GENETIC ENGINEERING

GENETIC ENGINEERING

Genes act as instruction to make specific substances (proteins) which are used for specific structure and physiological purposes in the body. Genetic engineering is an advanced technique in biotechnology in which scientist select and isolate the useful gene form one organism (donor organism)and insert it into another organism (usually bacterium). The organism that contains a foreign gene in its cells is called transgenic organism. The inserted gene produce the desired product (proteins) in transgenic organism.

Importance of Bacteria in Genetic Engineering

The scientist use bacteria cell because it is very simple and easy to grow. It does not have an organized nucleus. The  chromosome, consisting of DNA, floats in the cytoplasm. Additional circular pieces of DNA plasmid are also present in the cytoplasm. plasmids can be easily isolate from a bacterial cell and gene can be attacked with it. Plasmids can carry the attacked foreign gene into the bacterium. In this way, plasmid act as a carrier of a foreign gene. Another reason for using bacteria in genetic engineering is their fast rate of reproduction.

Bacterial cells

Introduction of Gene  into Bacteria

The first step of  genetic engineering for inserting a gene into a bacterial cell is the identification and isolation of the gene of desired proteins from the donor organism see. An enzyme is used to cut the gene from the donor organism. The isolated gene is then attacked with plasmid DNA taken from a bacterium. The same enzyme (used for cutting the donor gene) is used to cut the plasmid DNA at a specific site so that the gene can be attacked at the cut end of the plasmid. The attacked gene of desired proteins and the plasmid DNA are collectively called recombinant DNA. The recombinant DNA is inserted back into the same type of bacterium from which the plasmid was isolated. The bacterium which takes in the recombinant DNA is called genetically modified bacterium (GM bacterium) or transgenic bacterium.

Introduction of gene into a bacterium

GM bacterium starts dividing and produce a bacterial colony. Every bacterium of the colony contain a copy of the gene of desired protein. When bacterial colony grows, it start making protein under the instruction of inserted gene.

In genetic engineering, genes of various useful protein, insulin, enzyme for the synthesis of various medicines, vaccines, are inserted in bacteria and desired proteins are obtained.