What Is Biotechnology? - Biotechnology and Your Health: Pharmaceutical Applications - page 8

the triplet code for that amino acid, lines up the amino acid by base
pair formation with the mRNA on the ribosome. A cell protein then
connects the amino acids lined up by the mRNA. In this way,
the sequence of bases, taken in threes, determines the sequence of
a protein. A gene is thus the sequence of DNA bases that codes for
a protein.
The sequence of bases (the order of As, Ts, Cs, and Gs) in a gene
or a whole organism can provide useful information, including
details that are needed to move a gene from one organism to
another, and insight into how the cell decides to make the protein
encoded in the DNA and how the cells in an organism work
together. The sequence even provides clues about how different
organisms are related in evolution. Modern biotechnology is
only one way that scientists are using this information, and the
healthcare applications described in this topic are only one part of
modern biotechnology. Before we dive into the ways biotechnology
can be applied to your health, we have to become familiar with the
“biotechnologist's toolbox.”
THE BIOTECHNOLOGIST'S TOOLBOX
How to Engineer a Gene
The essential task of modern biotechnology is to change an organ-
ism's genetic material (DNA) to allow for the production of a useful
protein. The gene for the protein must first be isolated and engineered
so that it will drive production of the protein. The product may be the
protein, or it may be a modified organism, such as a bacterium that
cleans up oil spills, a tree that removes mercury from contaminated
soil, or a virus that treats cancer.
To isolate a gene, scientists use surgical DNA “scissors” called
restriction endonucleases ( RE ), proteins made by bacteria that cut
DNA, based on specific rules. Each kind of RE—there are hundreds—
recognizes specific sequences of 4-8 base pairs and cuts the DNA
molecule at a specific spot (Figure 1.2). The biotechnologist selects