Just recently had to have a spare key made, twice, since the first one was just slightly off, rendering it useless. And for those who know me well, this won’t surprise you, but it got me thinking about biochemistry. Organisms have an incredible system of energy saving – with both on/off switches for chemical reactions at key steps along the way; and with a lock and key type of signaling system.
In the first system, if there is too much or too little of a particular product somewhere in the process, it either stops or starts the entire cycle. Like any switch, it breaks the connected circuit temporarily. This sytem is more complicated, and isn't easily disrupted.
In the case of the lock & key – it has to be a key that fits exactly into the lock or it doesn’t open or close. Chemists know that it doesn’t matter how fancy or simple the key is designed, as long as the “business end” fits correctly. In terms of risk – if it doesn’t fit, it’s not a problem, no matter how much you are exposed to. However, if it fits, there is a concern, and protecting that target key from coming in contact with the lock becomes the concern.
So, when worrying about exposure to a chemical – two things have to be considered: one, how well does the key fit in a lock; and two, if it fits, what are the chances it come in contact with the lock?
