|Recombinant DNA technology was first used commercially to produce human insulin
from bacteria. In 1982, genetically engineered insulin was approved for use by diabetics.
People with certain types of diabetes inject themselves daily with insulin, a protein hormone
that regulated blood sugar.
Insulin is normally produced by the pancreas, and the pancreases
of slaughtered animals such as swine or sheep were used as a source of insulin.
(Click on the image to see it full size)
|To provide a reliable source of human insulin, researchers obtained
from the human cells of DNA carrying the gene with the information for making human insulin.
Researchers made a copy of DNA carrying this insulin gene and moved it into a bacterium.
When the bacterium was grown in the lab, the microbe split from one cell into two cells,
and both cells got a copy of the insulin gene.
Those two microbes grew, then divided into four, those four into eight, the eight into sixteen,
and so forth. With each cell division, the two new cells each had a copy of the gene for human
insulin. And because the cells had a copy of the genetic "recipe card" for insulin,
they could make the insulin protein. In the way, special strains of Escherichia coli (E. coli)
bacteria or yeast given a copy of the insulin gene can produce human insulin.