Recombinant DNA technology is one of the advanced strategies of the Biological science

The term Biotechnology was coined by the scientists “Carl neuberg” in 1919.

The origin of biotechnology can be traced back to prehistoric times, when microorganisms were already used for processes like “Fermentation”.

First Discovery: In 1920, “Clostridium acetobutylicum” was used by “Chaim Weizmann” for converting starch into butanol and Acetone. The latter was an essential component of explosives during World War-I.

Second Discovery: During Second World War (1940s), the production of Penicillin (as an antibiotic discovered by “Alexander Flemming” in 1929) on a large scale from cultures of “Pencillium notatum”

Third Discovery: The third discovery of Biotechnology is its recent reincarnation in the form of “Recombinant DNA technology”, which led to the development of a variety of gene technologies and is thus considered to be the greatest scientific revolution of this century.

An early demonstration of the transfer of DNA from one cell type to another concerned drug resistance of certain strains of E.coli could be transformed to a phenotypic bacterium such as “Salmonella”. The explanation of this phenomenon led to the discovery of the plasmid, where by the gene conferring antibiotic resistance residues in a form of extra-chromosomal DNA. The resistance is due to an enzyme that causes the degradation of the antibiotic.

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All genetically relevant information contained in any nucleic acid molecule resides in its base sequence, so the prime role any mode of replication is to duplicate the base sequence of the parent molecule. The specificity of base pairing – Adenine with Thymine and Guanine with Cytosine – provide the mechanism used by all replication systems. Further more

1. Nucleotide monomers are added one by one to the end of a growing strand by an enzyme called a DNA polymerase.

2. The sequence of base in each new or daughter strand is complementary to the base sequence in the old or parent strand being copied – that is, if there is an adenine in the parent strand, a thymine will be added to the end of the growing daughter strand when the adenine is being copied.

In the following section we consider how the two strands of a daughter molecules are physically related to the two strands of the parent molecule.

Replication can be broadly defined as genome duplication, an essential process for the propagation of cellular genome and those of ‘Molecular parasites’ – Viruses, plasmids and transposable elements. The genome to be duplicated is the parental genome, and the copies are daughter genomes.

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Immunology is the study of the immune response. It has tremendous advances in the last 3 decades. In Latin “Immunitis” means “Freedom from Burdens” It is the slogan of second world war soldiers. The Father of Immunology and microbiology is Louis Pasteur” (1822 to 1895).

Animal encounter many potentially dangerous microbes in air, water and food. They have evolved co-operative types of defense mechanism against the disease causing microbes. These mechanisms maintain homeostasis to keep the animals alive. Infact human body is a closed container. If a parasite is to establish it must first penetrate the layer of this container. Intact skin and its extension into the gastrointestinal, respiratory and urinary tracts represent the major form of infection and diseases.

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