The Debate About Molecular
Machines
Living
things contain natural molecular machines that are made of many tiny
proteins. These machines have parts that are similar to parts in
man-made machines and that form a complex system. A bacterial motor
is an example of a molecular machine. It has 10 protein parts for the
sensor, 10 protein parts for the control circuitry, and 10 protein
parts to construct the motor. These proteins form parts such as
rotors, stators, drive shafts, O-rings, and bushings. All of these
proteins form a complex system that has multiple, separate,
well-matched parts that work together for a special function. A
bacterial motor is also irreducibly complex, which means each piece
must be present and fully functional in order for the system to work.
Opponents
of evolution claim that the presence of molecular machines
contradicts the idea of natural selection through mutation. The
characteristics of natural selection and the characteristics of
molecular machines are very different. Natural selection makes
gradual changes, but molecular machines must be fully formed in order
to work. Also, natural selection preserves small advantageous
changes, but a small piece of a molecular machine would not
provide an advantage, and therefore would not be preserved.
The
evolutionists attempt to explain molecular machines with an idea that
they call co-option, which involves the use of previously existing
parts to build a new machine. Those parts must be chosen, collected,
recombined, and reassembled. The evolutionists claim that natural
selection could build a complex structure by co-opting pieces of
simpler machines. They point out that the cellular pump includes 10
proteins that are also found in the bacterial motor, and that protein
parts can have multiple uses. Evolutionists conclude that since
protein parts have multiple uses, natural selection could assemble a
more complex machine from parts of simpler machines.
Opponents
of evolution point out 3 problems with the theory of co-option. The
first problem is that the random process of natural selection has
limits. There is no known way for a random process to co-opt pieces
without breaking the vital, previously existing system. There is also
no known way for a random process to guarantee that the randomly
chosen pieces will fit together well enough to work properly.
The
second problem is with the pump-to-motor example. The motor proteins
seem to be older than the pump, which means that the motor proteins
could not have been taken from the pump. Also, the motor has 20
proteins that are not similar to any proteins in the pump or proteins
in anything else, which means that those 20 proteins could not have
been co-opted from something else.
The
final problem is with the requirements for assembling proteins. The
bacteria would not only have to have genes to make the protein parts
of the motor, but would also need information to tell how to put the
proteins together. Another requirement is an irreducibly complex
machine to assemble the proteins. In trying to explain where one
complex machine came from, the evolutionists need to introduce
another complex machine. However, explaining the origin of one
machine with another does not sufficiently explain the origin of
machines. Looking at all of the evidence against the evolutionists'
theory of co-option, opponents conclude that it does not sufficiently
explain how molecular machines can be developed through natural
selection.
Oops, I thought there were more to the series. Guess this was the last one.
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