What is Genetic Engineering?: Introduction, Mechanism

What is Genetic Engineering?: Introduction, Mechanism

Beginning of Genetic Engineering

1. For DNA recombination in genetic engineering, it is necessary to first break the DNA molecules into fragments. Till 1970, scientists did not have knowledge of this method.
2. Then in 1970, Nathans and Smith isolated an enzyme from bacteria of the genus Haemophilus influenzae that could break down the DNA molecule. This enzyme was called Restriction endonuclease enzyme. For this discovery, Nathans and Smith received the Nobel Prize in 1978.
3. Bacteria synthesize this enzyme to protect themselves from the ill effects of bacteriophage viruses that infect them.
4. This enzyme destroys the DNA molecule of the virus by cutting it like a scissor as soon as it enters the bacteria.
5. Within a few years after Nathans and Smith's discovery, the presence of a variety of other restriction endonuclease enzymes in many different species of bacteria was discovered.
6. By breaking the DNA molecules into small pieces by these enzymes and with the help of DNA ligase enzymes, It became possible to form recombinant DNA molecules by joining one or more segments of one DNA molecule to segments of other DNA molecules.

Thus, with the discovery of Restriction endonuclease enzymes, the foundation of Genetic engineering was laid in the 1970s.

Mechanism of genetic engineering and its sequential steps

1. The mechanism of action of genetic engineering, that is, Recombinant DNA technology, is quite complex. In this, the organism whose DNA is studied or used is called donor organism.
2. In its basic process, first of all, all the DNA molecules of the genome of the donor organism are separated and broken into such small segments, each of which can contain one to many genes.
3. Then after locating the desired gene, the section in which it is present is connected to such a small DNA molecule of any other organism in which a cell has the ability to self-duplicate independently. This small DNA molecule is called carrier or vector DNA molecule.
4. The carrier DNA molecule becomes recombinant DNA by binding to the donor DNA segment.
5. The first recombinant molecule was prepared by Paul Berg in 1972. In the form of carrier DNA molecules, mainly plasmids located in the cytosol outside the nucleoid of some species of bacteria or DNA molecules of some types of viruses are used.
6. Now by introducing the recombined DNA molecule into a bacterium, new proteins start forming in the bacterium and in this way, the transformation of the bacterium takes place.
7. By cultivating this modified bacterium in the culture medium, by proliferation, millions of colonies can be formed, which are called DNA clones. By this method, a protein under the control of a desired gene can be produced on a large scale, or the genome of a donor organism can be manipulated by introducing Recombinant DNA into the cells of the donor organism.

DNA-Library : By the above method all the fragments of DNA molecules of a species can be recombined with different carrier DNA molecules and their separate clones can be made. A collection of such clusters is called a DNA collection. They can be used in various research experiments as per the requirement.

Sequential Steps of Genetic Engineering

As per the above description, the methodology of genetic engineering can be divided into the following sequential steps –

1. Isolation of Desired Gene
2. Selection of Vector DNA Molecule
3. Insertion of Desired Gene into Vector DNA Molecule, producing a Recombinant DNA Molecule.
4. Cloning of Recombinant DNA

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