the theory of evolution is unable to overcome with regard
to the development of a single protein are not limited to
those we have recounted so far. It is not enough for amino
acids to be arranged in the correct numbers, sequences, and
required three-dimensional structures. The formation of a
protein also requires that amino acid molecules with more
than one arm be linked to each other only in certain ways.
Such a bond is called a "peptide bond." Amino
acids can make different bonds with each other; but proteins
are made up of those-and only those-amino acids which are
joined by peptide bonds.
A comparison will clarify this point. Suppose
that all the parts of a car were complete and correctly assembled,
with the sole exception that one of the wheels was fastened
in place not with the usual nuts and bolts, but with a piece
of wire, in such a way that its hub faced the ground. It would
be impossible for such a car to move even the shortest distance,
no matter how complex its technology or how powerful its engine.
At first glance, everything would seem to be in the right
place, but the faulty attachment of even one wheel would make
the entire car useless. In the same way, in a protein molecule
the joining of even one amino acid to another with a bond
other than a peptide bond would make the entire molecule useless.
Research has shown that amino acids combining
at random combine with a peptide bond only 50 percent of the
time, and that the rest of the time different bonds that are
not present in proteins emerge. To function properly, each
amino acid making up a protein must be joined to others only
with a peptide bond, in the same way that it likewise must
be chosen only from among left-handed forms.
The probability of this happening is the same
as the probability of each protein's being left-handed. That
is, when we consider a protein made up of 400 amino acids,
the probability of all amino acids combining among themselves
with only peptide bonds is 1 in 2399.