In the last 50 years, a revolution has occurred in biology.
It's become possible not just to observe the cell, but to manipulate it.
And alter the genetic code of life itself.
Scientists can cut out a gene from any organism, and insert it into the DNA of a completely unrelated species.
This astonishing procedure is called genetic modification.
Genetic Modification – GM
Because DNA is shared by all living cells, the new gene can still function in the foreign cell.
It means that proteins normally only made in fish can be inserted into plants. Or human proteins can be manufactured by bacteria.
These new techniques have enormous potential, but genetic modification has been extremely controversial.
Genetic modification has changed our world.
One of the first breakthroughs was to use bacteria to grow human insulin - needed to treat people with diabetes.
The human gene for insulin production is cut out using enzymes, and inserted into a small piece of DNA called a plasmid.
This round plasmid is then inserted into the bacterium.
Because bacteria reproduce quickly, they produced human insulin in vast quantities.
Similarly, the genetic modification of crop species had amazing potential for agriculture.
Tobacco can be engineered to glow when it needs water.
Genetically modified maize can withstand drought.
And GM potatoes can resist pests.
For thousands of years we've been altering the genes of plants by traditional breeding techniques - eliminating weaker strains through selective breeding, or crossbreeding of different species.
But the key difference is that GM potentially allows us to break all species barriers, allowing us to manipulate the genetic code of all life on Earth.