What is anaerobic and aerobic respiration?

Aerobic respiration is a process that is occurring all the time in all cells. It involves the releasing of energy from glucose through a series of reactions using oxygen. It is the breaking down of a large glucose molecule into carbon dioxide and water, releasing energy which can be used to build larger molecules from smaller ones; for example, amino acids from nitrates.

The equation for aerobic respiration is as follows: glucose + oxygen → carbon dioxide + water (+ energy) C6H12O6 + 6O2 → 6CO2 + 6H2O

Glucose and oxygen act as inputs to the reaction and carbon dioxide and water are produced as bi-products. The site of aerobic respiration is in the mitochondria; the power house organelle of the cell.

Unlike aerobic respiration, anaerobic respiration occurs without the presence of oxygen. If oxygen is acting as a limiting factor, or demand for it is larger than the oxygen supply, muscles will anaerobically respire. This process involves the incomplete break down of glucose into lactic acid and minimal energy. The equation for anaerobic respiration is as follows:

glucose → lactic acid (+ little energy) C6H12O6 → 2C3H6O3

where lactic acid is the bi-product instead of carbon dioxide and water. Here, glucose is not fully broken down and so very minimal energy is released.

Anaerobic respiration can also occur in plants, producing ethanol and carbon dioxide instead of lactic acid. An example of this includes in the roots of plants in waterlogged soils, where very little oxygen is present.

The equation for this process is as follows; glucose → ethanol + carbon dioxide (+ energy released).