RECOMBINANT DNA TECHNOLOGY (CLONING):
You might say that recombinant DNA technology grew out of experiments with E.coli and the bacteriophages that infect
it. In the late 1960s and early 1970s, researches learned how to use a variety of cutting and splicing enzymes to make
DNA fragments and "package" them in plasmids for insertion into host cells.They developed ways to pinpoint the DNA fragments of interest in individual lines lines of dividing cells.They also started to identify the nucleotide sequences of individual genes and to sequence the genome.For different spaecies. The following eaxamples will give you a sense of what the new technology entails.
1) Restriction enzymes cuts chromosomal DNA at specific recognition sites.
2) Same restriction enzymes is used to cut plasmids.
3) Cut plasmid DNA and fragments of chromosomal DNA are joined using DNA ligase.
4) Recombinant plasmids containing cloned library. So we now have plasmids into which DNA fragments are spliced for
propagation in host cells. A plasmid or any other self-replicating genetic element used to insert DNA into a host cell
or propagation is called a cloning vector.Any collection of DNA fragments produced by restriction enzymes and incor
- porated into cloning vectors is called a DNA library.Each library contains DNA fragments from a single species only.