Redefining Reality - The Intellectual Implications of Modern Science

we could begin with the desired portion of the genome of one
organism and insert it into another. We can now do this with genes
of organisms of the same type, called cisgenic organisms. We can
also add in genes from quite different sorts of organisms, called
transgenic organisms.
transgenes, or genes
from other life forms, were bacteria. This experiment was
undertaken because it had already been done—by nature itself in
the form of bacteriophages.
Bacteriophages are a kind of virus that preys on bacteria. They
resemble a lunar landing module with six legs supporting a bulbous
pod. The pod is full of DNA. The phage lands on a bacterium and
hooks its landing gear into it, then drops the pod, piercing the
bacteria’s cell wall and injecting its DNA into the cell.
Some bacteria have two kinds of DNA that are separated in the cell.
First, there are the bacterial chromosomes that contain the DNA,
with the internal instruction manual for the cell to carry out its basic
functions. In addition, there are rings of DNA completely separate
from this, called plasmids. These code for proteins that may be
offensive or defensive; they might have the information for the
dirty work that makes the host of the bacterium sick, or they may
The reason bacteria develop immunities to antibiotics is that the
information about how to neutralize the antibiotic is stored in the
plasmids. Because the plasmids are distinct from the bacterial
chromosomes, they copy themselves. As such, there may be a
number of copies throughout the cell, and they are entirely distinct
from cell division. Sometimes, the divided cell splits up the
plasmids, sometimes not. As a result, the daughter cells may or may
not share the resistances of the progenitor cell.
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