Question

Define Recombinant DNA. Explain any two methods of introducing alien DNA into the host cell

Answer 1

The recombinant DNA technology emerged with the innovation of restriction enzymes. It happened in the year 1968 by a Swiss microbiologist Werner Arber.

Complete answer:
Recombinant DNA technology is a technique mainly used to transform the phenotype of an organism also called the host when a genetically altered vector is introduced and integrated into the genome of the organism. So, mainly, this process involves the introduction of a foreign piece of DNA structure into the genome which contains the gene of interest. This gene which is introduced is the recombinant gene and the technique applied is called the recombinant DNA technology. We can say that the technology used for producing artificial DNA through the combination of different genetic materials that is DNA from different sources is referred to as recombinant DNA technology. Recombinant DNA technology is prevalently known as genetic engineering.

Inserting the preferred gene into the genome of the host is not as easy as it sounds. It involves the collection of the desired gene for organization into the host followed by a selection of the ideal vector with which the gene has to be integrated and recombinant DNA formed.
In this way, the recombinant DNA has to be introduced into the host. And in the last, it has to be maintained in the host and accepted forward to the offspring.

Two main methods by which alien DNA introduced into the host cell
1. Electroporation:-
DNA is a hydrophilic molecule so it cannot pass through cell membranes. In turn, to force bacteria to take up the plasmid, the bacterial cells must be made competent to take up DNA. This is completed by treating them with a specific concentration of a divalent cation such as calcium, which increases the efficiency with which DNA enters the bacterium through pores in its cell wall. Recombinant DNA can be then forced into such cells by incubating the cells with recombinant DNA on ice followed by placing them briefly at 42⁰C and then putting them back on ice. This enables the bacteria to take up the recombinant DNA.
2. Microinjection:-
In this method, Recombinant DNA is directly injected into the nucleus of an animal cell.
3. Biolistics or gene gun:-
This is a method that is suitable for plants. Cells are bombarded with high-velocity micro-particles of gold or tungsten coated with DNA in a manner known as biolistics or gene gun.

Note: Recombinant DNA technology established important to the production of vaccines and protein therapies such as human insulin, interferon, and human growth hormone. And also used to produce clotting factors for treating hemophilia and in the development of gene therapy.