Question

How can foreign DNA be inserted into cells?

Answer 1

Insertion of foreign DNA:

Foreign DNA can be inserted into the host cell in two major ways -

1. Indirect gene transfer: In this method, a vector is used to insert the foreign DNA into the host cell. It generally occurs through:

• Viruses: Viruses are used where vectors are introduced into the virus which is then allowed to infect the cell.
• Plant tumours: In this process, the formation of the tumour is induced by using the soil bacterium Agrobacterium tumefaciens in which Ti plasmid is inserted.

2. Direct gene transfer: In this method, DNA is directly inserted into the cell of host organisms. This process occurs through:-

• Heart Shock: At 0° Celcius the cells are inoculated with vector in calcium ion solution and then it is suddenly heated to around 40° Celcius temperature. Due to this sudden heat shock, the membrane generates pore in them and thus the cells take up the vector.

• Gene gun: A foreign DNA coated with gold is tungsten particles is fired at cells with the help of a compressed air gun.
• Micro-injection: Using a very small micropipette foreign DNA is injected directly into the nucleus, puncturing the plasma membrane.