When we introduce a "single "transgene in the body then can this one gene can replace the function of the defected gene ,as this defected gene might be present in all body cells?
1 Answer
It depends how you introduce it and at what stage of development.
Explanation:
There are two basic ways to introduce a transgene. The first is by linearization of the gene and microinjection into a fertilized embryo at very early stages. In this way, the transgene gets randomly incorporated. This will not inactivate the endogenous gene, though - and you'll get expression of the wildtype gene (that is located on the proper chromosome) and the transgene (assuming they have the same promoter elements).
The other way is through homologous recombination. This basically places your transgene over the top of the endogenous wildtype gene, and you replace the endogenous gene function with that of your transgene. This has to be done at very early stages, too. The benefit of this is that your transgene is under the control of the wildtype promoter (in the proper location, too).
