Aerobic and anaerobic respiration are both metabolic pathways of cellular respiration in plants and animals. Both biological processes break down sugars that have been previously synthesized through the process of photosynthesis into energy that can fuel cellular activity. Although they have a similar purpose, aerobic and anaerobic respiration operate and function very differently.
Presence of Oxygen
Aerobic and anaerobic cellular respiration operate in different oxygen environments. Aerobic respiration is carried out in the presence of oxygen and anaerobic respiration occurs in the absence of oxygen.
Cellular Respiration Products
Aerobic cellular respiration breaks down sugars and starches into carbon dioxide and water. Anaerobic cellular respiration, through a process referred to as fermentation, breaks down sugars and starches into lactic acid or alcohol.
Aerobic respiration is the more common type of cellular metabolism, found throughout the majority of living organisms. At the cellular level, almost all plant and animal cells require oxygen for the efficient reduction of sugar into energy molecules. Anaerobic respiration is less common, found within specific types of animal muscle cells and is the sole cellular respiration method for certain types of bacteria.
Both aerobic and anaerobic metabolic processes are designed to release energy. The type of cellular energy they produce is an energy molecule called adenosine triphosphate or ATP. Aerobic cellular respiration is far more efficient at creating ATP than anaerobic respiration, one glucose or sugar molecule yielding 38 ATPs. That same glucose molecule would yield only 2 ATPs through anaerobic respiration.
Aerobic cellular respiration produces more energy due to the presence of oxygen. In the presence of oxygen, sugar and starch molecules are able to go through the cytoplasm and into the mitochondria, in which the sugar is broken down more thoroughly and more energy is extracted through complex chemical processes.
Anaerobic respiration, on the other hand, is unable to take the sugar molecules to the mitochondria, and therefore yields energy through the cytoplasm in the chemical process known as glycolysis.