SDS-PAGE is an electrophoresis method that allows protein separation by mass. It is also known as sodium dodecyl sulphate polyacrylamide gel electrophoresis. In SDS-PAGE,  proteins are separated solely based on polypeptide chain length eliminating the influence of the structure and charge. This course covers SDS-PAGE, principle involved, process and applications of SDS-PAGE. Principle Involved Different … Read More

Restriction Enzymes

Restriction enzymes are bacterial enzymes that have the ability to cut double-stranded DNA at specific sites. These are also known as restriction endonucleases. They occur naturally in bacteria as a weapon to fight against the invading viruses. Restrictions sites in the viral genome are cleaved by the restriction enzymes. These are present in bacterium, fragmenting … Read More


A centrifuge is a device that uses centrifugal force to separate two or more substances of different density or mass (Figure 1). Basis of Separation Materials with heavier masses move faster and farther away from the central point than those with lighter masses. Principle Involved A centrifuge consists of a fixed base and a center … Read More

Paper Chromatography

Paper chromatography is an analytical technique used for separation of mixtures into their components for identification (Figure 1), purification, and quantification. It is a useful technique as it is quick, has high resolution and ease of detection when separating small samples. The mobile phase is usually an alcohol solvent mixture, while the stationary phase is … Read More

Applications of Radioactive Isotopes

Applications of radioactive isotopes are varied in several areas of science. It ranges from the field of agriculture to the diagnosis of diseases. Agricultural Applications Radioisotopes are being widely used in plant nutrition studies and several researches are being conducted in many countries for using radiation sources to preserve certain types of agricultural produce, such … Read More


Autoradiography involves localization, recording of a radiolabel within a solid specimen, and production of image in a photographic emulsion. These photographic emulsions consist of silver halide crystals suspended in a clear phase composed mainly of gelatin. In 1867, first autoradiography was obtained accidentally, when a blackening was produced on emulsions of silver chloride and iodide by … Read More


Spectrophotometry is a quantitative measurement of the reflection or transmission properties of a material as a function of wavelength. This  depends upon how much light is absorbed by a chemical substance. Measurement is done by recording the intensity of light absorbed as a beam of light passes through sample solution. A spectrophotometer is an instrument … Read More

Molecular Tools in Genomics

Molecular biology is the field of biology (Figure 1) that studies the interactions between the various systems of a cell. This interactions include the interrelationship of DNA, RNA and protein synthesis and carry out the biological processes essential for the cell functions and maintenance. Restriction enzymes are also called ‘molecular scissors’ as they cleave DNA … Read More

Cloning Vectors

A cloning vector or cloning vehicle is a DNA molecule in which foreign DNA can be inserted or integrated. This molecule is further capable of replicating within host cell to produce multiple clones of recombinant DNA. The cloning vectors commonly in use today are derived from viruses and bacteria. One of the most common of … Read More

Chemical Separation Techniques

Chemical separation techniques play a key role in analyzing molecules or compounds used for biological, physical, and chemical research. They are a powerful tool set to investigate mechanisms of various biological processes. It is used to separate a mixture into its two or more distinct components, which are used further for the analysis of physical … Read More