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Principles of Biotechnology and Tools of Recombination DNA Technology:
1. Biotechnology can be defined as the use of microorganisms, plants or animal cells or
their components to produce products and processes useful to humans. According to the
European Federation of Biotechnology (EFB), biotechnology is the integration of natural
science and organisms, cells, parts thereof and molecular analogues for products and
services. The term ‘Biotechnology’ was coined by Karl Ereky in 1919.
2. Principles of biotechnology are based on the concept of the following techniques:
(i) Genetic engineering is the technique to alter the chemistry of genetic material
(DNA/RNA), to introduce these into another organisms and thus, change the phenotype of
the host organism.
(ii) Adequate maintenance of sterile conditions to support growth of only the desired
microbes/eukaryotic cells in large quantities for the manufacture of biotechnological
products like antibiotics, vaccines, enzymes, etc.
3. The techniques of genetic engineering include the following:
(i) Creation of recombinant DNA by combining desired genes.
(ii) Gene transfer.
(iii) Maintenance of DNA in host and gene cloning.
The basic steps in genetic engineering can be summarised as:
(i) Identification of DNA with desirable genes.
(ii) Introduction of the identified DNA into the host.
(iii) Maintenance of introduced DNA in the host hrtd transfer of the DNA to its progeny.
4. Construction of First Artificial Recombinant DNA
(i) It was achieved by linking a gene encoding antibiotic resistance with a native plasmid (an
autonomously replicating circular extrachromosomal DNA) of Salmonella typhimurium.
(ii) Stanley Cohen and Herbert Boyer accomplished this in 1972.
(iii) They isolated the antibiotic resistance gene by cutting out a piece of DNA from a
plasmid.
(iv) The cutting of DNA at specific locations was carried out by molecular scissors, i.e.
restriction enzymes.
(v) The cut piece of DNA was then linked to the plasmid DNA with the enzyme DNA ligase.
The plasmid DNA acts as vectors to transfer the piece of DNA attached to it.
(vi) When this DNA is transferred into E. coli, it could replicate using the new host’s DNA
polymerase enzyme and make multiple copies.
(vii) This ability to multiply copies of antibiotic resistance gene in E. coli was called cloning
of antibiotic resistance gene in E. coli.
5. Tools of recombinant DNA technology are as follow:
(i) Restriction enzymes (ii) Polymerase enzymes
(iii) Ligases (iv) Vectors
(v) Competent host organism.
6. Restriction enzymes or ‘molecular scissors’ are used for cutting DNA.
(i) Two enzymes from E. coli that were responsible for restricting the growth of
bacteriophage were isolated in 1963, one of them added methyl group to DNA and the other
cut DNA into segments. The later was called restriction endonuclease.
(ii) The first restriction endonuclease Hind II was isolated by Smith Wilcox and Kelley (1968).
They found that it always cut DNA molecules at a particular point by recognising a specific
sequence of six base pairs known as recognition sequence.