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Cellular Respiration Formula

Cellular Respiration Formula

Cellular respiration is the fundamental process that sustains life at a cellular level. If you are looking for the reaction formula that sums it up, this article will definitely be a helpful read.
Omkar Phatak
Cellular respiration is one of the most basic processes, without which, life on Earth wouldn't have been possible. The energy that every organism requires to survive, is derived through this process at the cellular level.

What is Cellular respiration?

This process is a combined set of metabolic reactions that occur in every cell, that converts biochemical energy derived from food, into the energy currency of the body, which are ATP (Adenosine Triphosphate) molecules. It also involves the release of waste products.

The nutrients derived from foods like glucose, are the raw materials of cellular respiration. Carbohydrates or sugars are processed at a cellular level to create energy, that is stored in the form of ATP molecules. When these molecules get converted to ADP (Adenosine Diphosphate), energy is released. All the bodily functions are made possible due to ATP molecule conversion.

Hence, they are referred as energy currency of the body. To summarize, respiration at the cellular level is the collection of all metabolic processes, that breakdown carbohydrates to create Adenosine Triphosphate (ATP) molecules.


Every biological or metabolic process is very complicated and involves many reactants and products. In fact, all biological processes resemble industrial assembly lines, as every one of them is a connected chain of smaller cycles.

The formula presented here is simplified, in the sense that we only talk about what are the raw materials or reactants for the cellular respiratory process and its products. We do not go into the deep details of the process itself. Here is the formula that summarizes the whole process in short:

C6H12O6 + 6O2 --> 6CO2 + 6H2O + Energy (36 or 38 ATP molecules)

In this process, the reactants are glucose (C6H12O6) and oxygen (O2), while the products are carbon dioxide (CO2) and energy in the form of 36 or 38 ATP molecules. The small arrow in between is a substitute for a lot of complex reactions that happen at the cellular level. Still, I will summarize what happens with the main reactants in the above formula and give you the bare outlines.

There are three steps in which aerobic respiration occurs in cells. They are:
  • Glycolysis: The process of glycolysis takes place in the cytosol of the cell. Its products are 3 pyruvate molecules, 2 ATP, and 2 NADH (Nicotinamide Adenine Dinucleotide) molecules.
  • Krebs Cycle: Next is the Krebs or citric acid cycle, which occurs in the cellular mitochondria. In this process, the pyruvate molecules are acted upon and ATP molecules are released
  • Electron Transport Chain: This is the last stage of respiration, where the maximum number of ATP molecules are created.
All these metabolic processes operate through enzymes in such a way, that the energy stored within a glucose molecule is released gradually and ATP molecules are processed.

Oxidation is removal of electrons, while reduction is gaining of electrons. In the whole process of respiration, what you need to remember is that glucose gets oxidized, while oxygen gets reduced. Glucose is a high energy molecule while carbon dioxide and water molecules are comparatively low-energy molecules. Through this process, energy is released, which is used to synthesize ATP molecules. The 36 or 38 ATP molecules produced constitute about 39% of energy contained in the glucose molecule. So, we could say that the efficiency of the respiration process is 39%. Thus, the process occurs in every cell of the human body, providing energy for all the metabolic functions.