Recombinant dna technology-[how are specific genes chosen]??

[ARAVIND113122]

IN recombinant dna technology,certain segments of dna are removed from one organism and put in another.How are are specific portions of DNA removed from certain animals and fused into others?? More importantly,how do scientists know which portion of DNA regulates the desired trait-how can they figure this out when there are millions of base pairs??

[atyy]

A famous case is how a gene that makes you glow green was found.

http://gfp.conncoll.edu/prasher.html: Prasher's GFP work was funded by the National Cancer Institute. In his grant he suggested that it should be possible to take the GFP gene out of the jellyfish cell and attach it to cancer cells so that they would be labeled with a fluorescent tag. Prasher managed to find the gene for GFP in Aequorea victoria and was able to express it in bacteria. In 1992, he published a paper in Gene; it reported the cloning of GFP and the sequence of the 238 amino acids in GFP, shown below."

In that case the amino acid sequence was known, from which a portion of the gene sequence was guessed. The guessed sequence was chemically synthesized. The synthesized sequence would bind to the complementary portion of the full gene sequence in a "gene library".

Another way to do it is called expression cloning (http://en.wikipedia.org/wiki/Expression_cloning).

[mishrashubham]

If you are asking people know whether a given sequence is a functional gene or not, it is called Gene Prediction.
http://en.wikipedia.org/wiki/Gene_prediction