Biology 1002B Lecture Notes - Lecture 82: Irreducible Complexity, Ontogeny, Biogeography
20 Apr 2016
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Hard to tell this is an organ, not a single gene or protein. Eye is a classic argument for irreducible complexity idea that very complex systems couldn"t have evolved from something more simple. Counterargument simpler systems that use light for information (ex. eyespot in chlamy) Pax6 codes for a transcription factor (regulatory mechanism) that is the master controller of eye development: knock out pax6 no eye development. Evolved very early: found in many organisms; with different types of eyes, found even in organisms that don"t actually develop eyes (used to have a different function) Many pax6 homologues: highly conserved areas in homologues functionally important. All eyes have crystallins (proteins) but cyrstallins are not homolgous. In vertebrates crystallin proteins make up the lens (refracts light: homologous to heat-shock protein (crystallins arose through hsp-gene duplication) Crystallins prevent protein clumping as do hsps. In other organisms not hsp-like: arose through tinkering with other genes.
