| Stain | Used for staining | more...
It is an another technique of separation. In which patricles of different charges and sizes are separated under the influence of electric field. e.g., nucleic acids, proteins, amino acids, nucleotides can be separated by this method. The technique was discovered by Russian physicist Alexender Reuss in 1807.
In immunoelectrophoresis antibodies coupled with radioisotopes, specific enzymes or fluorescent dyes are used in detection of particular proteins. The technique is highly sensitive. It can separate molecules in picogram and nanogram quantities and distinguish proteins which differ from each other in only one amino acid.
The concentration of various ions in different parts is now studies by using a glass microelectrode. It has silver wire dipped in KCl solution. This technique is used for studying the movement of ions through ions channels.
The ions channels are intrinsic membrane proteins. For studying this passive transport of ions through ion channels Neher and Sakman developed a Patch clamp technique for which they are awarded Nobel prize in 1991.
Microscopy (Gk. Micros = small ; skopein = to see) It is practice of using microscopes for the study of finer details of small objects including cells and tissues. Microscope are instruments consisting of lenses (made of glass / Lithium fluoride / electromagnetic lens) which magnify and resolve small objects not visible to unaided eye for the study of their details. The term microscope was coined by Faber in 1625.
Magnification : Is the power of enlargement, which is the ratio of
\[\text{Magnification}=\frac{\text{Size of the image with}\,\text{the instrument}}{\text{Size of the image with unaided eye}}\]
Magnification of a microscope is roughly equal to the multiple of magnifying power of objective lens and ocular lens (eye piece) e.g., if the magnification power of an ocular lens is \[10\,X\] and of the objective is \[40\,X,\] then the total magnifying power of a microscope is \[10\times 40=400\,X\] (the magnification power of a microscope is more...
Some of the biological molecules undergo changes after their synthesis. We can cite here the case of RNA. The transcription of hnRNA from DNA ultimately leads to the formation of m-RNA. These changes can be studied through pulse-labelling technique.
They are unstable isotopes which function like normal elements but emit positive or negative particles, e.g., \[^{3}H\](Tritium), \[^{14}C\](Carbon), \[^{32}P\](Phosphorus), \[^{35}S\](Sulphur), \[^{42}K\](Potassium), \[^{131}I\](Iodine). Radioactivity is recorded in different parts by Geiger counter or scintillation counter or autoradiography to know regions of use and transport. The tracers have been used for knowing pathway of mineral transport (Stout and Hoagland, 1939), organic solute transport (Vernon and Aronoff, 1952), carbon assimilation (Calvin, 1955).
Where radioactive elements are not available, heavy isotopes are used, e.g., \[^{15}N{{,}^{18}}O.\] Their fate is recorded by mass spectroscopy and density gradient centrifugation. Meselson and Stahl (1958) studied DNA replication and Ruben et al (1941) evolution of oxygen (photolysis of water) in photosynthesis by using heavy isotopes.
(1) Simple microscope : It is also known as magnifying glass and consists of a convergent lens.
Leeuwenhoek (1683) designed a primitive microscope and discovered cells with it. It was the first tool ever used to observe biological objects. Its magnification power was 14 – 42 times only, so it is considered as simple microscope.
(2) Compound microscope or Light microscope : The first compound microscope was assembled by Zacharias Janssen and J. Janssen, the Dutch spectacles makes in 1590. The compound microscope was prepared by Kepler and Galileo in 1611. However, it was not used for laboratory study. It is simplest, widely used microscope having three lens i.e., condensor, which collects the light rays and precisely focuses them on the objects; objective lens, which magnifies the image by three objective lenses, i.e., low power (10x), high power (45x) and oil immersion lenses.
In a compound microscope an object can more...
1 micron \[(\mu )={{10}^{-6}}\] or one millionth
1 micrometer \[(\mu m)={{10}^{-6}}m,\,\,{{10}^{-4}}cm,\,\,{{10}^{-3}}mm=1000nm\]
1 Nanometer\[(nm)={{10}^{-9}}m,\,\,{{10}^{-7}}cm,\,\,{{10}^{-6}}mm,\,\,{{10}^{-3}}\mu m=10\overset{{}^\circ }{\mathop{A}}\,\]
1 Angstrom \[(\overset{{}^\circ }{\mathop{A}}\,)={{10}^{-10}}m,{{10}^{-8}}cm,\,{{10}^{-7}}mm,\,\,{{10}^{-4}}\mu m.\]
1 Picometer \[(pm)={{10}^{-12}}m,\,{{10}^{-3}}nm\]
1 Femtometer \[(fm)={{10}^{-15}}m,\,{{10}^{-6}}nm\]
1 Attometer \[={{10}^{-18}}m,\,\,{{10}^{-9}}nm\]
Common unit of measurement in Microscopy and cytology is nanometer while unit of measurement of cell is micron.
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