What biotechnology is

Biotechnology uses living organisms, or enzymes from them, to make products and processes useful to people. Making curd, bread or wine are old forms of it. Today the word mostly means work with genetically modified organisms to make products on a large scale.

Modern biotechnology rests on two core techniques:

• Genetic engineering: changing the chemistry of the genetic material (DNA or RNA), and putting it into a host organism to change what it makes.
• Bioprocess engineering: growing large numbers of only the wanted microbes or cells in sterile conditions, so that nothing else contaminates them, to make products such as antibiotics, vaccines and enzymes.

Why not just breed plants and animals the traditional way? Traditional hybridisation mixes whole sets of genes, so unwanted genes often come along with the desired ones. Genetic engineering moves only the gene you want.

But a piece of foreign ('alien') DNA put into a cell cannot multiply on its own. It must be joined to a DNA sequence called the origin of replication (ori), where copying begins. Then it is copied each time the host's DNA is copied, and passed on to the host's offspring.

The first recombinant DNA was made in 1972 by Stanley Cohen and Herbert Boyer. They cut out a piece of DNA carrying an antibiotic-resistance gene and joined it to a plasmid (a small, circular DNA) from Salmonella typhimurium. They cut with restriction enzymes ('molecular scissors') and joined with DNA ligase ('molecular glue'). They then put this plasmid into E. coli, where it was copied many times over: the gene had been cloned.

So genetically modifying an organism takes three basic steps:

• Identify the DNA with the desirable genes;
• introduce it into the host;
• maintain it in the host and pass it on to the host's offspring.