PRINCIPLES OF BIOTECHNOLOGY | MANISH MEVADA | Biology

 PRINCIPLES OF BIOTECHNOLOGY

• Two Main Techniques of Modern Biotechnology.
• The two main techniques that gave birth to modern biotechnology are as follows
• Genetic Engineering
• It includes techniques to alter the nature of genetic material ( DNA and RNA ) to introduce these into hosi organisms and thus change the phenotype of the host organism.
• Chemical Engineering
• It involves maintenance of sterile microbial contamination free condition in chemical engineering processes to have growth of only the desired micro organism / eukaryotic cell in large quantities for the manufacture of biotechnological products such as antibiotics, vaccines, enzymes, medicines, hormones, etc.

Conceptual Development of the Principles of Genetic Engineering

• Genetic engineering is a kind of biotechnology which deals with the manipulation of genetic material by man in vitro.
• Two Main Discoveries. Genetic engineering is based on two important discoveries in bacteria.
• Presence of plasmids in bacteria which can undergo replication alongwith and independent of chromosomal DNA.
• Restriction endonucleases (Arber , Nathan and Smith 1970 ; Nobel Prize in 1978) which can break DNA at specific sites.
• They are appropriately called molecular scissors or biological scissors.
• Role of Paul Berg
• In 1972 genetic engineering was started by Paul Berg.
• Berg ( 1972 ) was able to introduce a gene of SV - 40 virus into a bacterium with the help of lambda phage.
• Berg is often considered " father of genetic engineering "
• He was awarded Nobel Prize in 1980.
• The technique of genetic engineering includes :
• Formation of ' recombinant DNA ' (rDNA).
• Use of gene cloning
• Gene transfer.
• It permits to isolate and introduce only one or a set of desirable genes without introducing undesirable genes into the target organism.
• A piece of DNA which is introduced into the alien (foreigo) organism would not be able to multiply itself the organism but when it gets incorporated into the genetic material al the recipicns, it may multiply and be inheriteu alongwith the host DNA, because the alien piece of DNA has become part of chromosome which possesses the ability to replicate.
• There is a specific DNA sequence called the origin of replication in a chromosome that is responsible for initiating replication.
• Thus, an alien DNA linked with the origin of replication, can replicate and multiply itself in the host organism.
• It is also called the cloning, i.e. , forming multiple identical copies of any template DNA

Construction of the First Artificial Recombinant DNA Molecule

• The first recombinant DNA was constructed by Stanley Cohen and Herbert Boyer in 1972.
• They cut the piece of DNA from a plasmid carrying antibiotic resistance gene in the bacterium Salmonella typhimurium.
• Cutting of a piece of DNA from a plasmid was with the help of restriction enzymes (also called molecular scissors or chemical scalpels).
• The piece of foreign DNA cut from the plasmid was linked with the plasmid DNA acting as vector.
• Linking of the piece of foreign DNA with vector was done with the help of the enzyme DNA ligase which acts on cut DNA molecules and join their ends.
• This newly formed DNA having integrated fragment of antibiotic resistant gene is called recombinant DNA.
• The vectors is used to transfer, recombinant DNA to E.coli.
• This transfer of recombinant DNA is similar to the transfer of malarial parasite from diseased person into the healthy person through female Anopheles mosquito (acts as an insect vector).
• When this recombinant DNA is transferred into Escherichia coli, it could replicate in the new host cell in the presence of DNA polymerase enzyme and make multiple copies of recombinant DNA.
• The ability to multiply copies of antibiotic resistance gene in E. coli was termed as cloning of antibiotic resistance gene in E. coli.

• Three basic steps in creating genetically modified organism (GMO) or transgenic organism.
• GMO contains a foreign gene / segment of DNA.
• These three basic steps are as follows.
• Identification of DNA with desirable genes
• Introduction of the identified DNA into the host.
• Maintenance of introduced DNA in the host and transfer of the DNA to its progeny.

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Manish Mevada

M.Sc, M.Phil, B.Ed

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