BIOLOGY September 16, 2013
-1.3 Light as a source of information
-photoreceptor basic light-sensing system, found almost universally in all organisms
-Phodopsin is the most common photoreceptor in nature
-basis of vision in animals
-also used by many organism
-Rhodopsin: a highly conserved photoreceptor
-consists of a pigment molecule (retinal) bound to a protein (opsin)
-sensing light without eyes
-allows sensing of light direction and intensity
-organism responds by phototaxis
-What distinguishes the eye of a simple invertebrate from the eyespot of the green algae C.
-Requires a brain to interpret signals sent from eye – Co-evolution
Darwin and the Evolution of the Eye-
-Darwin is the most important biologist there ever has been.
“if numerous gradations from a simple and imperfect eye to one complex and perfect can be
shown to exist”.
-variation is REQUIRED for evolution to occur.
Evolution of the Eye
-camera eyes evolved by variation and natural selection from a simple primitive eye
-improved eyes give a huge advantage to organism
-read sections on different types of eyes and eye evolution (sections 1.3c and 1.3d)
-PBS VIDEO ON THE EVO OF THE EYE