Carbohydrate catabolism
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2008-03-17T03:11:36Z
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'''Carbohydrate catabolism''' is the breakdown of carbohydrates into smaller units. The empirical formula for carbohydrates, like that of their monomer counterparts, is C<sub>X</sub>(H<sub>2Y</sub>O<sub>Y</sub>). Carbohydrates literally undergo combustion to retrieve the large amounts of energy in their bonds. Read more about [[mitochondrion|mitochondria]] to find out more about the reaction and how its energy is secured in [[Adenosine triphosphate|ATP]].
There exist different types of [[carbohydrate]]s, these are [[polysaccharide]] (e.g., [[starch]], [[amylopectin]], [[glycogen]], [[cellulose]]), [[monosaccharide]]s (e.g., [[glucose]], [[galactose]], [[fructose]], [[ribose]]) and [[disaccharide]]s (e.g., [[maltose]], [[lactose]]).
Glucose reacts with oxygen in the following [[redox]] reaction, C<sub>6</sub>H<sub>12</sub>O<sub>6</sub> + 6O<sub>2</sub> → 6CO<sub>2</sub> + 6H<sub>2</sub>O, the carbon dioxide and water is a waste product and the chemical reaction is exothermic.
The breakdown of Glucose into energy in the form of molecules of [[adenosine triphosphate|ATP]] is therefore one of the most important [[Metabolic pathway|biochemical pathways]] found in living organisms. [[Anaerobic respiration]] is the [[metabolic pathway]] where [[glucose]] is broken down in the absence of [[oxygen]]. [[Cellular respiration|Aerobic respiration]] is the pathway where glucose is broken down in the presence of [[oxygen]].
==Glycolysis==
{{Main|Glycolysis}}
The six-carbon Glucose molecule is broken down into two three-carbon [[pyruvate]] molecules yielding two [[adenosine triphosphate|ATP]] molecules and two high energy [[NADH]] molecules.
==Anaerobic respiration==
{{Main|Anaerobic respiration}}
Without [[oxidative phosphorylation]], the [[NADH]] molecules cannot be converted to ATP. When all of the NAD+ molecules have been converted to NADH, glycolysis will stop unless the NAD+ is regenerated by [[fermentation]].
==Aerobic respiration==
{{Main|Cellular respiration}}
===Pyruvate oxidation===
The three carbon [[pyruvate]] molecule loses a [[carbon]] atom and is shepherded into the [[citric acid cycle]] by [[coenzyme A]].
===The Citric acid cycle (also known as the Kreb's cycle)===
The acetyl group that came from pyruvate enters this biochemical cycle which releases [[carbon dioxide]], [[water]], and the high energy molecules [[adenosine triphosphate|ATP]], [[NADH]], and [[Flavin|FADH<sub>2</sub>]].
===Oxidative phosphorylation===
The high energy molecules [[NADH]] and [[Flavin|FADH<sub>2]] are converted into usable [[adenosine triphosphate|ATP]] molecules in the mitochondria by the mitochondrial [[electron transport chain]].
==See also==
*[[cellular respiration]]
{{Carbohydrate metabolism}}
[[Category:Metabolism]]
{{biochem-stub}}
[[ja:炭水化物異化]]
[[sr:Катаболизам угљених хидрата]]