What is Cellular respiration?
'''Cellular respiration''' is what [[cell (biology)|cells]] do to break up [[sugar]]s to get energy they can use. Cellular respiration takes in food and uses it to create [[ATP]], a [[Chemicals|chemical]] which the cell uses for energy. Usually, this process uses [[oxygen]], and is called '''aerobic respiration'''. It has four stages known as [[glycolysis]], [[Link reaction]], the [[Krebs cycle]], and the [[electron transport chain]]. This produces [[ATP]] which supplies the energy that cells need to do work. When they do not get enough oxygen, the cells use [[anaerobic respiration]], which does not use oxygen. However, this process produces [[lactic acid]], and is not as efficient as when oxygen is used. Aerobic respiration, the process that does use oxygen, produces much more energy and does not produce lactic acid. It also produces carbon dioxide as a waste product, which then enters the [[circulatory system]]. The carbon dioxide is taken to the lungs, where it is exchanged for oxygen. The simplified formula for aerobic cellular respiration is: <center>[[Glucose|C<sub>6</sub>H<sub>12</sub>O<sub>6</sub>]] + 6[[Oxygen|O<sub>2</sub>]] → 6[[Carbon dioxide|CO<SUB>2</SUB>]] + 6[[Water|H<sub>2</sub>O]] + Energy (as [[ATP]])</center> The word equation for this is:<center>[[Glucose]] (sugar) + [[Oxygen]] → [[Carbon dioxide]] + [[Water]] + Energy (as [[ATP]])</center> Aerobic cellular respiration has four stages. Each is important, and could not happen without the one before it. The steps of aerobic cellular respiration are: * [[Glycolysis]] (the break down of [[glucose]]) * [[Link reaction]] * [[Krebs cycle]] * [[Electron transport chain]], or ETC [[File:Cellularrespiration.JPG|center|border|300px]] == Glycolysis == {{main|Glycolysis}} In glycolysis, glucose in the cytoplasm is broken into two [[molecule]]s of [[pyruvate]]. Ten [[enzyme]]s are needed for the ten intermediate compounds in this process. # Two energy-rich [[ATP]] kick-start the process. # At the end are two pyruvate molecules, plus # Subst