(a) (b)FIGURE 101, The T4 bacterial virus is an assembly of protein components (a). The "head"
is a protein membrane, shaped like a kind of prolate icosahedron with thirty facets and jilled
with DNA. It is attached by a neck to a tail consisting of a hollow core surrounded fry a
contractile sheath and based on a spiked end plate to which six jibers are attached. The spikes
and jibers affix the virus to a bacterial cell wall (b). The sheath contracts, driving the core
through the wall, and viral DNA enters the cell. [From Hanawalt and Haynes, The Chemical
Basis of Life, p. 230.]
means, and then carefully ensures the manufacture of proteins which will
have the effect of destroying the virus itself! It is a sort of suicide-or
Epimenides sentence, if you will-on the molecular level. Obviously it
would not prove advantageous from the point of view of survival of the
species. However, it demonstrates the spirit, if not the letter, of the
mechanisms of protection and subversion which cells and their invaders
have developed.
E. Coli vs. T 4
Let us consider the biologists' favorite cell, that of the bacterium Escherichia
coli (no relation to M. C. Escher), and one of their favorite invaders of that
cell: the sinister and eerie T4 phage, pictures of which you can see in Figure
- (Incidentally, the words "phage" and "virus" are synonymous and
mean "attacker of bacterial cells".) The weird tidbit looks like a little like a
cross between a LEM (Lunar Excursion Module) and a mosquito-and it is
much more sinister than the latter. It has a "head" wherein is stored all its
"knowledge"-namely its DNA; and it has six "legs" wherewith to fasten
itself to the cell it has chosen to invade; and it has a "stinging tube" (more
properly called its "tail") like a mosquito. The major difference is that
unlike a mosquito, which uses its stinger for sucking blood, the T4 phage
uses its stinger for injecting its hereditary substance into the cell against the
will of its victim. Thus the phage commits "rape" on a tiny scale.
Self-Ref and Self-Rep^537