What: This is the commonest analogy on the web for this idea. It should be expanded a bit, but I'm not sure how. The neurotransmitters themselves, serotonin, acetyl-choline are the keys. They are released from one side of a synaptic gap. They diffuse, very rapidly across the gap and bind specifically with membrane proteins(locks) other side of the gap. There are millions if not billions of molecules diffusing across such a gap. Image a million(to mix this metaphor) bees flying between 2 straight parallel fences at the same time. This image is a good approximation for how neurotransmitters diffuse across a gap. The molecule as puzzle piece is a useful association. The 3-d shape of a molecule can vary tremendously. Look at serotonin molecule in the link. Visualize the molecule without the OH-- hydroxyl group on the left. It is now a different key with a missing tooth, that doesn't fit very well into it's designated lock.

Writer: Matthew James Flynn

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Date: Apr 29 2013 6:52 PM