Mathematical language is the translation for human understanding of reality itself. It is through complex equations that we have come to understand situations as intricate as relativity itself. But not only physics or quantum mechanics have mathematical expressions that are the full essence of their science, biology itself also has a very important equation with which life itself could be described.
Energy, carbon and electrons
Every being needs three factors that will endow it with life: a source of energy, a source of carbon, and a source of electrons. In this sense, photosynthesis is the clearest example that encompasses how the sum of abiotic factors through a series of processes make life possible. And although photosynthesis is not especially energy efficient, it is the ultimate form of self-sufficiency. Furthermore, the first organisms capable of oxygenic photosynthesis were the first to produce carbohydrates and oxygen from water and carbon dioxide. Thanks to them, the first Great Oxidation Event occurred, which later made complex life possible.
In that sense, the most important equation of biology is CO 2 + H 2 O → C 6 H 12 O 6 + O 2. (Its balanced version is: 6CO 2 + 6H 2 O → C 6 H 12 O 6 + 6O 2). Whose translation would be: carbon dioxide + water → glucose + oxygen. And while deceptively simple, it describes the process by which plants and photosynthetic organisms obtain their sources of vitality. And how, in turn, the result serves as food for complex life, including man. Namely, without the oxygen in the atmosphere, the human being would not have developed. There would probably be other forms of life very different from what we know, or it would simply not exist.
Behind the most important equation in biology
Within this equation, so important for biology, it can be seen how water is the source of electrons that plants need to start the photosynthetic process. When the light source (power) hit chlorophyll, this molecule gives up its electrons which will then trigger other amazing reactions. However, the chlorophyll molecule wants to get its electrons back, so it steals them from the water molecule, which ends up splitting into two protons (H+) and an oxygen atom. The oxygen atom is now alone and is not happy with it, so it finds a partner and associates with another oxygen atom, forming O2. The latter is the molecular form of the gas we breathe.
But that is only the beginning of the journey. Returning to the electrons donated by chlorophyll, these pass from one protein to another and as they travel through plant tissues, cause protons to be pumped to the membrane of the photosystem called the thylakoid. This action generates a powerful electrochemical gradient, as if it were a battery. However, just like your cell phone battery, this electrochemical gradient will deplete its power at some point. At that time and to counteract it, a molecule rich in energy called ATP is generated.
When the electrons that have been hopping from one protein to another finally finish their journey, are deposited in a molecule called NADPH. If NADPH had to be described as a human artifact, then it would be an electron catapult. Since it is capable of transporting them to where they are required with the purpose of building something else, through a process that experts know as the Calvin cycle.
Food for almost all forms of life
This cycle is the moment when another abiotic factor of great importance, carbon dioxide, joins the adventure. Right now carbon dioxide is transformed into a solid form which will then be combined with a five-carbon sugar. The result will be a six-carbon sugar called G3P, the building block of plant sustenance. Thanks to it, the plant can do a variety of processes. From generating your own food, to building structural molecules that help the plant grow.
Most of the life that shares this planet with us depends on photosynthesis. This process feeds its oxygen to aerobic beings that are completely dependent on it. Without the development of the process described in the photosynthesis equation we would simply not exist, which is why it is considered the most important expression of biology.
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