Processes of Recombinant DNA Technology — Definition

Definition

Imagine you want to take a specific instruction, let's say the instruction to make insulin, from a human cell and put it into a bacterial cell so that the bacteria can start making human insulin for us.

Recombinant DNA Technology (RDT) is the set of sophisticated biological tools and techniques that allow us to do exactly that. It's like a molecular cut-and-paste job. First, we need to carefully extract the entire genetic blueprint (DNA) from both the donor organism (human, in this case) and the recipient organism (bacteria).

Once we have the DNA, we use special molecular scissors, called restriction enzymes, to cut out the specific gene we're interested in (the insulin gene) from the human DNA. These same 'scissors' are also used to cut open a circular piece of DNA from the bacteria, called a plasmid, which will act as a vehicle or 'vector' to carry our gene.

The cut ends of the human insulin gene and the bacterial plasmid are designed to be complementary, allowing them to stick together. Then, a molecular glue, DNA ligase, seals these pieces, creating a new, hybrid DNA molecule called recombinant DNA (rDNA).

This rDNA, containing the human insulin gene, is then introduced into a bacterial cell. This process of introducing foreign DNA into a host cell is called transformation. Not all bacteria will take up the rDNA, so we need ways to select only those cells that have successfully incorporated the new genetic material.

These selected bacterial cells are then grown in large quantities in bioreactors. As these bacteria multiply, they also replicate the recombinant DNA and, crucially, start reading the human insulin gene and producing human insulin protein.

Finally, the desired protein (insulin) is extracted, purified, and processed for use. This entire sequence, from isolating DNA to obtaining the final product, constitutes the processes of Recombinant DNA Technology, a cornerstone of modern medicine and agriculture.