Encyclopædia Britannica, Inc.

Cellular respiration is the procedure by which organisms use oxygen to suspension down food molecules to get chemical free energy for jail cell functions. Cellular respiration takes place in the cells of animals, plants, and fungi, and also in algae and other protists. Information technology is often called aerobic respiration because the process requires oxygen (the root aer comes from the Greek word for "air"). In the absence of oxygen, cells can get energy by breaking downwardly food through the process of fermentation, or anaerobic respiration. Of the ii processes, cellular respiration is more than efficient, yielding considerably more energy than that released through fermentation.

Cellular respiration is a chemical reaction in which glucose is broken down in the presence of oxygen, releasing chemical free energy and producing carbon dioxide and water as waste product products:

glucose + oxygen → chemical free energy + carbon dioxide + water

The energy released is captured in molecules of adenosine triphosphate, or ATP, which then supply it to fuel other cellular processes (come across biochemistry).

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All cells need energy to office. Merely as a auto must burn fuel to go the energy it needs to run, the prison cell must fire fuel—for instance, nutrient—to get energy to behave out the tasks of life. Glucose, a unproblematic sugar, provides the fuel the cell needs. Although energy is also stored in larger molecules, such every bit circuitous carbohydrates and fats, they must exist broken down into molecules of glucose earlier the cell can use their energy.

Near of cellular respiration takes identify in sausage-shaped organelles called mitochondria. Although mitochondria play a key role in other cellular processes, their principal part is to produce large amounts of energy through cellular respiration. The number of mitochondria per cell varies; liver and muscle cells, which require large amounts of energy to role, may have thousands. (Encounter also jail cell.)

Cellular respiration begins in the jail cell'south cytoplasm. At that place, glucose is cleaved down through a series of chemical reactions to produce modest molecules of a substance called pyruvate. This part of the process is called glycolysis; information technology does not require oxygen and releases a small-scale amount of free energy, which is captured by a few ATPs. The pyruvate molecules then enter the mitochondria, where they undergo a series of chemical reactions with oxygen. So much free energy is released in these reactions that it takes many molecules of ATP to capture it all. The reactions too release hydrogen, which combines with oxygen to produce h2o; and carbon, which combines with oxygen to produce carbon dioxide. The water and carbon dioxide are released as waste products; the ATPs leave the mitochondria and deliver their captured energy to places in the jail cell where it is needed to power cellular activities.