Page 283 - Darwinism Refuted

Harun Yahya (Adnan Oktar)

that is sensitive to photons. When struck by a photon, this molecule
changes shape, which in turn changes the shape of a protein called
"rhodopsin" to which it is tightly bound. Rhodopsin then takes a form that
enables it to stick to another resident protein in the cell called "transducin."
Prior to reacting with rhodopsin, transducin is bound to another
molecule called GDP. When it connects with rhodopsin, transducin
releases the GDP molecule and is linked to a new molecule called GTP.
That is why the new complex consisting of the two proteins (rhodopsin
and transducin) and a smaller molecule (GTP) is called "GTP-transducin-
rhodopsin."
But the process has only just begun. The new GTP-transducin-
rhodopsin complex can now very quickly bind to another protein resident
in the cell called "phosphodiesterase." This enables the phosphodiesterase
protein to cut yet another molecule resident in the cell, called cGMP. Since
this process takes place in the millions of proteins in the cell, the cGMP
concentration is suddenly decreased.
How does all this help with sight? The last element of this chain
reaction supplies the answer. The fall in the cGMP amount affects the ion
channels in the cell. The so-called ion channel is a structure composed of
proteins that regulate the number of sodium ions within the cell. Under
normal conditions, the ion channel allows sodium ions to flow into the cell
while another molecule disposes of the excess ions to maintain a balance.
When the number of cGMP molecules falls, so does the number of sodium
ions. This leads to an imbalance of charge across the membrane, which
stimulates the nerve cells connected to these cells, forming what we refer
to as an "electrical impulse." Nerves carry the impulses to the brain and
"seeing" happens there. 347
In brief, a single photon hits a single cell, and through a series of chain
reactions the cell produces an electrical impulse. This stimulus is modulated
by the energy of the photon—that is, the brightness of the light. Another
fascinating fact is that all of the processes described so far happen in no
more than one thousandth of a second. As soon as this chain reaction is
completed, other specialized proteins within the cells convert elements such
as 11-cis-retinal, rhodopsin and transducin back to their original states. The
eye is under a constant shower of photons, and the chain reactions within
the eye's sensitive cells enable it to perceive each one of these.

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