Changes

==Etymology==

==Etymology==

International Scientific Vocabulary, from [[Greek]] metabolē  change, from metaballein to [[change]], from meta- + ballein  to throw

International Scientific Vocabulary, from [[Greek]] metabolē  change, from metaballein to [[change]], from meta- + ballein  to throw

*Date: [http://www.wikipedia.org/wiki/19th_Century 1878]

*Date: [https://www.wikipedia.org/wiki/19th_Century 1878]

==Definitions==

==Definitions==

*1 a : the sum of the [[processes]] in the buildup and destruction of [[protoplasm]]; specifically : the [[chemical]] [[changes]] in living [[cells]] by which [[energy]] is provided for [[vital]] processes and [[activities]] and new [[material]] is assimilated  

*1 a : the sum of the [[processes]] in the buildup and destruction of [[protoplasm]]; specifically : the [[chemical]] [[changes]] in living [[cells]] by which [[energy]] is provided for [[vital]] processes and [[activities]] and new [[material]] is assimilated  

:c : the sum of the metabolic [[activities]] taking place in a particular [[environment]] <the metabolism of a lake>

:c : the sum of the metabolic [[activities]] taking place in a particular [[environment]] <the metabolism of a lake>

==Description==

==Description==

'''Metabolism''' is the set of [[chemical]] [[reactions]] that happen in living [[organisms]] to [[maintain]] life. These [[processes]] allow [[organisms]] to [[grow]] and [[reproduce]], maintain their [[structures]], and [[respond]] to their [[environments]]. Metabolism is usually divided into two categories. [http://en.wikipedia.org/wiki/Catabolism Catabolism] breaks down [[organic]] [[matter]], for example to [[harvest]] [[energy]] in [[cellular]] [[respiration]]. [http://en.wikipedia.org/wiki/Anabolism Anabolism] uses [[energy]] to construct components of [[cells]] such as [http://en.wikipedia.org/wiki/Protein proteins]  and [http://en.wikipedia.org/wiki/Nucleic_acid nucleic acids].

'''Metabolism''' is the set of [[chemical]] [[reactions]] that happen in living [[organisms]] to [[maintain]] life. These [[processes]] allow [[organisms]] to [[grow]] and [[reproduce]], maintain their [[structures]], and [[respond]] to their [[environments]]. Metabolism is usually divided into two categories. [https://en.wikipedia.org/wiki/Catabolism Catabolism] breaks down [[organic]] [[matter]], for example to [[harvest]] [[energy]] in [[cellular]] [[respiration]]. [https://en.wikipedia.org/wiki/Anabolism Anabolism] uses [[energy]] to construct components of [[cells]] such as [https://en.wikipedia.org/wiki/Protein proteins]  and [https://en.wikipedia.org/wiki/Nucleic_acid nucleic acids].

The [[chemical]] [[reactions]] of metabolism are [[organized]] into metabolic pathways, in which one [[chemical]] is [[transformed]] through a [[series]] of steps into another [[chemical]], by a sequence of [http://en.wikipedia.org/wiki/Enzyme enzymes]. Enzymes are crucial to metabolism because they allow [[organisms]] to drive desirable [[reactions]] that require [[energy]] and will not occur by themselves, by coupling them to [[spontaneous]] reactions that release [[energy]]. As [http://en.wikipedia.org/wiki/Enzyme enzymes] [[act]] as [[catalysts]] they allow these [[reactions]] to proceed quickly and [[efficiently]]. Enzymes also allow the regulation of metabolic pathways in [[response]] to [[changes]] in the [[cell]]'s [[environment]] or signals from other cells.

The [[chemical]] [[reactions]] of metabolism are [[organized]] into metabolic pathways, in which one [[chemical]] is [[transformed]] through a [[series]] of steps into another [[chemical]], by a sequence of [https://en.wikipedia.org/wiki/Enzyme enzymes]. Enzymes are crucial to metabolism because they allow [[organisms]] to drive desirable [[reactions]] that require [[energy]] and will not occur by themselves, by coupling them to [[spontaneous]] reactions that release [[energy]]. As [https://en.wikipedia.org/wiki/Enzyme enzymes] [[act]] as [[catalysts]] they allow these [[reactions]] to proceed quickly and [[efficiently]]. Enzymes also allow the regulation of metabolic pathways in [[response]] to [[changes]] in the [[cell]]'s [[environment]] or signals from other cells.

The metabolism of an [[organism]] [[determines]] which substances it will find [[nutritious]] and which it will find [[poisonous]]. For example, some [http://en.wikipedia.org/wiki/Prokaryote prokaryotes] use [http://en.wikipedia.org/wiki/Hydrogen_sulfide hydrogen sulfide] as a nutrient, yet this [[gas]] is [[poisonous]] to [[animals]]. The [[speed]] of metabolism, the metabolic rate, also [[influences]] how much [[food]] an [[organism]] will require.

The metabolism of an [[organism]] [[determines]] which substances it will find [[nutritious]] and which it will find [[poisonous]]. For example, some [https://en.wikipedia.org/wiki/Prokaryote prokaryotes] use [https://en.wikipedia.org/wiki/Hydrogen_sulfide hydrogen sulfide] as a nutrient, yet this [[gas]] is [[poisonous]] to [[animals]]. The [[speed]] of metabolism, the metabolic rate, also [[influences]] how much [[food]] an [[organism]] will require.

A striking feature of metabolism is the similarity of the basic metabolic pathways and components between even vastly [[different]] [[species]]. For example, the set of [http://en.wikipedia.org/wiki/Carboxylic_acid carboxylic acids] that are best known as the [[intermediates]] in the [http://en.wikipedia.org/wiki/Citric_acid_cycle citric acid cycle] are present in all [[organisms]], being found in [[species]] as [[diverse]] as the unicellular bacteria [http://en.wikipedia.org/wiki/Escherichia_coli Escherichia coli] and huge multicellular organisms like [http://en.wikipedia.org/wiki/Elephant elephants]. These striking similarities in metabolism are probably due to the high efficiency of these pathways, and their early [[appearance]] in [[evolutionary]] [[history]].

A striking feature of metabolism is the similarity of the basic metabolic pathways and components between even vastly [[different]] [[species]]. For example, the set of [https://en.wikipedia.org/wiki/Carboxylic_acid carboxylic acids] that are best known as the [[intermediates]] in the [https://en.wikipedia.org/wiki/Citric_acid_cycle citric acid cycle] are present in all [[organisms]], being found in [[species]] as [[diverse]] as the unicellular bacteria [https://en.wikipedia.org/wiki/Escherichia_coli Escherichia coli] and huge multicellular organisms like [https://en.wikipedia.org/wiki/Elephant elephants]. These striking similarities in metabolism are probably due to the high efficiency of these pathways, and their early [[appearance]] in [[evolutionary]] [[history]].

[[Category: Chemistry]]

[[Category: Chemistry]]

[[Category: Biology]]

[[Category: Biology]]