What are the different methods of contraception?

Explanation

There are several methods of introducing the ligated DNA into recipient cells. Recipient cells after making them competent to receive, take up the DNA present in their surrounding. R-DNA can be forced into such cells by incubating the cells with r-DNA on ice followed by placing them briefly at `42^(@)C` (heat shock) and then putting them back onice. This enables the bacteria to take up the r-DNA.
In Micro-injection method, r-DNA is directly injected into the nucleus of an animal cell. In Bio listic or gene gun method - cells are bombarded with high velocity micro particles of gold or tungsten coated with DNA.
In another method, .Disarmed pathogen. vectors are used which when allowed to infect the cell, transfer the r-DNA into the host.