Water, Hydrogen, and Oxygen, and where we get our energy

 

The above equation is a simple way of showing what happens during photosynthesis. There are more detailed ways to show it. Photosynthesis is a complicated process, or processes. But, at its heart, it may be summarized simply.

As you know, there's a lot of water on the earth. As you also know, water consists of two elements, Hydrogen and Oxygen. As you may not know, the energy you need is intimately connected to water. I'm using energy to type this, and you are using energy to move your eyes as you read it. What's that got to do with water?

Our food comes from photosynthesis. Green plants absorb light, and produce various molecules that we use as food, such as starches, sugars, several vitamins, and proteins.

 Light energy is used to split water, and the Hydrogen split off is then available for the manufacture of Carbon-containing molecules, like glucose, food molecules, which can be stored, broken down to release energy, or moved to parts of the organism where they are needed. Some of the need is to release energy. Most foods you buy at a grocery store, or a restaurant, come with a calorie number. That number indicates the amount of energy you would expect to get if you ate and digested that food. The energy comes from energy-storing molecules, like glucose. The Carbon-containing molecules, which have Hydrogen added to the Carbon, may also be used to produce important molecules like enzymes, vitamins, hormones and proteins. (Oxygen, Nitrogen, Sulfur and other elements may be added to a Carbon-based structure.)

Organic molecules, like glucose, will burn. Burning uses Oxygen to carry on combustion. There is a process, used by nearly all organisms, called cellular respiration. That process also uses Oxygen to create water, and, in the process, releases energy for use in our cells. So, putting it very simply, photosynthesis uses light energy to break water, and cellular respiration puts water back together, and releases energy.

I'm bald-headed. So lots of light hits my head. My cells, like yours, have lots of water. So why doesn't that light, on my scalp cells, split water and make glucose? The answer is that various helping molecules, molecular tools, as it were, are necessary for photosynthesis to occur. These include chlorophyll and several enzymes, which I don't have in my scalp cells.

Isn't God great? Thanks for reading.