Genetic Engineering

                          Genetic Engineering 

    Genetic engineering or recombinant DNA technology involves the artificial synthesis, modification, removal, addition and repair of the genetic material (DNA). Genetic engineering developed in the mid-1970s when it became possible to cut DNA and to transfer particular pieces of DNA from one type of organism into another. As a result, the characteristics of the host organism could be changed. If host organism is a microorganism, such as a bacterium, the transferred DNA is multiplied many times as the microorganism multiplies. Consequently, it is possible to obtain millions of copies of a specific DNA inside a bacterial cell.

 Objectives of Genetic Engineering:

                                                            The important objectives of genetic engineering are as follows 

• Isolation of a particular gene or part of a gene for various purposes such as gene therapy. 

• Production of particular RNA and protein molecules .

• Improvement in the production of enzymes, drugs and commercially important organic chemicals .

• Production of varieties of plants having particular desirable characteristics .

• Treatment of genetic defects in higher organisms.

 Basic Steps in Genetic Engineering:

                                                             All the above mentioned objectives can be obtained by some basic methodologies, such as:

1. Isolation of the gene of interest:

                                                     In the first step, the genetic engineer identifies the gene of interest in a donor organism. Special enzymes, called restriction endonucleases, are used to cut the identified gene from the total DNA of donor organism.

2. Insertion of the gene into a vector:

                                                          A vector is selected for the transfer of the isolated gene of interest to the host cell. The vector may be a plasmid (the extra-chromosomal DNA present in many bacteria) or a bacteriophage. The gene of interest is attached with the vector DNA by using endonuclease (breaking enzymes) and ligase (joining enzymes). The vector DNA and the attached gene of interest are collectively called Recombinant DNA.

3. Transfer of recombinant DNA into host organism:

                                                                                   Recombinant DNA is transferred to the target host. In this way, host organism is transformed into a genetically modified organism (GMO).

4. Growth of the GMO:

                                    The GMO are provided suitable culture medium for growth to give as much copies of the gene of interest as needed.

5. Expression of the gene:

                                         The GMO contains the gene of interest and manufactures the desired product, which is isolated from culture medium.