Recombinant DNA

Recombinant DNA (rDNA) molecules are DNA molecules formed by laboratory methods of genetic recombination (such as molecular cloning) to bring together genetic material from multiple sources, creating sequences that would not otherwise be found in the genome. Recombinant DNA is possible because DNA molecules from all organisms share the same chemical structure. They differ only in the nucleotide sequence within that identical overall structure.

Quotes

 * Use of restriction enzymes and recombinant DNA methods allowed resolution of a long standing and central issue in immunology, the genetic origin of antibody diversity. It turned out that an organism does not inherit even a single complete gene for antibody polypeptide chains. Rather, the genetic information is transmitted in germline as no more than several hundred gene segments.
 * Susumu Tonegawa, Nobel Lecture (1987)