Redefining Reality - The Intellectual Implications of Modern Science

The second step is trickier. Here, we need to be able to remove just
the desired stretch of genetic information from the target DNA.
We want to isolate the replacement code to be inserted from the
organism whose property we are adding. The DNA molecules in
the chromosomes are long strands of base pairs. We need to know
exactly where and how to snip the chromosome.
The key here was the discovery of restriction enzymes. Bacteria
restriction enzymes cut up the invader’s rogue DNA before it can get
the stray genetic material, rendering the phage attack harmless.
The great discovery made by the Nobel Prize–winning
microbiologist Hamilton O. Smith was that some restriction
sections. These enzymes are triggered only by particular bits
of genetic information. They look for certain sequences of the
enzymes could be used more carefully by us to snip out exactly the
segments we want from a given genome.
Having the gene we want to insert and having the restriction enzymes
remove the bit we don’t want from the target chromosomes, we
now need to get the new DNA into the target. For this, we need to
copy it, using the polymerase chain reaction.
The polymerase chain reaction is a cyclical process for which
the American Kary Mullis received the Nobel Prize. It uses heat
to separate the strands of DNA. Next, a primer is added that
sticks to the separated strands in a way that creates a template
for the reconstruction of the full DNA molecule.
A polymerase is added that provides the nucleotides needed to
complete the process, and the separated strands are made into
two completely different strands of the same DNA.
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