Burn Baby Burn

When we eat a plant or an animal who has eaten a plant (or an animal who has eaten another animal who has eaten a plant), we are taking in potential stores of energy in the form of the chemical bonds holding together that organism’s molecules. Molecules are made of atoms. Atoms are composed of a nucleus with electrons orbiting around. Atoms can share electrons with each other, and this sharing holds the atoms together. This is a chemical bond. These bonds are potential sources of energy, since energy is released if the bonds are broken.

The forms of molecules that we can break down and use as fuel are carbohydrates (sugars), proteins, and fats. Every natural thing we eat contains some combination of those types of molecules. We begin by breaking these down, in the process of digestion, into smaller constituents. For example proteins are broken down into the amino acids of which they are composed, large sugars into small sugars, fats into simple fatty acids. Absorbed through the wall of our gastrointestinal tract, these simpler molecules are transported into our cells and become the building blocks of our own proteins, fats and sugars, or they are broken down further and fed into a cellular furnace which extracts the energy from their chemical bonds.

Each of these three classes of molecule begins its journey to the furnace in a different way, but eventually each is converted into the same kind of molecule that can enter a common pathway for complete breakdown and release of its energy. The furnace analogy is more than just apt, since the process of breakdown of these molecules is in fact combustion. That is, a process in which a carbon-based substance whether it be a sugar or petroleum or paper, in the presence of oxygen, is broken down, releasing energy and creating carbon dioxide and water in the process.

Now, in a fire the process is fast and out of control. In the cell by contrast, the process takes place in a stepwise and orderly fashion so as to best utilize the energy released. In a fire, all the energy is lost as heat and light. In our cells, some heat is lost (which is why we shiver—to generate heat by increasing the metabolism in our muscle cells), but some is converted into a storage form useable by our cells for its energy needs.

Basically, the energy released from breaking the bonds between the carbon atoms in these ingested molecules is used to kick an electron up hill in such a way as to capture the energy it releases as it rolls back down. This energy is converted into the bonds of a molecule called ATP–the universal energy molecule for all life, from a bacterium to a redwood.

So how does oxygen fit in? Well, that rolling electron needs somewhere to end up. The oxygen sits at the bottom of the hill waiting to catch the electron as it arrives. At the bottom, a complex system donates that electron to an oxygen atom and converts it harmlessly into water. Harmless is the key. Remember we said atoms have a nucleus with electrons in orbit around. We also said electrons can be shared between atoms, which forms a bond between them. This sharing is actually the result of a key property of atoms. They will always tend to their most stable state. Atoms that have all their orbiting electrons in pairs are very stable. Unpaired electrons create instability, and an atom like this tends to rectify the situation by pairing up with a similarly unstable atom with its own extra electron problem. They put their electrons together to make one happy, stable pair. That is why for example oxygen gas is O2 and not O. It is stable when paired with another oxygen atom.

So when that electron rolls down to oxygen, that oxygen atom now has an unpaired electron. A mechanism is set up to deal with this by linking on two hydrogen atoms and thereby forming a nice stable water molecule. Yet, as an electron is rolling down towards this elegant complex, it can occasionally leak out of the system early, pairing with oxygen outside the safe, water producing complex at the end. Now you have created superoxide, an unstable oxygen with an unpaired electron, that is, a free radical. To find stability it will look for a way to pair that electron. One possibility is to strip an electron from (or, oxidize—hence oxidant) another molecule in the cell (say DNA) and render it harmfully changed or non-functional. These free radicals are therefore extremely toxic. In fact, a type of cell in the immune system purposely creates superoxide and uses it as a weapon against foreign microorganisms.

Our cells contain an enzyme which cruises around and deactivates these free radicals as soon as they are formed. But no system is perfect and small amounts of damage are done to our cells. This damage is minimized by the presence of certain substances, like vitamins A, C, and E. They react with free radicals (are therefore anti-oxidants) and pull them out of circulation.

We break the bonds of organic (carbon containing) molecules, in the presence of oxygen and create ATP which our cells can use for all their activities, and carbon dioxide which is a waste product. The oxygen and carbon-containing molecules come ultimately from plants, who also process the carbon dioxide we produce. Our lungs absorb oxygen, and release carbon dioxide, while the collective lung of the green plants does the opposite.

Wouldn’t it be great if we as humans could manage to elect leaders who are committed to slowing the accelerating destruction of this elegant balance? Rather than those who would sell out the future of our planet in the interest of greed, hubris, and arrogance? Wake up! Our world is being destroyed. It’s not subtle. Vermiculture baby!

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Published in: on January 30, 2007 at 11:55 am  Comments (3)  

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3 CommentsLeave a comment

  1. You explained that very clearly. Maybe you should be a science writer.

    “Wake up! Our world is being destroyed.”
    You got that right. And we’re going down with it. Doesn’t anyone care?

  2. Thank you. I do enjoy writing about science. And I don’t mind the occasional tirade either.

  3. seems to me to be where the only true dependable energy can come from.

    Thanks,

    Smoky


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