My 165-pound body consists of about 110 pounds of oxygen, 30 pounds of carbon, 16 pounds of hydrogen, 6 pounds of nitrogen, and 3 pounds of everything else. Basic stuff, mostly, the stuff of water and air. You'd think we could get almost everything we need to build our bodies by taking deep breaths and gulps of water. But it's not quite that simple. Consider those 6 pounds of nitrogen in my body. Our cells build proteins by stringing together chemical units called amino acids, and every amino acid contains a nitrogen atom. Without nitrogen, no proteins. Without proteins, no me—and no tomato or bluebird; our bodies are tissues of proteins. So what's the problem? The atmosphere is 80 percent nitrogen. We suck in a lungful of nitrogen with every breath. But the nitrogen in the atmosphere (and in our lungs) is useless. The two nitrogen atoms in a nitrogen molecule are so tightly bound together that they are essentially inert; they hardly react with anything else. This inertness of nitrogen would seem to be a flaw in nature's Tinkertoy set, at least as far as life is concerned. We live in a sea of nitrogen, and it does us no good at all.
09 JUN 2011 by ideonexus