Biological Energy

Once upon a time I read a science fiction story about a solar system with three suns.  It had a single planet, constantly bathed in intense light.  It managed to generate a simple life form: a mindless little creature, happily converting sunlight into motion.  But when an astronaut’s shadow fell across it, it instantly collapsed.  Never having known a time without endless sunlight, it had never had to develop a method for storing energy.

Not so the inhabitants of this planet.  Our primary source of energy, the sun, comes and goes as our planet rotates.  Hence our single-celled ancestors faced a problem we still confront today:  how to store and transport energy.

The first unicellular organisms, which appeared something over 3.5 billion years ago, learned to combine light, water, and carbon dioxide and produce glucose and oxygen as products.  But they faced that light/dark problem.  In order to store and transport the energy involved, they created/invented/discovered that marvelous molecule, ATP.

ATP (adenosine triphosphate) is still the primary energy molecule of all life, including us.  Attaching phosphate groups to adenosine requires lots of energy.  By the time you’ve gone from adenosine to adenosine monophosphate (AMP) to adenosine diphosphate (ADP) to adenosine triphosphate, you’ve stored a ton of energy in this little molecule. Which make it very useful.

In a process called the Krebs cycle, what metabolism does is attach phosphate groups to ADP (storing away biological energy there), sends the ATP to where the energy is needed, strips off the phosphate group (liberating the energy), then sends the ADP back to repeat the process.  At any given time, every organism is just chock full of ATP.

And that also makes it ripe for stealing.

Imagine for a moment that you are a nice little unicell, happily floating in the primordial ooze.  You’re sucking up nutrients, absorbing sunlight, and making glucose.  You’re putting a lot of your energy (in both senses) into your ATP so you can produce that glucose for you to live on.

By chance, you often bump into your neighbors, who are hard at work doing the same thing you are.  Your neighbors, and, in fact, the whole world of life are pretty much just like you, except for one essential difference:

You are a budding economist.

Your neighbors are after the same resources you are, so it only make sense for everyone to avoid getting too close.  That way you don’t drain your personal environment of the things you both need.

Stay away?  Makes sense to everyone…but you.

You look at it differently.  Your neighbors are not just competitors for resources and a place in the sun.  Thanks to ATP, they are veritable repositories of all the things you are working so hard to acquire: nutrients, glucose, but, above all, energy.

So instead of avoiding your neighbor, you sidle right up to him…and engulf him.  You’ve now got twice as much – nutrients, glucose, and energy-packed ATP.

We’re not sure when and how all this began, but we know that ATP was almost certainly the key.  It supplied the energy for the theft as well as the target.  In fact, one could say that we, the descendants of this clever little unicell, are still doing the very same thing our ancestor did.  That is, it has been argued that the ultimate goal of all living things that eat other living things is to steal their ATP.

Nowadays, as the world tries to grow Green, we face the same problem (in a new form) –  energy storage and transport.   Take photoelectric generation: we use a lot of our energy at night, when the sun doesn’t shine.  Or wind generation:  who says we will only want energy when the wind is blowing.  Or, for that matter, who says we will want energy where the sun is shining or the wind is blowing.

When you look at short-range electric cars, the miserable life of your cell phone battery, or a hundred other problems, you get the same answer.  To date, we are much better at consuming energy than we are at storing it or transporting it.

It’s a return of that 3.5+ billion year old problem, the one our ancestors solved.  And, once again, solving it could be the key to our survival.

Who knows?  Maybe some biologically based alternative like ATP will be the answer.  Maybe it will be something else, something entirely new.  But we are confronting, however tardily, the essential problem of our energy efficiency.  I’d say we have a pretty good chance of solving it.

After all, we come from a long, long line of shrewd economists…or extremely clever thieves.

Assuming there’s a difference there.

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