Page 244 - The Errors the American National Academy of Sciences

ow does the system of sight, which the NAS evolutionists gloss over
as being a simple structure, work? How do the cells in the retina
perceive the light particles that fall on them?
The answer to this question is rather complicated. When pho-
tons strike the cells in the retina, they activate a chain reaction,
rather like a domino effect. The first of these dominoes is a molecule called
"11-cis-retinal," which is sensitive to photons. The moment a photon strikes
it, the 11-cis-retinal molecule changes shape. This change also alters the form
of the protein "rhodopsin," which is linked to 11-cis-retinal. In this way,
rhodopsin becomes able to bind to another protein called "transducin."
Before reacting with rhodopsin, transducin is attached to another mole-
cule called GDP. When it binds to rhodopsin, it releases GDP and attaches to
another molecule called GTP. Two proteins (rhodopsin and transducin) and
one phosphate molecule (GTP) are now attached to one another. This entire
structure is known as "GTP-transducinrhodopsin." Yet, the process has barely
begun. The new compound GTP-transducinrhodopsin is now compatible with
yet another protein, called "phosphodiesterase," which is already in the cell.
This connection is immediately made. As a result of this, the phosphodiesterase
protein acquires the ability to split a molecule called cGMP, which is again al-
ready in the cell. Since this process is carried out by not just a few, but by mil-
lions of proteins, the level of cGMP in the cell falls rapidly.
What has all this to do with sight? In order to find the answer to this
question, let us have a look at the final stage of this interesting chemical reac-
tion. The drop in the density of cGMP within the cell affects the "ion channels"
in the cell. These are proteins that regulate the number of sodium ions in the
cell. Normally, the ion channel allows sodium ions to flow into the cell from
outside, while another molecule expels the unnecessary ions, thus creating a
balance. When the number of cGMP molecules falls, so does the number of
sodium ions. This quantitative change gives rise to an electrical imbalance in
the cell. This electrical imbalance affects the nerves connected to the cell, and
what we call an "electrical impulse" forms. The nerves forward these signals to
the brain, where what we refer to as "sight" is experienced. 1

242