I will praise thee; for I am fearfully and wonderfully made: Psalm 139:14
"Biochemist Michael Behe has shown that even a ‘simple’ light-sensitive spot requires a dazzling array of biochemicals in the right place and time to function. He states:
"--When light first strikes the retina a photon interacts with a molecule called 11-cis-retinal, which rearranges within picoseconds to trans-retinal. (A picosecond [10-12 sec] is about the time it takes light to travel the breadth of a single human hair.)
--The change in the shape of the retinal molecule forces a change in the shape of the protein, rhodopsin, to which the retinal is tightly bound.
--The protein’s metamorphosis alters its behavior. Now called metarhodopsin II, the protein sticks to another protein, called transducin. Before bumping into metarhodopsin II, transducin had tightly bound a small molecule called GDP. But when transducin interacts with metarhodopsin II, the GDP falls off, and a molecule called GTP binds to transducin. (GTP is closely related to, but different from, GDP.)--GTP-transducin-metarhodopsin II now binds to a protein called phosphodiesterase, located in the inner membrane of the cell.
--When attached to metarhodopsin II and its entourage, the phosphodiesterase acquires the chemical ability to ‘cut’ a molecule called cGMP (a chemical relative of both GDP and GTP).
--Initially there are a lot of cGMP molecules in the cell, but the phosphodiesterase lowers its concentration, just as a pulled plug lowers the water level in a bathtub."
CMI
