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Creating Pharm Plants from Crop Plants
Making plants that produce medicinal proteins requires
a bit of genetic engineering. Genetic engineering involves transferring
DNA from one organism into another,  and
in the case of pharm crops, the genes that are transferred cause
the plant to produce a pharmaceutical protein.
Every cell in an organism -- be it animal, plant,
or bacteria -- contains DNA. DNA is the genetic blueprint that lays
out the code for producing proteins. Why do we care that living
organisms make proteins? Because, proteins drive all of the molecular
reactions and cellular activities that (assembled together) give
life to an organism.
By producing proteins, sequences of DNA -- known as genes -- confer
a trait that is observed in the organism. The trait could be eye
color, plant height, or the ability to produce an enzyme or antibody.
Genes that code for certain traits in one organism can be identified,
copied, and then inserted into the DNA of another organism. It’s
a tricky, complicated, sometimes hit-or-miss process, but when  done
successfully the result is that the recipient organism now expresses
the trait of the donor organism. In this way, a plant’s cellular
machinery can be re-directed into making proteins that normally
are produced only in animals, or humans.
So, pharm crops contain an added trait, and the trait they are
genetically engineered to produce is a protein that is used for
medical purposes. Thus, these plants become something of a biological
factory, cranking out
the raw medical substances that are further refined into drugs.
In most cases the biologic is obtained from the pharm plant through
a process of extraction -- grinding up the plant’s leaves
or seeds, and then purifying the protein into a usable form. In
some cases, however, the pharm plant expresses the drug in its fruit,
so that the medicine can be administered to people or animals by
having them eat the fruit of the pharm plant. These so-called “edible
vaccines” could dramatically change vaccination programs in
developing countries where access to medical supplies and trained
health care workers can be limited.
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