The Most Important Chemical Equations

I've become a chemistry geek in my old age.  It's surprising because I hated chemistry in college.  These days I'm busy memorizing the first few lines of the periodic table.

I certainly don't expect most people to share my love for chemistry, but there are two equations that I wish that everyone knew, because all human life and almost all life on earth depends on them.  I have written about the equations before (in posts on Biology 101: Photosynthesis, 5/17/12, and Biology 101: Cellular Respiration, 5/10/12) but this is important, and it's been a while, and I'm hoping this post will tie some of this together.  I also hope to build on this in upcoming posts.

The first equation is the one for photosynthesis: 6 CO2 + 6 H2O (+ sunlight) → C6H12O6 + 6 O2

This means that a plant uses six molecules of carbon dioxide and six molecules of water as well as the energy of the sun to create a molecule of sugar (glucose--C6H12O6) and six molecules of oxygen.  It's an elegant equation.  You can count the carbons (C), hydrogens (H), and oxygens (O) and there's the same number on each side of the arrow.

Basically plants suck carbon dioxide out of the air and (along with water) use it to build sugars--and from there build themselves (plant walls are made of cellulose which is made from long chains of glucose strung together).  When you look at a towering tree, you are looking at something built mostly out of carbon dioxide and water.  On a planet facing climate disruption because there is too much carbon dioxide in the atmosphere, more plants and more trees are a big part of the answer.

There is a second, equally important equation that explains why we and most life exists.  It's the equation for cellular respiration, which is the process that cells (including our cells) use to function, and therefore it's the process that keeps us alive.  And it's exactly the reverse of the equation for photosynthesis:
C6H12O6 + 6 O2 → 6 CO2 + 6 H2O (+ energy)

What this says is that, in order for our cells to get the energy they need to survive, they use oxygen and food (broken back down into glucose).  This is why we need to breathe and eat.  And the process of cellular respiration gives off carbon dioxide and water (which we exhale and pee out of us).

Notice that plants (during the day) give off oxygen and store sugar which is what we need to survive, and we give off carbon dioxide and water, which is what the plants need for photosynthesis.  It's a perfect circle.  And all of us are totally dependant on plants for oxygen (plants are the reason for the oxygen in the atmosphere) and the sugars (etc) we need for energy.

All the carbon in our bodies comes from plants--directly or indirectly.  Even an extreme carnivore who eats nothing but carnivores is dependent on plants (someone somewhere along that food chain eats an herbivore that eats plants), because almost all animals (and fungi, for that matter) can't photosynthesize and need to get their carbon from plants which can.

So study these equations and thank a plant for your life.  Plants are what make the world sustainable.


Quote of the Day: "We cannot cheat on DNA. We cannot get round photosynthesis. We cannot say I am not going to give a damn about phytoplankton. All these tiny mechanisms provide the preconditions of our planetary life." - Barbara Ward