Page 158 - Design in Nature

156 DESIGN IN NATURE

The Bacterial Flagellum
Some bacteria use a whip-like organ called a “flagellum” to move about
in a liquid environment. This organ is embedded in to the cell membrane
and enables the bacterium to move at will in a chosen direction at a
particular speed.
Scientists have known about the flagellum for
some time. However, its structural details, which have
only emerged over the last decade or so, have come as
a great surprise to them. It has been discovered that
Sperm cells, too, use a flagellum
the flagellum moves by means of a very complicated
in order to move about.
“organic motor” and not by a simple vibratory
mechanism as was earlier believed.
The propeller-like engine is constructed on the same mechanical
principles as an electric motor. There are two main parts to it: a moving part
("the rotor") and a stationary one ("the stator").
The bacterial flagellum is different from all other organic systems that
produce mechanical motion. The cell does not utilise available energy stored
as ATP molecules. Instead, it has a special energy source: bacteria use energy
from the flow of ions across their outer cell membranes. The inner structure
of the motor is extremely complex. Approximately 240 distinct proteins go
into constructing the flagellum. Each one of these is carefully positioned.
Scientists have determined that these proteins carry the signals turning the
motor on or off, form joints to facilitate movements at the atomic scale, and
activate other proteins that connect the flagellum to the cell membrane. The
models constructed to summarise the working of the system are enough to
depict the complicated nature of the system. 53
The complicated structure of the bacterial flagellum is sufficient all by
itself to demolish the theory of evolution, since the flagellum has an
irreducibly complex structure. Even if one single molecule in this fabulously
complex structure were to disappear, or become defective, the flagellum
would neither work nor be of any use to the bacterium. The flagellum must
have been working perfectly from the first moment of its existence. This fact
again reveals the nonsense in the theory of evolution's assertion of “step by
step development”.