrane. It is called stroma lamellae. Section of Chloroplast as seen under electron microsco..

>Similar to light, matter also manifests itself in the form of particles as well as waves. Compton effect, and Davison and Germer's experiment stand as evidence for dual nature of matter. If an electron acts as a wave, its wavelength is calculated to be Davison and Germer showed the ..

. In 1932, two German Scientists, Ruska and Knoll, invented the electron microscope. Man is estimated to have about 100 trillion (10 1 4 ) cells in numbe..

Every cell, whether it is prokaryotic or eukaryotic, is enclosed in a thin covering called cell membrane . It is also called as plasma membrane or plasma lemma . The cell membrane can only be seen through the electron microscope since its thickness is well below the resolving po..

Every organism consists of parts that can be arranged in increasing levels of complexity. Each higher level is more complex than the one below it. The smallest structural unit of matter, both non-living and living are protons, neutrons and electrons. These particles combine in a specific ..

Unit Membrane Concept - The molecular structure of cell membrane is still not clearly known. Several models have been proposed from time to time to explain its structure based on its physico-chemical properties. In the year 1935 Danielli and Dawson proposed that the cell membrane is made up of a li..