=Cellular Respiration= The food we eat contains the energy we require for all our cellular processes. However, the chemical potential energy in food must be converted to a form that is actually usable by all our cellular components. '''Cellular respiration''' is the process by which the chemical bonds of energy-rich molecules, such as glucose, are converted into a form of energy usable for life processes. This usable form of energy is known as ATP (adenosine triphosphate). '''ATP''' is a small energy carrier molecule that can be used by all the different cell organelles and is required in virtually every cellular process. [image:http://i.imgur.com/ByHRVZm.png?1] Cellular respiration occurs in the mitochondria. Cells with high energy demand such as muscle cells or motile cells such as sperm cells will have large numbers of mitochondria in order to produce sufficient cellular energy (ATP) through respiration. ==Aerobic Respiration:== Aerobic respiration is a type of respiration that ''requires oxygen''. Glucose reacts with oxygen to produce carbon dioxide and water as well as a large amount of energy (ATP) ===Glucose + Oxygen → Carbon Dioxide + Water (and lots of energy)=== ==Anaerobic Respiration:== Anaerobic respiration is a type of respiration that ''does not use oxygen''. ===Glucose → Lactic Acid (and a little energy is released)=== In mammals, during periods of intense physical activity, there may not be sufficient oxygen for aerobic respiration to meet the energy demands of the contracting muscle cells. Energy production can be supplement by breaking down Glucose into Lactic acid. While anaerobic respiration does not require oxygen it is less efficient, producing significantly less energy for each Glucose molecule. In mammals anaerobic respiration cannot be sustained for long periods of time as the build up of lactic acid would become toxic (the acidity affects proteins in our tissues). The build up of lactic acid is one of the reasons our muscles are often sore after intense exercise. The lactic acid is later be broken down into carbon dioxide and water. This type of respiration may be used when, for example, an animal is being chased by a predator. ===Glucose → Ethanol + Carbon Dioxide (and a little energy is released)=== Anaerobic respiration in plant cells and some microorganisms (such as yeast) produces ethanol and carbon dioxide, as opposed to lactic acid. Ethanol is a type of alcohol and this is why yeast is used to make beer and wine. ===Glucose → Methane + Carbon Dioxide (and a little energy is released)=== Some bacteria will produce methane (a flammable gas) as a product of anaerobic respiration.