DNA taken from both the sources is fragmented by restriction endonuclease.
The restriction enzyme cuts both molecules at the specific site.
The ends of the cut have an overhanging piece of single-stranded DNA called "sticky ends."
These sticky ends are able to base pair with any DNA fregment that contains the complementary sticky end.
Enzyme DNA ligase is used to covalently link the two strands into a molecule of recombinant DNA.
This recombinant DNA needs to be replicated many times (i.e. cloned).
Cloning can be done in vitro, via the Polymerase Chain Reaction (PCR), or in vivo (inside the cell) using unicellular prokaryotes (e.g. E.coli), unicellular eukaryotes (e.g. yeast), or mammalian tissue culture cells.
Examples of the therapeutic products made by recombinant DNA techniques
