What Is Biotechnology? - Biotechnology and Your Health: Pharmaceutical Applications - page 16

are producing the desired protein. Now they have sets of cloned cells
that can be increased in number to create large amounts of the
desired protein product.
Using Whole Animals and Plants
Since the 1950s, scientists have been able to clone plants. You may
have cloned a carrot or onion plant in school, meaning that you
isolated a single cell from the root of an onion or carrot and grew
it, first in liquid in a dish to which you added nutrients to allow the
cells to increase in number, and then in plant hormones that made
the clump of cells develop into an entire plant with roots, stem, and
all. Because you started with a single cell, you cloned the plant,
and your cloned plant was genetically identical to the plant that
provided the starting cell. If you had transformed it by engineering
for a new protein in the gene before you put that cell in the culture
dish, you could have created a set of genetically engineered plants
able to produce the new protein. The vectors used for plants have to
suit the plant. One vector used for many plants is a plasmid from
a bacterium that causes a large growth, called a crown gall, in plants
(Figure 1.5). You may see these large masses on trees. To insert a
gene into a plant susceptible to the bacteria, scientists first remove
the genetic information from the plasmid that causes the large
growths, and replace it with the genetic information for the desired
protein. The plasmid is then put back into the bacteria, and the
plant cells are infected. Some plants cannot be infected with the
crown gall bacteria, so the genetic information has to be delivered
another way. One common method is to a use a gene-gun, a device
that “shoots” tiny metal spheres that are covered with the genetic
information into plant cells.
Animals
Researchers have also inserted foreign genetic information into mice,
rats, chickens, pigs, and sheep. An animal whose genetic information