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7.2 describe what is meant by ‘gene cloning’ and give examples of the uses of gene cloning
describe what is meant by ‘gene cloning’ and give examples of the uses of gene cloning
- Cloning is the production of a genetically identical gene, cell or whole organism. Gene cloning involves the production of many identical genes.
Human insulin, used by diabetics to control blood sugar levels, is now produced by the cloning of recombinant DNA.
- This process occurs by using special cutting enzymes, known as restriction enzymes, to cut out the gene for making insulin from a human chromosome. The enzymes are also used to cut open a plasmid in a bacterial cell leaving “sticky ends”. A plasmid is a circular piece of DNA within the bacterium. The sequence of bases in the open space in the plasmid matches the ends of the piece of human DNA. The human DNA is then inserted into the plasmid. The plasmid (now genetically engineered) is placed back into a bacterium and is reproduced every time the bacterium reproduces asexually.
- In this way, the human gene has been cloned. When given all of the required nutrients, these bacteria will produce human insulin according to the human genes they contain.
- In a similar fashion, gene cloning can be used for:
- breaking down toxic waste from oil spills,
- producing a protein that dissolves blood clots,
- introducing pest resistance in some plants like the cotton plant that is now resistant to the cotton boll weevil,
- immunisation against such diseases as cholera and typhoid.