Sulphur cycle

Sulphur cycle

Sulphur cycle Sulphur is found in living organisms in the form of compounds such as amino acids, coenzymes and vitamins. It can be utilised by different types of organisms in several forms. In its elemental form, sulphur is unavailable to most organisms. However, certain bacteria such as Acidithiobacillus are able to oxidise it to sulphate, a …

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Nitrogen Cycle

Nitrogen Cycle All organisms need nitrogen to synthesize protein, nucleic acids, and other nitrogen containing compounds. Molecular nitrogen (N2) makes up almost 80% of the Earth’s atmosphere. For plants to assimilate and use nitrogen, it must be fixed, that is, taken up and combined into organic compounds. The activities of specific microorganisms are important to …

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Agglutination

Agglutination Agglutination is an antigen–antibody reaction in which an antigen combines with its antibody in the presence of electrolytes at a specified temperature and pH resulting in formation of visible clumping of particles. Agglutination occurs when antigens and antibodies react in equivalent proportions. Agglutination reactions have a wide variety of applications in the detection of both …

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Immunofluorescence

Immunofluorescence

Immunofluorescence The property of certain dyes absorbing light rays at one particular wavelength (ultraviolet light) and emitting them at a different wavelength (visible light) is known as fluorescence. Fluorescent dyes, such as fluorescein isothiocyanate and lissamine rhodamine, can be tagged with antibody molecules. They emit blue-green and orange-red fluorescence, under ultraviolet (UV) rays in the …

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Precipitation

Precipitation

Precipitation Precipitation shows the following features: It is a type of antigen–antibody reaction, in which the antigen occurs in a soluble form. It is a test in which antibody interacts with the soluble antigen in the presence of electrolyte at a specified pH and temperature to produce a precipitate. A lattice is formed between the …

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Antigen Antibody Reactions

Antigen Antibody Reactions

Antigen Antibody Reactions Introduction The interactions between antigens and antibodies are known as antigen antibody reactions. The reactions are highly specific, and an antigen reacts only with antibodies. These reactions are essentially specific, they have been used in many diagnostic tests for the detection of either the antigen or the antibody. The antigen and antibody …

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Sterilization

Sterilization

Sterilization Sterilization Sterilization is defined as a process by which an article, surface, or medium is freed of all living microorganisms. Any material that has been subjected to this process is said to be sterile. Methods of sterilization can be broadly classified as: Physical methods of sterilization. Chemical methods of sterilization. Physical methods of sterilization …

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Bacterial Growth Curve

Bacterial Growth Curve

Bacterial Growth Curve When a broth culture is inoculated with a small bacterial inoculum, the population size of the bacteria increases. The bacterial growth curve shows the following four distinct phases. Lag phase, Log phase, Stationary phase, Decline phase. Lag phase: After a liquid culture broth is inoculated, the multiplication of bacteria does not start immediately. It takes …

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