Redefining Reality - The Intellectual Implications of Modern Science

The last step is to insert copies of the desired gene into the
target genome.
The process of cutting target DNA by restriction enzymes
leaves a few nucleotides hanging off the end, like a frayed pair
of jeans. These unpaired bases protruding from the missing
segment of DNA are called the “sticky ends.”
We know what bonds with the sticky ends because the bases in
want to add has the complement of the sticky ends. These bond
together, but the result is not quite stable. We need to smooth
out the DNA. For this, we use a ligase enzyme, whose purpose
is to repair DNA.
Following these steps, we are able to take genes from anywhere and
insert them anywhere else. We can create plants and animals with
properties they never would have otherwise had.
Mice make useful models in medical research; they are enough
like humans that observing how diseases progress in mice and how
medicines affect them allows us to make reasonable inferences
about the same factors in humans. Despite these similarities, the
poliovirus does not affect mice. But researchers have been able to
create transgenic mice with the appropriate genes to make them
susceptible to polio, giving us another weapon in the battle to
eradicate this disease from the planet.
We can also use recombinant DNA technology to create transgenic
plants and animals that will act as pharmaceutical factories. We can
splice into the genome of a banana tree the genes for producing
vaccines to protect people from hepatitis B or cholera. We can
splice genes into chickens so that the white of the chicken’s eggs
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