Tuesday, September 1, 2009

The Carbon Connection

“Only connect!... Only connect the prose and the passion and both will be exalted, and human love will be seen at its height. Live in fragments no longer. Only connect...” E. M. Forster

What do we mean when we say that life is an interdependent web? Partly it's a metaphor that points to the way that living things make up of a vast network of interrelations. How are living things connected? All life-forms are made from the same types of molecules: water, proteins, carbohydrates, lipids, DNA, and RNA; All life forms metabolize energy with the help of enzymes made from amino acids; All life-forms share a common ancestor, according to Darwin's theory of evolution; All living things ultimately depend on the Sun's energy; All living things share materials and substances that are only available on Earth; All living things interact cooperatively and competitively with other living things.

All well and good, but what makes this vast and intricate global interdependence possible? If I was to pick one thing it would be the element Carbon. You may recall that I said in the previous article that each element is a kind of character. Carbon is the most extroverted sociable element there is. He is an exceptionally friendly fellow. He makes bonds with everybody and they are often strong bonds called covalent bonds that require more energy than the other two kinds of bonds to break apart. Diamonds, the hardest substance known, are made from pure carbon bonded covalently.

OK, lots of elements bond covalently, but what differentiates Carbon from everyone else is that he can't get enough of himself. Carbon loves to bond with himself and does it over and over in chains, and in rings, in two dimensional sheets and in three dimensional tetrahedons. There is literally no end to the number of carbon atoms that can join together to form chains of fantastically diverse lengths.

And Carbon is a multi-tasker extraordinaire. So while he's linking up to carbon copies of himself, he's always socializing with the other elements on the side, especially with Oxygen,Hydrogen and Nitrogen. These chains of carbons with various side links then form the backbones for literally all the molecules of life: the proteins, enzymes, carbohydrates, fats, etc... It's the incredibly complex shapes that are created by carbon bonds that are the key to life.

Life is autopoietic - it maintains itself over time. But in order to maintain itself a living organism must perform many functions , all of which require a vast variety of different kinds of molecules and only Carbon makes that possible .

But that's not all, because Carbon, in the form of carbon dioxide, is essential in regulating Earth's surface temperature and the acidity of the ocean and our bodies. These are big jobs and somebody's got to do them, or life as we know it would cease to exist. So why Carbon?

You'd think that a substance that makes up only .03% of the Earth's atmosphere would hardly be up for the job, but it's the size of the molecule that matters when it comes to the greenhouse effect. And carbon dioxide with three atoms, one Carbon and two Oxygen, is a bigger molecule than the two other main components of the atmosphere – Nitrogen and Oxygen - which each form molecules of only two atoms each. Note that water and methane, which are also bigger sized molecules are even more potent greenhouse gases than carbon dioxide but they don't remain in the atmosphere as long as carbon dioxide does, so their effect is smaller.

We think of carbon dioxide as being the bad guy because of global warming but in actual fact without carbon dioxide the Earth would be a ball of ice. It's just that our industries and transportation systems are producing too much carbon dioxide right now. But that's for another article.

When carbon dioxide dissolves in water it forms a weak solution of carbonic acid and bicarbonate which together makes it a buffer. Chemical buffers keep the pH of a solution more stable by neutralizing acids and bases, thus keeping the ocean and our blood at near constant pH. But if too much carbon dioxide is dissolved in water then it loses it's buffering quality and becomes an acid. When that happens in our blood stream we die from acidosis. The thing is, the metabolic reactions that sustain life only occur in a narrow range of temperatures and pH, so Carbon's role in regulating temperature and ocean pH is vital to life. The problem is when too much carbon gets into the atmosphere both those systems go out of whack and then we get into trouble.

When you think about it, we take Carbon for granted. Carbon has got a lot of responsibility for supporting life as we know it . We oughta give him some slack instead of making his job harder. After all, he's kinda like that guy Atlas, the one who holds up the sky in Greek mythology. Maybe somebody should write a book about him – a “green” Atlas Shrugged.

1 comment:

  1. Well done. This is an excellent piece that makes some complex interactions very easy to understand not to mention fun to read. Thx, Jen