Cool tidbit of knowledge

I have found Biochemistry, while a pain in the ass, to be extremely fascinating. The other day we learned how the chemistry of vision works. Since it was pretty damn cool I thought I would explain it the best I can in laymans terms.

Molecules can be connected in two different ways. One with that bulk of atoms on one side and one with the bulk on opposite sides. They are called cis and trans respectively.

Cis

Trans

How vision works is that it takes the aldehyde version of Vitamin A (Retinal) and combines it with another molecule called Opsin. This combined molecule, called Rhodopsin, is what is in the rod cells of the eyes.

When you absorb photons, i.e. look at something, it causes the one of the bonds in the Rhodopsin molecule to turn from trans to cis. It effectively is like turning a switch on and off. Maybe I'm geeky but I find it cool as hell that something that simple is what gives us the ability to see everything in our world. Ok, back to my chemistry book....