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{{short description|The set of life-sustaining chemical transformations within the cells of organisms }}

{{short description|The set of life-sustaining chemical transformations within the cells of organisms }}

[[File:Metabolism.png|thumb|细胞新陈代谢的简化图]]

[[File:Metabolism.png|thumb|细胞新陈代谢的简化图]]

[[File:ATP-3D-vdW.png|thumb|right|[[三磷酸腺苷]]的结构（ATP），它是能量代谢中的中枢中间体。]]

[[File:ATP-3D-vdW.png|thumb|right|[[三磷酸腺苷]]的结构（ATP），它是能量代谢中的中枢中间体。]]

'''Metabolism''' ({{IPAc-en|m|ə|ˈ|t|æ|b|ə|l|ɪ|z|ə|m}}, from {{lang-el|μεταβολή}} ''metabolē'', "change") is the set of [[life]]-sustaining [[chemical reactions]] in [[organisms]]. The three main purposes of metabolism are: the conversion of food to [[energy]] to run cellular processes; the conversion of food/fuel to building blocks for [[protein]]s, [[lipid]]s, [[nucleic acid]]s, and some [[carbohydrate]]s; and the elimination of [[Metabolic waste|metabolic wastes]]. These [[enzyme]]-catalyzed reactions allow organisms to grow and reproduce, maintain their structures, and respond to their environments. (The word metabolism can also refer to the sum of all chemical reactions that occur in living organisms, including [[digestion]] and the transport of substances into and between different cells, in which case the above described set of reactions within the cells is called intermediary metabolism or intermediate metabolism).

'''Metabolism''' ({{IPAc-en|m|ə|ˈ|t|æ|b|ə|l|ɪ|z|ə|m}}, from {{lang-el|μεταβολή}} ''metabolē'', "change") is the set of [[life]]-sustaining [[chemical reactions]] in [[organisms]]. The three main purposes of metabolism are: the conversion of food to [[energy]] to run cellular processes; the conversion of food/fuel to building blocks for [[protein]]s, [[lipid]]s, [[nucleic acid]]s, and some [[carbohydrate]]s; and the elimination of [[Metabolic waste|metabolic wastes]]. These [[enzyme]]-catalyzed reactions allow organisms to grow and reproduce, maintain their structures, and respond to their environments. (The word metabolism can also refer to the sum of all chemical reactions that occur in living organisms, including [[digestion]] and the transport of substances into and between different cells, in which case the above described set of reactions within the cells is called intermediary metabolism or intermediate metabolism).

== Key biochemicals ==

== 关键的生物化学成分 ==

 

{{further|Biomolecule|Cell (biology)|Biochemistry}}

{{further|Biomolecule|Cell (biology)|Biochemistry}}

构成动物、植物和微生物的大部分结构由四种基本分子组成: 氨基酸、糖类化合物、核酸和脂类(通常称为脂肪)。由于这些分子对生命至关重要，新陈代谢反应要么专注于在构建细胞和组织的过程中制造这些分子，要么将这些分子作为能量来源并将其消化分解。这些生化物质可以结合在一起形成DNA和蛋白质之类的聚合物，它们都是生命必不可少的[[大分子聚合物]]<ref>{{cite journal|last=Cooper|first=Geoffrey M.| name-list-style = vanc |date=2000|title=The Molecular Composition of Cells|url=https://www.ncbi.nlm.nih.gov/books/NBK9879/|journal=The Cell: A Molecular Approach. 2nd Edition|language=en}}</ref>。

构成动物、植物和微生物的大部分结构由四种基本分子组成: 氨基酸、糖类化合物、核酸和脂类(通常称为脂肪)。由于这些分子对生命至关重要，新陈代谢反应要么专注于在构建细胞和组织的过程中制造这些分子，要么将这些分子作为能量来源并将其消化分解。这些生化物质可以结合在一起形成DNA和蛋白质之类的聚合物，它们都是生命必不可少的[[大分子聚合物]]<ref>{{cite journal|last=Cooper|first=Geoffrey M.| name-list-style = vanc |date=2000|title=The Molecular Composition of Cells|url=https://www.ncbi.nlm.nih.gov/books/NBK9879/|journal=The Cell: A Molecular Approach. 2nd Edition|language=en}}</ref>。

<center>

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{| class=“wikitable” style = “margin-left: auto; margin-right: auto;”

{| class="wikitable “wikitable”" style="“margin-left:" auto; margin-right: auto;”

|-

|-

!分子类型 !! [[单体]]形式的名称 !! [[聚合物]]形式的名称 !! 聚合物形态的例子

!分子类型 !! [[单体]]形式的名称 !! [[聚合物]]形式的名称 !! 聚合物形态的例子

|-

|-

| 氨基酸 || [[蛋白质]](由多肽组成) || [[纤维蛋白]]和[[球状蛋白]]

| 氨基酸 || 氨基酸 ||[[蛋白质]](由多肽组成)

|[[纤维蛋白]]和[[球状蛋白]]

|-

|-

| [[碳水化合物]] || [[单糖]] || [[多糖]] || [[淀粉]], [[糖原]] and [[纤维素]]

| [[碳水化合物]] || [[单糖]] || [[多糖]] || [[淀粉]], [[糖原]] and [[纤维素]]

|-

|-

| [[核酸]] || [[核苷酸]] || [[多核苷酸]] || [[DNA]] and [[RNA]]

| [[核酸]] || [[核苷酸]] || [[多核苷酸]] || [[DNA]] and [[RNA]]<br />

|}

|}

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</center>

 

===氨基酸和蛋白质===

 

 

===Amino acids and proteins===

 

[[Protein]]s are made of [[amino acid]]s arranged in a linear chain joined together by [[peptide bond]]s. Many proteins are [[enzyme]]s that [[catalysis|catalyze]] the chemical reactions in metabolism. Other proteins have structural or mechanical functions, such as those that form the [[cytoskeleton]], a system of [[scaffolding]] that maintains the cell shape.Proteins are also important in [[cell signaling]], [[antibody|immune responses]], [[cell adhesion]], [[active transport]] across membranes, and the [[cell cycle]].Amino acids also contribute to cellular energy metabolism by providing a carbon source for entry into the citric acid cycle ([[tricarboxylic acid cycle]]), especially when a primary source of energy, such as [[glucose]], is scarce, or when cells undergo metabolic stress.

[[Protein]]s are made of [[amino acid]]s arranged in a linear chain joined together by [[peptide bond]]s. Many proteins are [[enzyme]]s that [[catalysis|catalyze]] the chemical reactions in metabolism. Other proteins have structural or mechanical functions, such as those that form the [[cytoskeleton]], a system of [[scaffolding]] that maintains the cell shape.Proteins are also important in [[cell signaling]], [[antibody|immune responses]], [[cell adhesion]], [[active transport]] across membranes, and the [[cell cycle]].Amino acids also contribute to cellular energy metabolism by providing a carbon source for entry into the citric acid cycle ([[tricarboxylic acid cycle]]), especially when a primary source of energy, such as [[glucose]], is scarce, or when cells undergo metabolic stress.

Proteins are made of amino acids arranged in a linear chain joined together by peptide bonds. Many proteins are enzymes that catalyze the chemical reactions in metabolism. Other proteins have structural or mechanical functions, such as those that form the cytoskeleton, a system of scaffolding that maintains the cell shape. Proteins are also important in cell signaling, immune responses, cell adhesion, active transport across membranes, and the cell cycle. Amino acids also contribute to cellular energy metabolism by providing a carbon source for entry into the citric acid cycle (tricarboxylic acid cycle), especially when a primary source of energy, such as glucose, is scarce, or when cells undergo metabolic stress.

Proteins are made of amino acids arranged in a linear chain joined together by peptide bonds. Many proteins are enzymes that catalyze the chemical reactions in metabolism. Other proteins have structural or mechanical functions, such as those that form the cytoskeleton, a system of scaffolding that maintains the cell shape. Proteins are also important in cell signaling, immune responses, cell adhesion, active transport across membranes, and the cell cycle. Amino acids also contribute to cellular energy metabolism by providing a carbon source for entry into the citric acid cycle (tricarboxylic acid cycle), especially when a primary source of energy, such as glucose, is scarce, or when cells undergo metabolic stress.

蛋白质是由氨基酸组成的线性链，它们通过[[肽键]]连接在一起。许多蛋白质是在新陈代谢中催化化学反应的酶。其他蛋白质具有结构或机械功能，例如那些形成[[细胞骨架]]的蛋白质（细胞骨架是维持细胞形状的支架系统）<ref>{{cite journal | vauthors = Michie KA, Löwe J | title = Dynamic filaments of the bacterial cytoskeleton | journal = Annual Review of Biochemistry | volume = 75 | issue =  | pages = 467–92 | year = 2006 | pmid = 16756499 | doi = 10.1146/annurev.biochem.75.103004.142452 | s2cid = 4550126 }}</ref> 。蛋白质在[[细胞信号传导]]、[[免疫反应]]、[[细胞粘附]]、主动跨膜转运和[[细胞周期]]中也很重要<ref name=Nelson>{{cite book | last1 = Nelson | first1 = David L. | first2 = Michael M. | last2 = Cox | name-list-style = vanc | title = Lehninger Principles of Biochemistry | publisher = W. H. Freeman and company | year = 2005 | location = New York | page = [https://archive.org/details/lehningerprincip00lehn_0/page/841 841] | isbn = 978-0-7167-4339-2 | url-access = registration | url = https://archive.org/details/lehningerprincip00lehn_0/page/841 }}</ref> 。氨基酸还通过提供碳源进入细胞三羧酸循环，促进细胞的能量代谢，<ref>{{cite journal | vauthors = Kelleher JK, Bryan BM, Mallet RT, Holleran AL, Murphy AN, Fiskum G | title = Analysis of tricarboxylic acid-cycle metabolism of hepatoma cells by comparison of 14CO2 ratios | journal = The Biochemical Journal | volume = 246 | issue = 3 | pages = 633–9 | date = September 1987 | pmid = 3120698 | pmc = 1148327 | doi = 10.1042/bj2460633 }}</ref>尤其是在[[葡萄糖]]等主要能量来源匮乏或细胞发生代谢应激时<ref>{{cite journal | vauthors = Hothersall JS, Ahmed A | title = Metabolic fate of the increased yeast amino Acid uptake subsequent to catabolite derepression | journal = Journal of Amino Acids | volume = 2013 | pages = 461901 | year = 2013 | pmid = 23431419 | pmc = 3575661 | doi = 10.1155/2013/461901 }}</ref>。

蛋白质是由氨基酸组成的线性链，它们通过[[肽键]]连接在一起。许多蛋白质是在新陈代谢中催化化学反应的酶。其他蛋白质具有结构或机械功能，例如那些形成[[细胞骨架]]的蛋白质（细胞骨架是维持细胞形状的支架系统）<ref>{{cite journal | vauthors = Michie KA, Löwe J | title = Dynamic filaments of the bacterial cytoskeleton | journal = Annual Review of Biochemistry | volume = 75 | issue =  | pages = 467–92 | year = 2006 | pmid = 16756499 | doi = 10.1146/annurev.biochem.75.103004.142452 | s2cid = 4550126 }}</ref> 。蛋白质在[[细胞信号传导]]、[[免疫反应]]、[[细胞粘附]]、主动跨膜转运和[[细胞周期]]中也很重要<ref name="Nelson">{{cite book | last1 = Nelson | first1 = David L. | first2 = Michael M. | last2 = Cox | name-list-style = vanc | title = Lehninger Principles of Biochemistry | publisher = W. H. Freeman and company | year = 2005 | location = New York | page = [https://archive.org/details/lehningerprincip00lehn_0/page/841 841] | isbn = 978-0-7167-4339-2 | url-access = registration | url = https://archive.org/details/lehningerprincip00lehn_0/page/841 }}</ref> 。氨基酸还通过提供碳源进入细胞三羧酸循环，促进细胞的能量代谢，<ref>{{cite journal | vauthors = Kelleher JK, Bryan BM, Mallet RT, Holleran AL, Murphy AN, Fiskum G | title = Analysis of tricarboxylic acid-cycle metabolism of hepatoma cells by comparison of 14CO2 ratios | journal = The Biochemical Journal | volume = 246 | issue = 3 | pages = 633–9 | date = September 1987 | pmid = 3120698 | pmc = 1148327 | doi = 10.1042/bj2460633 }}</ref>尤其是在[[葡萄糖]]等主要能量来源匮乏或细胞发生代谢应激时<ref>{{cite journal | vauthors = Hothersall JS, Ahmed A | title = Metabolic fate of the increased yeast amino Acid uptake subsequent to catabolite derepression | journal = Journal of Amino Acids | volume = 2013 | pages = 461901 | year = 2013 | pmid = 23431419 | pmc = 3575661 | doi = 10.1155/2013/461901 }}</ref>。

===Lipids===

===脂类 ===

[[Lipid]]s are the most diverse group of biochemicals. Their main structural uses are as part of [[biological membrane]]s both internal and external, such as the [[cell membrane]], or as a source of energy. Lipids are usually defined as [[hydrophobe|hydrophobic]] or [[amphiphiles|amphipathic]] biological molecules but will dissolve in [[organic solvent]]s such as [[ethanol|alcohol]], [[benzene]] or [[chloroform]]. The [[fat]]s are a large group of compounds that contain [[fatty acid]]s and [[glycerol]]; a glycerol molecule attached to three fatty acid [[ester]]s is called a [[triglyceride|triacylglyceride]]. Several variations on this basic structure exist, including backbones such as [[sphingosine]] in the [[sphingomyelin]], and [[hydrophile|hydrophilic]] groups such as [[phosphate]] as in [[phospholipid]]s. [[Steroid]]s such as [[sterol]] are another major class of lipids.

[[Lipid]]s are the most diverse group of biochemicals. Their main structural uses are as part of [[biological membrane]]s both internal and external, such as the [[cell membrane]], or as a source of energy. Lipids are usually defined as [[hydrophobe|hydrophobic]] or [[amphiphiles|amphipathic]] biological molecules but will dissolve in [[organic solvent]]s such as [[ethanol|alcohol]], [[benzene]] or [[chloroform]]. The [[fat]]s are a large group of compounds that contain [[fatty acid]]s and [[glycerol]]; a glycerol molecule attached to three fatty acid [[ester]]s is called a [[triglyceride|triacylglyceride]]. Several variations on this basic structure exist, including backbones such as [[sphingosine]] in the [[sphingomyelin]], and [[hydrophile|hydrophilic]] groups such as [[phosphate]] as in [[phospholipid]]s. [[Steroid]]s such as [[sterol]] are another major class of lipids.

===Carbohydrates===

===碳水化合物===

[[File:Glucose Fisher to Haworth.gif|thumb|upright=1.15|right|alt=The straight chain form consists of four C H O H groups linked in a row, capped at the ends by an aldehyde group C O H and a methanol group C H 2 O H.  To form the ring, the aldehyde group combines with the O H group of the next-to-last carbon at the other end, just before the methanol group.|[[Glucose]] can exist in both a straight-chain and ring form.]]

[[File:Glucose Fisher to Haworth.gif|thumb|upright=1.15|right|alt=The straight chain form consists of four C H O H groups linked in a row, capped at the ends by an aldehyde group C O H and a methanol group C H 2 O H.  To form the ring, the aldehyde group combines with the O H group of the next-to-last carbon at the other end, just before the methanol group.|葡萄糖可以以直链和环的形式存在。]]

 

 

[葡萄糖可以以直链和环的形式存在。]

[[Carbohydrate]]s are [[aldehyde]]s or [[ketone]]s, with many [[hydroxyl]] groups attached, that can exist as straight chains or rings. Carbohydrates are the most abundant biological molecules, and fill numerous roles, such as the storage and transport of [[energy]] ([[starch]], [[glycogen]]) and structural components ([[cellulose]] in plants, [[chitin]] in animals). The basic carbohydrate units are called [[monosaccharide]]s and include [[galactose]], [[fructose]], and most importantly [[glucose]]. Monosaccharides can be linked together to form [[polysaccharide]]s in almost limitless ways.

[[Carbohydrate]]s are [[aldehyde]]s or [[ketone]]s, with many [[hydroxyl]] groups attached, that can exist as straight chains or rings. Carbohydrates are the most abundant biological molecules, and fill numerous roles, such as the storage and transport of [[energy]] ([[starch]], [[glycogen]]) and structural components ([[cellulose]] in plants, [[chitin]] in animals). The basic carbohydrate units are called [[monosaccharide]]s and include [[galactose]], [[fructose]], and most importantly [[glucose]]. Monosaccharides can be linked together to form [[polysaccharide]]s in almost limitless ways.

===Nucleotides===

===核苷酸 ===

The two nucleic acids, DNA and [[RNA]], are polymers of [[nucleotide]]s. Each nucleotide is composed of a phosphate attached to a [[ribose]] or [[deoxyribose]] sugar group which is attached to a [[nitrogenous base]]. Nucleic acids are critical for the storage and use of genetic information, and its interpretation through the processes of [[transcription (genetics)|transcription]] and [[protein biosynthesis]]. This information is protected by [[DNA repair]] mechanisms and propagated through [[DNA replication]]. Many [[virus]]es have an [[RNA virus|RNA genome]], such as [[HIV]], which uses [[reverse transcription]] to create a DNA template from its viral RNA genome. RNA in [[ribozyme]]s such as [[spliceosome]]s and [[ribosome]]s is similar to enzymes as it can catalyze chemical reactions. Individual [[nucleoside]]s are made by attaching a [[nucleobase]] to a [[ribose]] sugar. These bases are [[heterocyclic]] rings cono ptaining nitrogen, classified as [[purine]]s or [[pyrimidine]]s. Nucleotides also act as coenzymes in metabolic-group-transfer reactions.

The two nucleic acids, DNA and [[RNA]], are polymers of [[nucleotide]]s. Each nucleotide is composed of a phosphate attached to a [[ribose]] or [[deoxyribose]] sugar group which is attached to a [[nitrogenous base]]. Nucleic acids are critical for the storage and use of genetic information, and its interpretation through the processes of [[transcription (genetics)|transcription]] and [[protein biosynthesis]]. This information is protected by [[DNA repair]] mechanisms and propagated through [[DNA replication]]. Many [[virus]]es have an [[RNA virus|RNA genome]], such as [[HIV]], which uses [[reverse transcription]] to create a DNA template from its viral RNA genome. RNA in [[ribozyme]]s such as [[spliceosome]]s and [[ribosome]]s is similar to enzymes as it can catalyze chemical reactions. Individual [[nucleoside]]s are made by attaching a [[nucleobase]] to a [[ribose]] sugar. These bases are [[heterocyclic]] rings cono ptaining nitrogen, classified as [[purine]]s or [[pyrimidine]]s. Nucleotides also act as coenzymes in metabolic-group-transfer reactions.

===Coenzymes===

===辅酶===

 

[[File:Acetyl-CoA-2D.svg|thumb|right|upright=1.35|[[乙酰辅酶A]]结构。可转移的[[乙酰基]]与最左边的硫原子成键结合。]]

[[File:Acetyl-CoA-2D.svg|thumb|right|upright=1.35|[[乙酰辅酶A]]结构。可转移的[[乙酰基]]与最左边的硫原子成键结合。]]

[[File:1GZX Haemoglobin.png|thumb|upright=1.35|right|The structure of iron-containing [[hemoglobin]]. 含铁[[血红蛋白]]的结构。蛋白质亚基为红色和蓝色，含铁血红素基为绿色。]]

[[File:1GZX Haemoglobin.png|thumb|upright=1.35|right|The structure of iron-containing [[hemoglobin]]. 含铁[[血红蛋白]]的结构。蛋白质亚基为红色和蓝色，含铁血红素基为绿色。]]

===Mineral and cofactors===

===矿物质和辅因子===

 

{{further||Bioinorganic chemistry}}

{{further||Bioinorganic chemistry}}

==Catabolism==

==分解代谢==

 

[[Catabolism]] is the set of metabolic processes that break down large molecules. These include breaking down and oxidizing food molecules. The purpose of the catabolic reactions is to provide the energy and components needed by anabolic reactions which build molecules. The exact nature of these catabolic reactions differ from organism to organism, and organisms can be classified based on their sources of energy and carbon (their [[primary nutritional groups]]), as shown in the table below. Organic molecules are used as a source of energy by [[organotroph]]s, while [[lithotroph]]s use inorganic substrates, and [[phototroph]]s capture sunlight as [[Potential energy#Chemical potential energy|chemical energy]].However, all these different forms of metabolism depend on [[redox]] reactions that involve the transfer of electrons from reduced donor molecules such as [[organic molecule]]s, water, [[ammonia]], [[hydrogen sulfide]] or [[Ferrous|ferrous ions]] to acceptor molecules such as [[oxygen]], [[nitrate]] or [[sulfate]]. In animals, these reactions involve complex [[organic molecule]]s that are broken down to simpler molecules, such as [[carbon dioxide]] and water. In [[photosynthesis|photosynthetic]] organisms, such as plants and [[cyanobacteria]], these electron-transfer reactions do not release energy but are used as a way of storing energy absorbed from sunlight.

[[Catabolism]] is the set of metabolic processes that break down large molecules. These include breaking down and oxidizing food molecules. The purpose of the catabolic reactions is to provide the energy and components needed by anabolic reactions which build molecules. The exact nature of these catabolic reactions differ from organism to organism, and organisms can be classified based on their sources of energy and carbon (their [[primary nutritional groups]]), as shown in the table below. Organic molecules are used as a source of energy by [[organotroph]]s, while [[lithotroph]]s use inorganic substrates, and [[phototroph]]s capture sunlight as [[Potential energy#Chemical potential energy|chemical energy]].However, all these different forms of metabolism depend on [[redox]] reactions that involve the transfer of electrons from reduced donor molecules such as [[organic molecule]]s, water, [[ammonia]], [[hydrogen sulfide]] or [[Ferrous|ferrous ions]] to acceptor molecules such as [[oxygen]], [[nitrate]] or [[sulfate]]. In animals, these reactions involve complex [[organic molecule]]s that are broken down to simpler molecules, such as [[carbon dioxide]] and water. In [[photosynthesis|photosynthetic]] organisms, such as plants and [[cyanobacteria]], these electron-transfer reactions do not release energy but are used as a way of storing energy absorbed from sunlight.

分解代谢是指分解大分子的一系列代谢过程。其中包括分解和氧化食物分子。分解代谢反应的目的是为构建分子的合成代谢反应提供所需的能量和成分。这些分解代谢反应的确切性质因生物体而异<ref name="Alberts 2002">{{cite book |last1=Alberts|first1=Bruce|last2=Johnson|first2=Alexander|last3=Lewis|first3=Julian|last4=Raff|first4=Martin|last5=Roberts|first5=Keith|last6=Walter|first6=Peter| name-list-style = vanc |date=2002|chapter =How Cells Obtain Energy from Food|url=https://www.ncbi.nlm.nih.gov/books/NBK26882/|title =Molecular Biology of the Cell | edition = 4th |language=en|via=NCBI}}</ref>，生物体可以根据它们的能量和碳的来源（其主要营养组）进行分类，如下表所示。有机养生物把有机分子作为能量来源，而岩养生物利用无机基质，光养生物利用阳光（获得化学能）<ref>{{cite journal|last=Raven|first=Ja| name-list-style = vanc |date=2009-09-03|title=Contributions of anoxygenic and oxygenic phototrophy and chemolithotrophy to carbon and oxygen fluxes in aquatic environments|url=http://www.int-res.com/abstracts/ame/v56/n2-3/p177-192/|journal=Aquatic Microbial Ecology|language=en|volume=56|pages=177–192|doi=10.3354/ame01315|issn=0948-3055|doi-access=free}}</ref> 。然而，所有这些不同形式的新陈代谢都依赖于氧化还原反应，这些反应涉及电子从还原的供体分子（如有机分子，水，氨，硫化氢或亚铁离子）转移到受体分子（如氧，硝酸盐或硫酸盐）。在动物中，这些反应涉及复杂的有机分子，它们被分解成更简单的分子，如二氧化碳和水。在诸如植物和蓝藻这样的光合生物体中，这些电子转移反应不释放能量，而是用来储存从阳光中吸收的能量<ref name=Nelson2004>{{cite journal | vauthors = Nelson N, Ben-Shem A | title = The complex architecture of oxygenic photosynthesis | journal = Nature Reviews. Molecular Cell Biology | volume = 5 | issue = 12 | pages = 971–82 | date = December 2004 | pmid = 15573135 | doi = 10.1038/nrm1525 | s2cid = 5686066 }}</ref>。

分解代谢是指分解大分子的一系列代谢过程。其中包括分解和氧化食物分子。分解代谢反应的目的是为构建分子的合成代谢反应提供所需的能量和成分。这些分解代谢反应的确切性质因生物体而异<ref name="Alberts 2002">{{cite book |last1=Alberts|first1=Bruce|last2=Johnson|first2=Alexander|last3=Lewis|first3=Julian|last4=Raff|first4=Martin|last5=Roberts|first5=Keith|last6=Walter|first6=Peter| name-list-style = vanc |date=2002|chapter =How Cells Obtain Energy from Food|url=https://www.ncbi.nlm.nih.gov/books/NBK26882/|title =Molecular Biology of the Cell | edition = 4th |language=en|via=NCBI}}</ref>，生物体可以根据它们的能量和碳的来源（其主要营养组）进行分类，如下表所示。有机养生物把有机分子作为能量来源，而岩养生物利用无机基质，光养生物利用阳光（获得化学能）<ref>{{cite journal|last=Raven|first=Ja| name-list-style = vanc |date=2009-09-03|title=Contributions of anoxygenic and oxygenic phototrophy and chemolithotrophy to carbon and oxygen fluxes in aquatic environments|url=http://www.int-res.com/abstracts/ame/v56/n2-3/p177-192/|journal=Aquatic Microbial Ecology|language=en|volume=56|pages=177–192|doi=10.3354/ame01315|issn=0948-3055|doi-access=free}}</ref> 。然而，所有这些不同形式的新陈代谢都依赖于氧化还原反应，这些反应涉及电子从还原的供体分子（如有机分子，水，氨，硫化氢或亚铁离子）转移到受体分子（如氧，硝酸盐或硫酸盐）。在动物中，这些反应涉及复杂的有机分子，它们被分解成更简单的分子，如二氧化碳和水。在诸如植物和蓝藻这样的光合生物体中，这些电子转移反应不释放能量，而是用来储存从阳光中吸收的能量<ref name=Nelson2004>{{cite journal | vauthors = Nelson N, Ben-Shem A | title = The complex architecture of oxygenic photosynthesis | journal = Nature Reviews. Molecular Cell Biology | volume = 5 | issue = 12 | pages = 971–82 | date = December 2004 | pmid = 15573135 | doi = 10.1038/nrm1525 | s2cid = 5686066 }}</ref>。

 

{|

 

 

! rowspan="2" |能量

{| class="wikitable float-right"  style="text-align:center; width:50%;"

 

!photo-

{| class="wikitable float-right"  style="text-align:center; width:50%;"

 

{ | class = “ wikitable float-right” style = “ text-align: center; width: 50% ; ”

! rowspan="6" |-troph

 

|+Classification of organisms based on their metabolism <ref>{{cite book| vauthors = Madigan MT, Martinko JM |title=Brock Mikrobiologie|date=2006|publisher=Pearson Studium|isbn=3-8273-7187-2|edition=11., überarb. Aufl|location=München|pages=604, 621|oclc=162303067}}</ref>

 

 

 

|-

|-

 

|-

|-

 

| rowspan="2" |电子供体

|有机化合物

 

|

| rowspan="2" style="background:#ff0;"|Energy source || style="background:#ff0;"| sunlight || style="background:#ff0;"| photo- || rowspan=2 colspan=2 | &nbsp; || rowspan="6" style="background:#7fc31c;"| -troph

|organo-

 

|

| rowspan="2" style="background:#ff0;"|Energy source || style="background:#ff0;"| sunlight || style="background:#ff0;"| photo- || rowspan=2 colspan=2 | &nbsp; || rowspan="6" style="background:#7fc31c;"| -troph

 

|- style="background:#ff0;"

 

 

 

 

 

 

 

 

 

 

 

有机化合物 | rowspan = 2 | | | style = ”背景: # ffb300; ” | organic compound = 2 | | | style = ”背景: # ffb300; ” | organo-| rowspan = 2 |

 

 

|- style="background:#ffb300;"

 

 

 

 

 

|-

|-

 

|-

|-

 

|-

|-

 

|无机化合物

| rowspan="2" style="background:#fb805f;"| Carbon source || style="background:#fb805f;"| [[organic compound]] || rowspan=2 colspan=2 | &nbsp; || style="background:#fb805f;"| hetero-

|

 

|

|auto-

 

|- style="background:#fb805f;"

 

 

 

|| [[inorganic compound]] || style="background:#fb805f;"| auto-

 

|| inorganic compound || style="background:#fb805f;"| auto-

 

 

 

 

|}

|}

===Digestion===

===消化===

 

{{further|Digestion|Gastrointestinal tract}}

{{further|Digestion|Gastrointestinal tract}}

===Energy from organic compounds===

===有机化合物的能量===

 

{{further|Cellular respiration|Fermentation (biochemistry)|Carbohydrate catabolism|Fat catabolism|Protein catabolism}}

{{further|Cellular respiration|Fermentation (biochemistry)|Carbohydrate catabolism|Fat catabolism|Protein catabolism}}

Carbohydrate catabolism is the breakdown of carbohydrates into smaller units. Carbohydrates are usually taken into cells once they have been digested into monosaccharides. Once inside, the major route of breakdown is glycolysis, where sugars such as glucose and fructose are converted into pyruvate and some ATP is generated. Pyruvate is an intermediate in several metabolic pathways, but the majority is converted to acetyl-CoA through aerobic (with oxygen) glycolysis and fed into the citric acid cycle. Although some more ATP is generated in the citric acid cycle, the most important product is NADH, which is made from NAD⁺ as the acetyl-CoA is oxidized. This oxidation releases carbon dioxide as a waste product. In anaerobic conditions, glycolysis produces lactate, through the enzyme lactate dehydrogenase re-oxidizing NADH to NAD+ for re-use in glycolysis. An alternative route for glucose breakdown is the pentose phosphate pathway, which reduces the coenzyme NADPH and produces pentose sugars such as ribose, the sugar component of nucleic acids.

Carbohydrate catabolism is the breakdown of carbohydrates into smaller units. Carbohydrates are usually taken into cells once they have been digested into monosaccharides. Once inside, the major route of breakdown is glycolysis, where sugars such as glucose and fructose are converted into pyruvate and some ATP is generated. Pyruvate is an intermediate in several metabolic pathways, but the majority is converted to acetyl-CoA through aerobic (with oxygen) glycolysis and fed into the citric acid cycle. Although some more ATP is generated in the citric acid cycle, the most important product is NADH, which is made from NAD⁺ as the acetyl-CoA is oxidized. This oxidation releases carbon dioxide as a waste product. In anaerobic conditions, glycolysis produces lactate, through the enzyme lactate dehydrogenase re-oxidizing NADH to NAD+ for re-use in glycolysis. An alternative route for glucose breakdown is the pentose phosphate pathway, which reduces the coenzyme NADPH and produces pentose sugars such as ribose, the sugar component of nucleic acids.

碳水化合物分解代谢是将碳水化合物分解成较小的单位的过程。碳水化合物一旦被消化成单糖，通常就被带入细胞。一旦进入细胞内<ref>{{cite journal | vauthors = Bell GI, Burant CF, Takeda J, Gould GW | title = Structure and function of mammalian facilitative sugar transporters | journal = The Journal of Biological Chemistry | volume = 268 | issue = 26 | pages = 19161–4 | date = September 1993 | pmid = 8366068 }}</ref>，分解的主要途径就是糖酵解，其中糖（例如葡萄糖和果糖）被转化为丙酮酸并生成一些ATP。<ref name=Bouche>{{cite journal | vauthors = Bouché C, Serdy S, Kahn CR, Goldfine AB | title = The cellular fate of glucose and its relevance in type 2 diabetes | journal = Endocrine Reviews | volume = 25 | issue = 5 | pages = 807–30 | date = October 2004 | pmid = 15466941 | doi = 10.1210/er.2003-0026 | df = dmy-all | doi-access = free }}</ref>丙酮酸是几种代谢途径中的中间体，但大多数通过有氧（含氧）糖酵解转化为乙酰辅酶A并进入三羧酸循环。尽管在三羧酸循环中会产生更多的ATP，但最重要的产物是NADH，它是由 NAD < sup > + </sup > 在乙酰辅酶A被氧化后制成的。这种氧化释放出作为废物的二氧化碳。在厌氧条件下，糖酵解产生乳酸盐，即由乳酸脱氢酶将丙酮酸盐转化为乳酸盐，同时将NADH重新氧化为NAD < sup > + </sup > 再用于糖酵解。<ref>{{cite journal | vauthors = Alfarouk KO, Verduzco D, Rauch C, Muddathir AK, Adil HH, Elhassan GO, Ibrahim ME, David Polo Orozco J, Cardone RA, Reshkin SJ, Harguindey S | display-authors = 6 | title = Glycolysis, tumor metabolism, cancer growth and dissemination. A new pH-based etiopathogenic perspective and therapeutic approach to an old cancer question | journal = Oncoscience | volume = 1 | issue = 12 | pages = 777–802 | date = 18 December 2014 | pmid = 25621294 | pmc = 4303887 | doi = 10.18632/oncoscience.109 | doi-access = free }}</ref>葡萄糖分解的另一种途径是磷酸戊糖途径，它还原辅酶NADPH并产生戊糖，如核糖（核酸的糖成分）。

碳水化合物分解代谢是将碳水化合物分解成较小的单位的过程。碳水化合物一旦被消化成单糖，通常就被带入细胞。一旦进入细胞内<ref>{{cite journal | vauthors = Bell GI, Burant CF, Takeda J, Gould GW | title = Structure and function of mammalian facilitative sugar transporters | journal = The Journal of Biological Chemistry | volume = 268 | issue = 26 | pages = 19161–4 | date = September 1993 | pmid = 8366068 }}</ref>，分解的主要途径就是糖酵解，其中糖（例如葡萄糖和果糖）被转化为丙酮酸并生成一些ATP。<ref name=Bouche>{{cite journal | vauthors = Bouché C, Serdy S, Kahn CR, Goldfine AB | title = The cellular fate of glucose and its relevance in type 2 diabetes | journal = Endocrine Reviews | volume = 25 | issue = 5 | pages = 807–30 | date = October 2004 | pmid = 15466941 | doi = 10.1210/er.2003-0026 | df = dmy-all | doi-access = free }}</ref>丙酮酸是几种代谢途径中的中间体，但大多数通过有氧（含氧）糖酵解转化为乙酰辅酶A并进入三羧酸循环。尽管在三羧酸循环中会产生更多的ATP，但最重要的产物是NADH，它是由 NAD < sup > + 在乙酰辅酶A被氧化后制成的。这种氧化释放出作为废物的二氧化碳。在厌氧条件下，糖酵解产生乳酸盐，即由乳酸脱氢酶将丙酮酸盐转化为乳酸盐，同时将NADH重新氧化为NAD < sup > + 再用于糖酵解。<ref>{{cite journal | vauthors = Alfarouk KO, Verduzco D, Rauch C, Muddathir AK, Adil HH, Elhassan GO, Ibrahim ME, David Polo Orozco J, Cardone RA, Reshkin SJ, Harguindey S | display-authors = 6 | title = Glycolysis, tumor metabolism, cancer growth and dissemination. A new pH-based etiopathogenic perspective and therapeutic approach to an old cancer question | journal = Oncoscience | volume = 1 | issue = 12 | pages = 777–802 | date = 18 December 2014 | pmid = 25621294 | pmc = 4303887 | doi = 10.18632/oncoscience.109 | doi-access = free }}</ref>葡萄糖分解的另一种途径是磷酸戊糖途径，它还原辅酶NADPH并产生戊糖，如核糖（核酸的糖成分）。

Fats are catabolised by [[hydrolysis]] to free fatty acids and glycerol. The glycerol enters glycolysis and the fatty acids are broken down by [[beta oxidation]] to release acetyl-CoA, which then is fed into the citric acid cycle. Fatty acids release more energy upon oxidation than carbohydrates because carbohydrates contain more oxygen in their structures. Steroids are also broken down by some bacteria in a process similar to beta oxidation, and this breakdown process involves the release of significant amounts of acetyl-CoA, propionyl-CoA, and pyruvate, which can all be used by the cell for energy. ''M. tuberculosis'' can also grow on the lipid [[cholesterol]] as a sole source of carbon, and genes involved in the cholesterol use pathway(s) have been validated as important during various stages of the infection lifecycle of ''M. tuberculosis''.

Fats are catabolised by [[hydrolysis]] to free fatty acids and glycerol. The glycerol enters glycolysis and the fatty acids are broken down by [[beta oxidation]] to release acetyl-CoA, which then is fed into the citric acid cycle. Fatty acids release more energy upon oxidation than carbohydrates because carbohydrates contain more oxygen in their structures. Steroids are also broken down by some bacteria in a process similar to beta oxidation, and this breakdown process involves the release of significant amounts of acetyl-CoA, propionyl-CoA, and pyruvate, which can all be used by the cell for energy. ''M. tuberculosis'' can also grow on the lipid [[cholesterol]] as a sole source of carbon, and genes involved in the cholesterol use pathway(s) have been validated as important during various stages of the infection lifecycle of ''M. tuberculosis''.

氨基酸可以用来合成蛋白质和其他生物分子，也可以被氧化成尿素和二氧化碳从而提供能量<ref>{{cite journal | vauthors = Sakami W, Harrington H | title = Amino Acid Metabolism | journal = Annual Review of Biochemistry | volume = 32 | issue =  | pages = 355–98 | year = 1963 | pmid = 14144484 | doi = 10.1146/annurev.bi.32.070163.002035 }}</ref>。氧化途径从转氨酶去除氨基酸上的氨基开始。氨基进入尿素循环，留下酮酸形式的脱氨基碳骨架。其中一些酮酸是三羧酸循环的中间产物，例如谷氨酸的脱氨反应形成 α- 酮戊二酸<ref>{{cite journal | vauthors = Brosnan JT | title = Glutamate, at the interface between amino acid and carbohydrate metabolism | journal = The Journal of Nutrition | volume = 130 | issue = 4S Suppl | pages = 988S–90S | date = April 2000 | pmid = 10736367 | doi = 10.1093/jn/130.4.988S | doi-access = free }}</ref>。葡萄糖原氨基酸也可以通过糖异生作用转化为葡萄糖(具体内容见下文)<ref>{{cite journal | vauthors = Young VR, Ajami AM | title = Glutamine: the emperor or his clothes? | journal = The Journal of Nutrition | volume = 131 | issue = 9 Suppl | pages = 2449S–59S; discussion 2486S–7S | date = September 2001 | pmid = 11533293 | doi = 10.1093/jn/131.9.2449S | doi-access = free }}</ref>。

氨基酸可以用来合成蛋白质和其他生物分子，也可以被氧化成尿素和二氧化碳从而提供能量<ref>{{cite journal | vauthors = Sakami W, Harrington H | title = Amino Acid Metabolism | journal = Annual Review of Biochemistry | volume = 32 | issue =  | pages = 355–98 | year = 1963 | pmid = 14144484 | doi = 10.1146/annurev.bi.32.070163.002035 }}</ref>。氧化途径从转氨酶去除氨基酸上的氨基开始。氨基进入尿素循环，留下酮酸形式的脱氨基碳骨架。其中一些酮酸是三羧酸循环的中间产物，例如谷氨酸的脱氨反应形成 α- 酮戊二酸<ref>{{cite journal | vauthors = Brosnan JT | title = Glutamate, at the interface between amino acid and carbohydrate metabolism | journal = The Journal of Nutrition | volume = 130 | issue = 4S Suppl | pages = 988S–90S | date = April 2000 | pmid = 10736367 | doi = 10.1093/jn/130.4.988S | doi-access = free }}</ref>。葡萄糖原氨基酸也可以通过糖异生作用转化为葡萄糖(具体内容见下文)<ref>{{cite journal | vauthors = Young VR, Ajami AM | title = Glutamine: the emperor or his clothes? | journal = The Journal of Nutrition | volume = 131 | issue = 9 Suppl | pages = 2449S–59S; discussion 2486S–7S | date = September 2001 | pmid = 11533293 | doi = 10.1093/jn/131.9.2449S | doi-access = free }}</ref>。

 

==能量转换==

 

===氧化磷酸化===

 

==Energy transformations==

 

===Oxidative phosphorylation===

 

{{further|Oxidative phosphorylation|Chemiosmosis|Mitochondrion}}

{{further|Oxidative phosphorylation|Chemiosmosis|Mitochondrion}}

将质子泵出线粒体，会在膜上形成质子浓度差，产生电化学梯度。<ref>{{cite journal | vauthors = Capaldi RA, Aggeler R | title = Mechanism of the F(1)F(0)-type ATP synthase, a biological rotary motor | journal = Trends in Biochemical Sciences | volume = 27 | issue = 3 | pages = 154–60 | date = March 2002 | pmid = 11893513 | doi = 10.1016/S0968-0004(01)02051-5 }}</ref>这种力量促使质子通过ATP合成酶的基座回到线粒体中。质子的流动使柄亚基旋转，从而改变合成酶域的活性位点的形状，使二磷酸腺苷磷酸化--变成ATP<ref name=Dimroth/>。

将质子泵出线粒体，会在膜上形成质子浓度差，产生电化学梯度。<ref>{{cite journal | vauthors = Capaldi RA, Aggeler R | title = Mechanism of the F(1)F(0)-type ATP synthase, a biological rotary motor | journal = Trends in Biochemical Sciences | volume = 27 | issue = 3 | pages = 154–60 | date = March 2002 | pmid = 11893513 | doi = 10.1016/S0968-0004(01)02051-5 }}</ref>这种力量促使质子通过ATP合成酶的基座回到线粒体中。质子的流动使柄亚基旋转，从而改变合成酶域的活性位点的形状，使二磷酸腺苷磷酸化--变成ATP<ref name=Dimroth/>。

===Energy from inorganic compounds===

===无机化合物的能量===

 

{{further|Microbial metabolism|Nitrogen cycle}}

{{further|Microbial metabolism|Nitrogen cycle}}

化能无机营养是在原核生物中发现的一种新陈代谢，其能量来自于无机化合物的氧化。这些生物可以利用氢气、<ref>{{cite journal | vauthors = Friedrich B, Schwartz E | title = Molecular biology of hydrogen utilization in aerobic chemolithotrophs | journal = Annual Review of Microbiology | volume = 47 | issue =  | pages = 351–83 | year = 1993 | pmid = 8257102 | doi = 10.1146/annurev.mi.47.100193.002031 }}</ref> 还原硫化合物(如硫化物、硫化氢和硫代硫酸酯<ref>{{cite journal | vauthors = Weber KA, Achenbach LA, Coates JD | title = Microorganisms pumping iron: anaerobic microbial iron oxidation and reduction | journal = Nature Reviews. Microbiology | volume = 4 | issue = 10 | pages = 752–64 | date = October 2006 | pmid = 16980937 | doi = 10.1038/nrmicro1490 | url = https://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=1203&context=bioscifacpub | s2cid = 8528196 }}</ref>)或氨<ref>{{cite journal | vauthors = Jetten MS, Strous M, van de Pas-Schoonen KT, Schalk J, van Dongen UG, van de Graaf AA, Logemann S, Muyzer G, van Loosdrecht MC, Kuenen JG | display-authors = 6 | title = The anaerobic oxidation of ammonium | journal = FEMS Microbiology Reviews | volume = 22 | issue = 5 | pages = 421–37 | date = December 1998 | pmid = 9990725 | doi = 10.1111/j.1574-6976.1998.tb00379.x | doi-access = free }}</ref>作为还原力的来源，它们从这些化合物与氧或亚硝酸盐等电子接受体的氧化作用中获得能量。这些微生物过程<ref>{{cite journal | vauthors = Simon J | title = Enzymology and bioenergetics of respiratory nitrite ammonification | journal = FEMS Microbiology Reviews | volume = 26 | issue = 3 | pages = 285–309 | date = August 2002 | pmid = 12165429 | doi = 10.1111/j.1574-6976.2002.tb00616.x | doi-access = free }}</ref>在全球生物地球化学循环（如乙酰化、硝化和反硝化）中非常重要，对土壤肥力也很关键<ref>{{cite journal | vauthors = Conrad R | title = Soil microorganisms as controllers of atmospheric trace gases (H2, CO, CH4, OCS, N2O, and NO) | journal = Microbiological Reviews | volume = 60 | issue = 4 | pages = 609–40 | date = December 1996 | pmid = 8987358 | pmc = 239458 | doi = 10.1128/MMBR.60.4.609-640.1996 }}</ref><ref>{{cite journal | vauthors = Barea JM, Pozo MJ, Azcón R, Azcón-Aguilar C | title = Microbial co-operation in the rhizosphere | journal = Journal of Experimental Botany | volume = 56 | issue = 417 | pages = 1761–78 | date = July 2005 | pmid = 15911555 | doi = 10.1093/jxb/eri197 | doi-access = free }}</ref>。

化能无机营养是在原核生物中发现的一种新陈代谢，其能量来自于无机化合物的氧化。这些生物可以利用氢气、<ref>{{cite journal | vauthors = Friedrich B, Schwartz E | title = Molecular biology of hydrogen utilization in aerobic chemolithotrophs | journal = Annual Review of Microbiology | volume = 47 | issue =  | pages = 351–83 | year = 1993 | pmid = 8257102 | doi = 10.1146/annurev.mi.47.100193.002031 }}</ref> 还原硫化合物(如硫化物、硫化氢和硫代硫酸酯<ref>{{cite journal | vauthors = Weber KA, Achenbach LA, Coates JD | title = Microorganisms pumping iron: anaerobic microbial iron oxidation and reduction | journal = Nature Reviews. Microbiology | volume = 4 | issue = 10 | pages = 752–64 | date = October 2006 | pmid = 16980937 | doi = 10.1038/nrmicro1490 | url = https://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=1203&context=bioscifacpub | s2cid = 8528196 }}</ref>)或氨<ref>{{cite journal | vauthors = Jetten MS, Strous M, van de Pas-Schoonen KT, Schalk J, van Dongen UG, van de Graaf AA, Logemann S, Muyzer G, van Loosdrecht MC, Kuenen JG | display-authors = 6 | title = The anaerobic oxidation of ammonium | journal = FEMS Microbiology Reviews | volume = 22 | issue = 5 | pages = 421–37 | date = December 1998 | pmid = 9990725 | doi = 10.1111/j.1574-6976.1998.tb00379.x | doi-access = free }}</ref>作为还原力的来源，它们从这些化合物与氧或亚硝酸盐等电子接受体的氧化作用中获得能量。这些微生物过程<ref>{{cite journal | vauthors = Simon J | title = Enzymology and bioenergetics of respiratory nitrite ammonification | journal = FEMS Microbiology Reviews | volume = 26 | issue = 3 | pages = 285–309 | date = August 2002 | pmid = 12165429 | doi = 10.1111/j.1574-6976.2002.tb00616.x | doi-access = free }}</ref>在全球生物地球化学循环（如乙酰化、硝化和反硝化）中非常重要，对土壤肥力也很关键<ref>{{cite journal | vauthors = Conrad R | title = Soil microorganisms as controllers of atmospheric trace gases (H2, CO, CH4, OCS, N2O, and NO) | journal = Microbiological Reviews | volume = 60 | issue = 4 | pages = 609–40 | date = December 1996 | pmid = 8987358 | pmc = 239458 | doi = 10.1128/MMBR.60.4.609-640.1996 }}</ref><ref>{{cite journal | vauthors = Barea JM, Pozo MJ, Azcón R, Azcón-Aguilar C | title = Microbial co-operation in the rhizosphere | journal = Journal of Experimental Botany | volume = 56 | issue = 417 | pages = 1761–78 | date = July 2005 | pmid = 15911555 | doi = 10.1093/jxb/eri197 | doi-access = free }}</ref>。

===Energy from light===

===光能 ===

{{further|Phototroph|Photophosphorylation|Chloroplast}}

{{further|Phototroph|Photophosphorylation|Chloroplast}}

In plants, algae, and cyanobacteria, [[photosystem|photosystem II]] uses light energy to remove electrons from water, releasing oxygen as a waste product. The electrons then flow to the [[cytochrome b6f complex]], which uses their energy to pump protons across the [[thylakoid]] membrane in the [[chloroplast]]. These protons move back through the membrane as they drive the ATP synthase, as before. The electrons then flow through [[photosystem|photosystem I]] and can then either be used to reduce the coenzyme NADP^+.f. These cooenzyme can be used in the [[Calvin cycle]], which is discussed below, or recycled for further ATP generation.

In plants, algae, and cyanobacteria, [[photosystem|photosystem II]] uses light energy to remove electrons from water, releasing oxygen as a waste product. The electrons then flow to the [[cytochrome b6f complex]], which uses their energy to pump protons across the [[thylakoid]] membrane in the [[chloroplast]]. These protons move back through the membrane as they drive the ATP synthase, as before. The electrons then flow through [[photosystem|photosystem I]] and can then either be used to reduce the coenzyme NADP^+.f. These cooenzyme can be used in the [[Calvin cycle]], which is discussed below, or recycled for further ATP generation.

In plants, algae, and cyanobacteria, photosystem II uses light energy to remove electrons from water, releasing oxygen as a waste product. The electrons then flow to the cytochrome b6f complex, which uses their energy to pump protons across the thylakoid membrane in the chloroplast. These protons move back through the membrane as they drive the ATP synthase, as before. The electrons then flow through photosystem I and can then either be used to reduce the coenzyme NADP< sup > + </sup > .fThese cooenzyme can be used in the Calvin cycle, which is discussed below, or recycled for further ATP generation.

In plants, algae, and cyanobacteria, photosystem II uses light energy to remove electrons from water, releasing oxygen as a waste product. The electrons then flow to the cytochrome b6f complex, which uses their energy to pump protons across the thylakoid membrane in the chloroplast. These protons move back through the membrane as they drive the ATP synthase, as before. The electrons then flow through photosystem I and can then either be used to reduce the coenzyme NADP< sup > + .fThese cooenzyme can be used in the Calvin cycle, which is discussed below, or recycled for further ATP generation.

在植物、藻类和蓝藻中，光系统 II 利用光能将电子从水中移走，释放出氧气。然后电子流向细胞色素b6f蛋白复合体，后者利用它们的能量穿过叶绿体中的类囊体膜，泵入质子<ref name=Nelson2004/>。这些质子在驱动ATP合成酶时通过膜向后移动，就像之前一样。然后电子流经光系统I，可以用来减少辅酶NADP< sup > + </sup ><ref>{{cite journal | vauthors = Munekage Y, Hashimoto M, Miyake C, Tomizawa K, Endo T, Tasaka M, Shikanai T | title = Cyclic electron flow around photosystem I is essential for photosynthesis | journal = Nature | volume = 429 | issue = 6991 | pages = 579–82 | date = June 2004 | pmid = 15175756 | doi = 10.1038/nature02598 | bibcode = 2004Natur.429..579M | s2cid = 4421776 }}</ref>。这些辅酶可用于[[卡尔文循环]](下文将对此进行讨论)，或被循环用于进一步生成ATP。

在植物、藻类和蓝藻中，光系统 II 利用光能将电子从水中移走，释放出氧气。然后电子流向细胞色素b6f蛋白复合体，后者利用它们的能量穿过叶绿体中的类囊体膜，泵入质子<ref name=Nelson2004/>。这些质子在驱动ATP合成酶时通过膜向后移动，就像之前一样。然后电子流经光系统I，可以用来减少辅酶NADP< sup > + </sup ><ref>{{cite journal | vauthors = Munekage Y, Hashimoto M, Miyake C, Tomizawa K, Endo T, Tasaka M, Shikanai T | title = Cyclic electron flow around photosystem I is essential for photosynthesis | journal = Nature | volume = 429 | issue = 6991 | pages = 579–82 | date = June 2004 | pmid = 15175756 | doi = 10.1038/nature02598 | bibcode = 2004Natur.429..579M | s2cid = 4421776 }}</ref>。这些辅酶可用于[[卡尔文循环]](下文将对此进行讨论)，或被循环用于进一步生成ATP。

==Anabolism==

==合成代谢==

 

{{further|Anabolism}}

{{further|Anabolism}}

。

。

===Carbon fixation===

===碳固定 ===

{{further|Photosynthesis|Carbon fixation|Chemosynthesis}}

{{further|Photosynthesis|Carbon fixation|Chemosynthesis}}

在能够光合作用的原核生物中，碳固定的机制更加多样。对它们而言，二氧化碳可以通过Calvin– Benson循环、反向三羧酸循环<ref>{{cite journal | vauthors = Hügler M, Wirsen CO, Fuchs G, Taylor CD, Sievert SM | title = Evidence for autotrophic CO2 fixation via the reductive tricarboxylic acid cycle by members of the epsilon subdivision of proteobacteria | journal = Journal of Bacteriology | volume = 187 | issue = 9 | pages = 3020–7 | date = May 2005 | pmid = 15838028 | pmc = 1082812 | doi = 10.1128/JB.187.9.3020-3027.2005 }}</ref>或乙酰辅酶A的羧化作用得到固定。原核化能自养生物也通过Calvin– Benson环固定CO < sub > 2 </sub ><ref>{{cite journal | vauthors = Strauss G, Fuchs G | title = Enzymes of a novel autotrophic CO2 fixation pathway in the phototrophic bacterium Chloroflexus aurantiacus, the 3-hydroxypropionate cycle | journal = European Journal of Biochemistry | volume = 215 | issue = 3 | pages = 633–43 | date = August 1993 | pmid = 8354269 | doi = 10.1111/j.1432-1033.1993.tb18074.x }}</ref><ref>{{cite journal | vauthors = Wood HG | title = Life with CO or CO2 and H2 as a source of carbon and energy | journal = FASEB Journal | volume = 5 | issue = 2 | pages = 156–63 | date = February 1991 | pmid = 1900793 | doi = 10.1096/fasebj.5.2.1900793 | s2cid = 45967404 }}</ref>，但它们利用无机化合物的能量来驱动反应<ref>{{cite journal | vauthors = Shively JM, van Keulen G, Meijer WG | title = Something from almost nothing: carbon dioxide fixation in chemoautotrophs | journal = Annual Review of Microbiology | volume = 52 | issue =  | pages = 191–230 | year = 1998 | pmid = 9891798 | doi = 10.1146/annurev.micro.52.1.191 }}</ref>。

在能够光合作用的原核生物中，碳固定的机制更加多样。对它们而言，二氧化碳可以通过Calvin– Benson循环、反向三羧酸循环<ref>{{cite journal | vauthors = Hügler M, Wirsen CO, Fuchs G, Taylor CD, Sievert SM | title = Evidence for autotrophic CO2 fixation via the reductive tricarboxylic acid cycle by members of the epsilon subdivision of proteobacteria | journal = Journal of Bacteriology | volume = 187 | issue = 9 | pages = 3020–7 | date = May 2005 | pmid = 15838028 | pmc = 1082812 | doi = 10.1128/JB.187.9.3020-3027.2005 }}</ref>或乙酰辅酶A的羧化作用得到固定。原核化能自养生物也通过Calvin– Benson环固定CO < sub > 2 </sub ><ref>{{cite journal | vauthors = Strauss G, Fuchs G | title = Enzymes of a novel autotrophic CO2 fixation pathway in the phototrophic bacterium Chloroflexus aurantiacus, the 3-hydroxypropionate cycle | journal = European Journal of Biochemistry | volume = 215 | issue = 3 | pages = 633–43 | date = August 1993 | pmid = 8354269 | doi = 10.1111/j.1432-1033.1993.tb18074.x }}</ref><ref>{{cite journal | vauthors = Wood HG | title = Life with CO or CO2 and H2 as a source of carbon and energy | journal = FASEB Journal | volume = 5 | issue = 2 | pages = 156–63 | date = February 1991 | pmid = 1900793 | doi = 10.1096/fasebj.5.2.1900793 | s2cid = 45967404 }}</ref>，但它们利用无机化合物的能量来驱动反应<ref>{{cite journal | vauthors = Shively JM, van Keulen G, Meijer WG | title = Something from almost nothing: carbon dioxide fixation in chemoautotrophs | journal = Annual Review of Microbiology | volume = 52 | issue =  | pages = 191–230 | year = 1998 | pmid = 9891798 | doi = 10.1146/annurev.micro.52.1.191 }}</ref>。

===Carbohydrates and glycans===

===碳水化合物和聚糖 ===

{{further|Gluconeogenesis|Glyoxylate cycle|Glycogenesis|Glycosylation}}

{{further|Gluconeogenesis|Glyoxylate cycle|Glycogenesis|Glycosylation}}

多糖和聚糖是在糖基转移酶作用下，将单糖从活性糖-磷酸盐供体（如尿苷二磷酸葡萄糖(UDP-Glc)）依次加入到生长中的多糖的受体羟基上形成的。由于底物环上的任何羟基都可以作为受体，所以产生的多糖会有直链或支链结构<ref>{{cite book |last1=Freeze|first1=Hudson H. | name-list-style = vanc | chapter =Glycosylation Precursors|date=2015|url=http://www.ncbi.nlm.nih.gov/books/NBK453043/| title = Essentials of Glycobiology|editor-last=Varki|editor-first=Ajit|edition=3rd|place=Cold Spring Harbor (NY)|publisher=Cold Spring Harbor Laboratory Press|pmid=28876856|access-date=2020-07-08|last2=Hart|first2=Gerald W.|last3=Schnaar|first3=Ronald L.|doi=10.1101/glycobiology.3e.005 |doi-broken-date=1 November 2020 |editor2-last=Cummings|editor2-first=Richard D.|editor3-last=Esko|editor3-first=Jeffrey D.|editor4-last=Stanley|editor4-first=Pamela }}</ref>。产生的多糖本身具有结构或代谢功能，还可以通过低聚糖转移酶转移到脂质和蛋白质中<ref>{{cite journal | vauthors = Opdenakker G, Rudd PM, Ponting CP, Dwek RA | title = Concepts and principles of glycobiology | journal = FASEB Journal | volume = 7 | issue = 14 | pages = 1330–7 | date = November 1993 | pmid = 8224606 | doi = 10.1096/fasebj.7.14.8224606 | s2cid = 10388991 }}</ref><ref>{{cite journal | vauthors = McConville MJ, Menon AK | title = Recent developments in the cell biology and biochemistry of glycosylphosphatidylinositol lipids (review) | journal = Molecular Membrane Biology | volume = 17 | issue = 1 | pages = 1–16 | year = 2000 | pmid = 10824734 | doi = 10.1080/096876800294443 | doi-access = free }}</ref>。

多糖和聚糖是在糖基转移酶作用下，将单糖从活性糖-磷酸盐供体（如尿苷二磷酸葡萄糖(UDP-Glc)）依次加入到生长中的多糖的受体羟基上形成的。由于底物环上的任何羟基都可以作为受体，所以产生的多糖会有直链或支链结构<ref>{{cite book |last1=Freeze|first1=Hudson H. | name-list-style = vanc | chapter =Glycosylation Precursors|date=2015|url=http://www.ncbi.nlm.nih.gov/books/NBK453043/| title = Essentials of Glycobiology|editor-last=Varki|editor-first=Ajit|edition=3rd|place=Cold Spring Harbor (NY)|publisher=Cold Spring Harbor Laboratory Press|pmid=28876856|access-date=2020-07-08|last2=Hart|first2=Gerald W.|last3=Schnaar|first3=Ronald L.|doi=10.1101/glycobiology.3e.005 |doi-broken-date=1 November 2020 |editor2-last=Cummings|editor2-first=Richard D.|editor3-last=Esko|editor3-first=Jeffrey D.|editor4-last=Stanley|editor4-first=Pamela }}</ref>。产生的多糖本身具有结构或代谢功能，还可以通过低聚糖转移酶转移到脂质和蛋白质中<ref>{{cite journal | vauthors = Opdenakker G, Rudd PM, Ponting CP, Dwek RA | title = Concepts and principles of glycobiology | journal = FASEB Journal | volume = 7 | issue = 14 | pages = 1330–7 | date = November 1993 | pmid = 8224606 | doi = 10.1096/fasebj.7.14.8224606 | s2cid = 10388991 }}</ref><ref>{{cite journal | vauthors = McConville MJ, Menon AK | title = Recent developments in the cell biology and biochemistry of glycosylphosphatidylinositol lipids (review) | journal = Molecular Membrane Biology | volume = 17 | issue = 1 | pages = 1–16 | year = 2000 | pmid = 10824734 | doi = 10.1080/096876800294443 | doi-access = free }}</ref>。

 

===脂肪酸，类异戊二烯和固醇===

 

 

===Fatty acids, isoprenoids and sterol===

 

{{further|Fatty acid synthesis|Steroid metabolism}}

{{further|Fatty acid synthesis|Steroid metabolism}}

萜烯和异戊二烯是一大类脂类，包括类胡萝卜素，也是最大的一类植物天然产品<ref>{{cite journal | vauthors = Dubey VS, Bhalla R, Luthra R | title = An overview of the non-mevalonate pathway for terpenoid biosynthesis in plants | journal = Journal of Biosciences | volume = 28 | issue = 5 | pages = 637–46 | date = September 2003 | pmid = 14517367 | doi = 10.1007/BF02703339 | url = http://www.ias.ac.in/jbiosci/sep2003/637.pdf | url-status = dead | s2cid = 27523830 | archive-url = https://web.archive.org/web/20070415213325/http://www.ias.ac.in/jbiosci/sep2003/637.pdf | df =  | archive-date = 15 April 2007 }}</ref>。这些化合物是由反应性前体焦磷酸异戊烯酯和焦磷酸二甲基烯丙基酯所提供的异戊二烯单元组装和改性而成。这些前体可以靠不同的途径制造<ref name=Kuzuyama>{{cite journal | vauthors = Kuzuyama T, Seto H | title = Diversity of the biosynthesis of the isoprene units | journal = Natural Product Reports | volume = 20 | issue = 2 | pages = 171–83 | date = April 2003 | pmid = 12735695 | doi = 10.1039/b109860h }}</ref>。在动物和古生物中，甲戊二酸途径从乙酰辅酶A产生这些化合物<ref>{{cite journal | vauthors = Grochowski LL, Xu H, White RH | title = Methanocaldococcus jannaschii uses a modified mevalonate pathway for biosynthesis of isopentenyl diphosphate | journal = Journal of Bacteriology | volume = 188 | issue = 9 | pages = 3192–8 | date = May 2006 | pmid = 16621811 | pmc = 1447442 | doi = 10.1128/JB.188.9.3192-3198.2006 }}</ref>，而在植物和细菌中，非甲戊二酸途径使用丙酮酸和甘油醛3-磷酸作为底物。使用这些活化的异戊二烯供体的一个重要反应是固醇的生物合成<ref name=Kuzuyama/><ref>{{cite journal | vauthors = Lichtenthaler HK | title = The 1-Deoxy-D-Xylulose-5-Phosphate Pathway of Isoprenoid Biosynthesis in Plants | journal = Annual Review of Plant Physiology and Plant Molecular Biology | volume = 50 | issue =  | pages = 47–65 | date = June 1999 | pmid = 15012203 | doi = 10.1146/annurev.arplant.50.1.47 }}</ref>。在该反应中，异戊二烯单元连接在一起，制成角鲨烯，然后折叠起来形成一组环，制成羊毛固醇<ref name=Schroepfer>{{cite journal | vauthors = Schroepfer GJ | title = Sterol biosynthesis | journal = Annual Review of Biochemistry | volume = 50 | issue =  | pages = 585–621 | year = 1981 | pmid = 7023367 | doi = 10.1146/annurev.bi.50.070181.003101 }}</ref>。羊毛固醇随后可转化为其他固醇，如胆固醇和麦角固醇<ref name=Schroepfer/><ref>{{cite journal | vauthors = Lees ND, Skaggs B, Kirsch DR, Bard M | title = Cloning of the late genes in the ergosterol biosynthetic pathway of Saccharomyces cerevisiae--a review | journal = Lipids | volume = 30 | issue = 3 | pages = 221–6 | date = March 1995 | pmid = 7791529 | doi = 10.1007/BF02537824 | s2cid = 4019443 }}</ref>。

萜烯和异戊二烯是一大类脂类，包括类胡萝卜素，也是最大的一类植物天然产品<ref>{{cite journal | vauthors = Dubey VS, Bhalla R, Luthra R | title = An overview of the non-mevalonate pathway for terpenoid biosynthesis in plants | journal = Journal of Biosciences | volume = 28 | issue = 5 | pages = 637–46 | date = September 2003 | pmid = 14517367 | doi = 10.1007/BF02703339 | url = http://www.ias.ac.in/jbiosci/sep2003/637.pdf | url-status = dead | s2cid = 27523830 | archive-url = https://web.archive.org/web/20070415213325/http://www.ias.ac.in/jbiosci/sep2003/637.pdf | df =  | archive-date = 15 April 2007 }}</ref>。这些化合物是由反应性前体焦磷酸异戊烯酯和焦磷酸二甲基烯丙基酯所提供的异戊二烯单元组装和改性而成。这些前体可以靠不同的途径制造<ref name=Kuzuyama>{{cite journal | vauthors = Kuzuyama T, Seto H | title = Diversity of the biosynthesis of the isoprene units | journal = Natural Product Reports | volume = 20 | issue = 2 | pages = 171–83 | date = April 2003 | pmid = 12735695 | doi = 10.1039/b109860h }}</ref>。在动物和古生物中，甲戊二酸途径从乙酰辅酶A产生这些化合物<ref>{{cite journal | vauthors = Grochowski LL, Xu H, White RH | title = Methanocaldococcus jannaschii uses a modified mevalonate pathway for biosynthesis of isopentenyl diphosphate | journal = Journal of Bacteriology | volume = 188 | issue = 9 | pages = 3192–8 | date = May 2006 | pmid = 16621811 | pmc = 1447442 | doi = 10.1128/JB.188.9.3192-3198.2006 }}</ref>，而在植物和细菌中，非甲戊二酸途径使用丙酮酸和甘油醛3-磷酸作为底物。使用这些活化的异戊二烯供体的一个重要反应是固醇的生物合成<ref name=Kuzuyama/><ref>{{cite journal | vauthors = Lichtenthaler HK | title = The 1-Deoxy-D-Xylulose-5-Phosphate Pathway of Isoprenoid Biosynthesis in Plants | journal = Annual Review of Plant Physiology and Plant Molecular Biology | volume = 50 | issue =  | pages = 47–65 | date = June 1999 | pmid = 15012203 | doi = 10.1146/annurev.arplant.50.1.47 }}</ref>。在该反应中，异戊二烯单元连接在一起，制成角鲨烯，然后折叠起来形成一组环，制成羊毛固醇<ref name=Schroepfer>{{cite journal | vauthors = Schroepfer GJ | title = Sterol biosynthesis | journal = Annual Review of Biochemistry | volume = 50 | issue =  | pages = 585–621 | year = 1981 | pmid = 7023367 | doi = 10.1146/annurev.bi.50.070181.003101 }}</ref>。羊毛固醇随后可转化为其他固醇，如胆固醇和麦角固醇<ref name=Schroepfer/><ref>{{cite journal | vauthors = Lees ND, Skaggs B, Kirsch DR, Bard M | title = Cloning of the late genes in the ergosterol biosynthetic pathway of Saccharomyces cerevisiae--a review | journal = Lipids | volume = 30 | issue = 3 | pages = 221–6 | date = March 1995 | pmid = 7791529 | doi = 10.1007/BF02537824 | s2cid = 4019443 }}</ref>。

===Proteins===

===蛋白质类 ===

{{further|Protein biosynthesis|Amino acid synthesis}}

{{further|Protein biosynthesis|Amino acid synthesis}}

氨基酸通过肽键链连接成蛋白质。每种不同的蛋白质都有一个独特的氨基酸残基序列：这就是它的主要结构。就像字母表的字母可以组合成无穷无尽的各种单词一样，氨基酸也能以不同的序列连接起来，形成种类繁多的蛋白质。蛋白质是由氨基酸制成的，这些氨基酸通过酯键附着在转运RNA(tRNA)分子上而被激活。氨基酰tRNA前体是在靠氨基酰tRNA合成酶进行的ATP依赖性反应中产生的.<ref>{{cite journal | vauthors = Ibba M, Söll D | title = The renaissance of aminoacyl-tRNA synthesis | journal = EMBO Reports | volume = 2 | issue = 5 | pages = 382–7 | date = May 2001 | pmid = 11375928 | pmc = 1083889 | doi = 10.1093/embo-reports/kve095 | url = http://www.molcells.org/home/journal/include/downloadPdf.asp?articleuid={A158E3B4-2423-4806-9A30-4B93CDA76DA0} | url-status = dead | archive-url = https://web.archive.org/web/20110501181419/http://www.molcells.org/home/journal/include/downloadPdf.asp?articleuid=%7BA158E3B4-2423-4806-9A30-4B93CDA76DA0%7D | df =  | archive-date = 1 May 2011 }}</ref>。然后，这种氨基酰tRNA成为核糖体的底物，核糖体利用信使RNA中的序列信息将氨基酸连接到伸长的蛋白质链上<ref>{{cite journal | vauthors = Lengyel P, Söll D | title = Mechanism of protein biosynthesis | journal = Bacteriological Reviews | volume = 33 | issue = 2 | pages = 264–301 | date = June 1969 | pmid = 4896351 | pmc = 378322 | doi = 10.1128/MMBR.33.2.264-301.1969 }}</ref>。

氨基酸通过肽键链连接成蛋白质。每种不同的蛋白质都有一个独特的氨基酸残基序列：这就是它的主要结构。就像字母表的字母可以组合成无穷无尽的各种单词一样，氨基酸也能以不同的序列连接起来，形成种类繁多的蛋白质。蛋白质是由氨基酸制成的，这些氨基酸通过酯键附着在转运RNA(tRNA)分子上而被激活。氨基酰tRNA前体是在靠氨基酰tRNA合成酶进行的ATP依赖性反应中产生的.<ref>{{cite journal | vauthors = Ibba M, Söll D | title = The renaissance of aminoacyl-tRNA synthesis | journal = EMBO Reports | volume = 2 | issue = 5 | pages = 382–7 | date = May 2001 | pmid = 11375928 | pmc = 1083889 | doi = 10.1093/embo-reports/kve095 | url = http://www.molcells.org/home/journal/include/downloadPdf.asp?articleuid={A158E3B4-2423-4806-9A30-4B93CDA76DA0} | url-status = dead | archive-url = https://web.archive.org/web/20110501181419/http://www.molcells.org/home/journal/include/downloadPdf.asp?articleuid=%7BA158E3B4-2423-4806-9A30-4B93CDA76DA0%7D | df =  | archive-date = 1 May 2011 }}</ref>。然后，这种氨基酰tRNA成为核糖体的底物，核糖体利用信使RNA中的序列信息将氨基酸连接到伸长的蛋白质链上<ref>{{cite journal | vauthors = Lengyel P, Söll D | title = Mechanism of protein biosynthesis | journal = Bacteriological Reviews | volume = 33 | issue = 2 | pages = 264–301 | date = June 1969 | pmid = 4896351 | pmc = 378322 | doi = 10.1128/MMBR.33.2.264-301.1969 }}</ref>。

===Nucleotide synthesis and salvage===

===核苷酸的合成和补救途径 ===

{{further|Nucleotide salvage|Pyrimidine biosynthesis|Purine#Metabolism}}

{{further|Nucleotide salvage|Pyrimidine biosynthesis|Purine#Metabolism}}

核苷酸由氨基酸、二氧化碳和甲酸在需要大量代谢能量的途径中生成<ref name=Rudolph>{{cite journal | vauthors = Rudolph FB | title = The biochemistry and physiology of nucleotides | journal = The Journal of Nutrition | volume = 124 | issue = 1 Suppl | pages = 124S–127S | date = January 1994 | pmid = 8283301 | doi = 10.1093/jn/124.suppl_1.124S }} {{cite journal | vauthors = Zrenner R, Stitt M, Sonnewald U, Boldt R | title = Pyrimidine and purine biosynthesis and degradation in plants | journal = Annual Review of Plant Biology | volume = 57 | issue =  | pages = 805–36 | year = 2006 | pmid = 16669783 | doi = 10.1146/annurev.arplant.57.032905.105421 }}</ref>。因此，大多数生物体都有有效的系统来挽救预先形成的核苷酸<ref name=Rudolph/><ref>{{cite journal | vauthors = Stasolla C, Katahira R, Thorpe TA, Ashihara H | title = Purine and pyrimidine nucleotide metabolism in higher plants | journal = Journal of Plant Physiology | volume = 160 | issue = 11 | pages = 1271–95 | date = November 2003 | pmid = 14658380 | doi = 10.1078/0176-1617-01169 }}</ref>。嘌呤以核苷的形式合成(碱基附着在核糖上)。腺嘌呤和鸟嘌呤都是由一磷酸核苷肌苷前体合成的<ref name="pmid 22531138">{{cite journal | vauthors = Davies O, Mendes P, Smallbone K, Malys N | title = Characterisation of multiple substrate-specific (d)ITP/(d)XTPase and modelling of deaminated purine nucleotide metabolism | journal = BMB Reports | volume = 45 | issue = 4 | pages = 259–64 | date = April 2012 | pmid = 22531138 | doi = 10.5483/BMBRep.2012.45.4.259 | url = http://wrap.warwick.ac.uk/49510/1/WRAP_Malys_%5B45-4%5D1204261917_%28259-264%29BMB_11-169.pdf }}</ref>，而前体是由甘氨酸、谷氨酰胺和天冬氨酸的原子合成的，从辅酶四氢叶酸转移来的甲酸酯也是如此。另一方面，嘧啶是由磷酸基合成的，而磷酸基是由谷氨酰胺和天门冬氨酸形成的<ref>{{cite journal | vauthors = Smith JL | title = Enzymes of nucleotide synthesis | journal = Current Opinion in Structural Biology | volume = 5 | issue = 6 | pages = 752–7 | date = December 1995 | pmid = 8749362 | doi = 10.1016/0959-440X(95)80007-7 }}</ref>。

核苷酸由氨基酸、二氧化碳和甲酸在需要大量代谢能量的途径中生成<ref name=Rudolph>{{cite journal | vauthors = Rudolph FB | title = The biochemistry and physiology of nucleotides | journal = The Journal of Nutrition | volume = 124 | issue = 1 Suppl | pages = 124S–127S | date = January 1994 | pmid = 8283301 | doi = 10.1093/jn/124.suppl_1.124S }} {{cite journal | vauthors = Zrenner R, Stitt M, Sonnewald U, Boldt R | title = Pyrimidine and purine biosynthesis and degradation in plants | journal = Annual Review of Plant Biology | volume = 57 | issue =  | pages = 805–36 | year = 2006 | pmid = 16669783 | doi = 10.1146/annurev.arplant.57.032905.105421 }}</ref>。因此，大多数生物体都有有效的系统来挽救预先形成的核苷酸<ref name=Rudolph/><ref>{{cite journal | vauthors = Stasolla C, Katahira R, Thorpe TA, Ashihara H | title = Purine and pyrimidine nucleotide metabolism in higher plants | journal = Journal of Plant Physiology | volume = 160 | issue = 11 | pages = 1271–95 | date = November 2003 | pmid = 14658380 | doi = 10.1078/0176-1617-01169 }}</ref>。嘌呤以核苷的形式合成(碱基附着在核糖上)。腺嘌呤和鸟嘌呤都是由一磷酸核苷肌苷前体合成的<ref name="pmid 22531138">{{cite journal | vauthors = Davies O, Mendes P, Smallbone K, Malys N | title = Characterisation of multiple substrate-specific (d)ITP/(d)XTPase and modelling of deaminated purine nucleotide metabolism | journal = BMB Reports | volume = 45 | issue = 4 | pages = 259–64 | date = April 2012 | pmid = 22531138 | doi = 10.5483/BMBRep.2012.45.4.259 | url = http://wrap.warwick.ac.uk/49510/1/WRAP_Malys_%5B45-4%5D1204261917_%28259-264%29BMB_11-169.pdf }}</ref>，而前体是由甘氨酸、谷氨酰胺和天冬氨酸的原子合成的，从辅酶四氢叶酸转移来的甲酸酯也是如此。另一方面，嘧啶是由磷酸基合成的，而磷酸基是由谷氨酰胺和天门冬氨酸形成的<ref>{{cite journal | vauthors = Smith JL | title = Enzymes of nucleotide synthesis | journal = Current Opinion in Structural Biology | volume = 5 | issue = 6 | pages = 752–7 | date = December 1995 | pmid = 8749362 | doi = 10.1016/0959-440X(95)80007-7 }}</ref>。

==Xenobiotics and redox metabolism==

==异种生物学和氧化还原代谢 ==

{{further|Xenobiotic metabolism|Drug metabolism|Alcohol metabolism|Antioxidant}}

{{further|Xenobiotic metabolism|Drug metabolism|Alcohol metabolism|Antioxidant}}

对于好氧生物来说，一个相关的问题是氧化应激<ref name=Davies>{{cite journal | vauthors = Davies KJ | title = Oxidative stress: the paradox of aerobic life | journal = Biochemical Society Symposium | volume = 61 | issue =  | pages = 1–31 | year = 1995 | pmid = 8660387 | doi = 10.1042/bss0610001 }}</ref>。这个过程包括氧化磷酸化和蛋白质折叠时二硫键的形成，它产生了活性氧类（如过氧化氢）<ref>{{cite journal | vauthors = Tu BP, Weissman JS | title = Oxidative protein folding in eukaryotes: mechanisms and consequences | journal = The Journal of Cell Biology | volume = 164 | issue = 3 | pages = 341–6 | date = February 2004 | pmid = 14757749 | pmc = 2172237 | doi = 10.1083/jcb.200311055 }}</ref>。这些破坏性的氧化剂被抗氧化代谢物（如谷胱甘肽和酶）和酶（如过氧化氢酶和过氧化物酶）去除<ref name=Sies>{{cite journal | vauthors = Sies H | title = Oxidative stress: oxidants and antioxidants | journal = Experimental Physiology | volume = 82 | issue = 2 | pages = 291–5 | date = March 1997 | pmid = 9129943 | doi = 10.1113/expphysiol.1997.sp004024 | s2cid = 20240552 | url = http://ep.physoc.org/cgi/reprint/82/2/291.pdf | access-date = 9 March 2007 | url-status = dead | archive-url = https://web.archive.org/web/20090325001126/http://ep.physoc.org/cgi/reprint/82/2/291.pdf | archive-date = 25 March 2009 }}</ref><ref name=Vertuani>{{cite journal | vauthors = Vertuani S, Angusti A, Manfredini S | title = The antioxidants and pro-antioxidants network: an overview | journal = Current Pharmaceutical Design | volume = 10 | issue = 14 | pages = 1677–94 | year = 2004 | pmid = 15134565 | doi = 10.2174/1381612043384655 | s2cid = 43713549 }}</ref>。

对于好氧生物来说，一个相关的问题是氧化应激<ref name=Davies>{{cite journal | vauthors = Davies KJ | title = Oxidative stress: the paradox of aerobic life | journal = Biochemical Society Symposium | volume = 61 | issue =  | pages = 1–31 | year = 1995 | pmid = 8660387 | doi = 10.1042/bss0610001 }}</ref>。这个过程包括氧化磷酸化和蛋白质折叠时二硫键的形成，它产生了活性氧类（如过氧化氢）<ref>{{cite journal | vauthors = Tu BP, Weissman JS | title = Oxidative protein folding in eukaryotes: mechanisms and consequences | journal = The Journal of Cell Biology | volume = 164 | issue = 3 | pages = 341–6 | date = February 2004 | pmid = 14757749 | pmc = 2172237 | doi = 10.1083/jcb.200311055 }}</ref>。这些破坏性的氧化剂被抗氧化代谢物（如谷胱甘肽和酶）和酶（如过氧化氢酶和过氧化物酶）去除<ref name=Sies>{{cite journal | vauthors = Sies H | title = Oxidative stress: oxidants and antioxidants | journal = Experimental Physiology | volume = 82 | issue = 2 | pages = 291–5 | date = March 1997 | pmid = 9129943 | doi = 10.1113/expphysiol.1997.sp004024 | s2cid = 20240552 | url = http://ep.physoc.org/cgi/reprint/82/2/291.pdf | access-date = 9 March 2007 | url-status = dead | archive-url = https://web.archive.org/web/20090325001126/http://ep.physoc.org/cgi/reprint/82/2/291.pdf | archive-date = 25 March 2009 }}</ref><ref name=Vertuani>{{cite journal | vauthors = Vertuani S, Angusti A, Manfredini S | title = The antioxidants and pro-antioxidants network: an overview | journal = Current Pharmaceutical Design | volume = 10 | issue = 14 | pages = 1677–94 | year = 2004 | pmid = 15134565 | doi = 10.2174/1381612043384655 | s2cid = 43713549 }}</ref>。

==Thermodynamics of living organisms==

==生命有机体的热力学 ==

{{further|Biological thermodynamics}}

{{further|Biological thermodynamics}}

生命有机体一定会遵守热力学定律，该定律描述了热量和功的传递。热力学第二定律指出，在任何封闭系统中，熵的总量（混乱度）不会减少。尽管生物体惊人的复杂性似乎与这一定律相矛盾，但生命是可能的，因为它们是与环境交换物质和能量的开放系统。也就是说，生命系统并不处于平衡状态，而是耗散系统，它通过大量增加环境熵来维持其高度复杂的状态<ref>{{cite journal | vauthors = von Stockar U, Liu J | title = Does microbial life always feed on negative entropy? Thermodynamic analysis of microbial growth | journal = Biochimica et Biophysica Acta (BBA) - Bioenergetics | volume = 1412 | issue = 3 | pages = 191–211 | date = August 1999 | pmid = 10482783 | doi = 10.1016/S0005-2728(99)00065-1 }}</ref>。细胞的新陈代谢通过将分解代谢的自发过程和合成代谢的非自发过程进行耦合来实现这一点。从热力学的角度来看，新陈代谢通过制造混乱来维持秩序<ref>{{cite journal | vauthors = Demirel Y, Sandler SI | title = Thermodynamics and bioenergetics | journal = Biophysical Chemistry | volume = 97 | issue = 2–3 | pages = 87–111 | date = June 2002 | pmid = 12050002 | doi = 10.1016/S0301-4622(02)00069-8 | url = https://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=1006&context=chemengthermalmech }}</ref>。

生命有机体一定会遵守热力学定律，该定律描述了热量和功的传递。热力学第二定律指出，在任何封闭系统中，熵的总量（混乱度）不会减少。尽管生物体惊人的复杂性似乎与这一定律相矛盾，但生命是可能的，因为它们是与环境交换物质和能量的开放系统。也就是说，生命系统并不处于平衡状态，而是耗散系统，它通过大量增加环境熵来维持其高度复杂的状态<ref>{{cite journal | vauthors = von Stockar U, Liu J | title = Does microbial life always feed on negative entropy? Thermodynamic analysis of microbial growth | journal = Biochimica et Biophysica Acta (BBA) - Bioenergetics | volume = 1412 | issue = 3 | pages = 191–211 | date = August 1999 | pmid = 10482783 | doi = 10.1016/S0005-2728(99)00065-1 }}</ref>。细胞的新陈代谢通过将分解代谢的自发过程和合成代谢的非自发过程进行耦合来实现这一点。从热力学的角度来看，新陈代谢通过制造混乱来维持秩序<ref>{{cite journal | vauthors = Demirel Y, Sandler SI | title = Thermodynamics and bioenergetics | journal = Biophysical Chemistry | volume = 97 | issue = 2–3 | pages = 87–111 | date = June 2002 | pmid = 12050002 | doi = 10.1016/S0301-4622(02)00069-8 | url = https://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=1006&context=chemengthermalmech }}</ref>。

==Regulation and control==

==调控 ==

{{further|Metabolic pathway|Metabolic control analysis|Hormone|Regulatory enzymes|Cell signaling}}

{{further|Metabolic pathway|Metabolic control analysis|Hormone|Regulatory enzymes|Cell signaling}}

一个非常好理解的外在控制的例子是激素胰岛素对葡萄糖代谢的调节<ref>{{cite journal | vauthors = Lienhard GE, Slot JW, James DE, Mueckler MM | title = How cells absorb glucose | journal = Scientific American | volume = 266 | issue = 1 | pages = 86–91 | date = January 1992 | pmid = 1734513 | doi = 10.1038/scientificamerican0192-86 | bibcode = 1992SciAm.266a..86L }}</ref>。胰岛素是在血糖升高时产生的。胰岛素与细胞上的胰岛素受体结合，然后激活一连串的蛋白激酶，使细胞吸收葡萄糖，并将其转化为储存分子（如脂肪酸和糖原）<ref>{{cite journal | vauthors = Roach PJ | title = Glycogen and its metabolism | journal = Current Molecular Medicine | volume = 2 | issue = 2 | pages = 101–20 | date = March 2002 | pmid = 11949930 | doi = 10.2174/1566524024605761 }}</ref>。糖原的新陈代谢受到分解糖原的磷酸化酶和制造糖原的糖原合成酶的活性控制。这些酶的调节方式是相互的，磷酸化作用抑制糖原合成酶，但激活磷酸化酶。胰岛素通过激活蛋白磷酸酶使这些酶的磷酸化程度降低，从而触发糖原合成<ref>{{cite journal | vauthors = Newgard CB, Brady MJ, O'Doherty RM, Saltiel AR | title = Organizing glucose disposal: emerging roles of the glycogen targeting subunits of protein phosphatase-1 | journal = Diabetes | volume = 49 | issue = 12 | pages = 1967–77 | date = December 2000 | pmid = 11117996 | doi = 10.2337/diabetes.49.12.1967 | url = http://diabetes.diabetesjournals.org/cgi/reprint/49/12/1967.pdf }}</ref>。

一个非常好理解的外在控制的例子是激素胰岛素对葡萄糖代谢的调节<ref>{{cite journal | vauthors = Lienhard GE, Slot JW, James DE, Mueckler MM | title = How cells absorb glucose | journal = Scientific American | volume = 266 | issue = 1 | pages = 86–91 | date = January 1992 | pmid = 1734513 | doi = 10.1038/scientificamerican0192-86 | bibcode = 1992SciAm.266a..86L }}</ref>。胰岛素是在血糖升高时产生的。胰岛素与细胞上的胰岛素受体结合，然后激活一连串的蛋白激酶，使细胞吸收葡萄糖，并将其转化为储存分子（如脂肪酸和糖原）<ref>{{cite journal | vauthors = Roach PJ | title = Glycogen and its metabolism | journal = Current Molecular Medicine | volume = 2 | issue = 2 | pages = 101–20 | date = March 2002 | pmid = 11949930 | doi = 10.2174/1566524024605761 }}</ref>。糖原的新陈代谢受到分解糖原的磷酸化酶和制造糖原的糖原合成酶的活性控制。这些酶的调节方式是相互的，磷酸化作用抑制糖原合成酶，但激活磷酸化酶。胰岛素通过激活蛋白磷酸酶使这些酶的磷酸化程度降低，从而触发糖原合成<ref>{{cite journal | vauthors = Newgard CB, Brady MJ, O'Doherty RM, Saltiel AR | title = Organizing glucose disposal: emerging roles of the glycogen targeting subunits of protein phosphatase-1 | journal = Diabetes | volume = 49 | issue = 12 | pages = 1967–77 | date = December 2000 | pmid = 11117996 | doi = 10.2337/diabetes.49.12.1967 | url = http://diabetes.diabetesjournals.org/cgi/reprint/49/12/1967.pdf }}</ref>。

==Evolution==

==演化 ==

{{further|Molecular evolution|Phylogenetics}}

{{further|Molecular evolution|Phylogenetics}}

除了新的代谢途径的进化，演化也会导致代谢功能的丧失。例如，在某些寄生物中，一些并非生存必需的代谢过程丢失了，而预先形成的氨基酸、核苷酸和碳水化合物可能会从寄主那里被清除<ref>{{cite journal | vauthors = Lawrence JG | title = Common themes in the genome strategies of pathogens | journal = Current Opinion in Genetics & Development | volume = 15 | issue = 6 | pages = 584–8 | date = December 2005 | pmid = 16188434 | doi = 10.1016/j.gde.2005.09.007 }} {{cite journal | vauthors = Wernegreen JJ | title = For better or worse: genomic consequences of intracellular mutualism and parasitism | journal = Current Opinion in Genetics & Development | volume = 15 | issue = 6 | pages = 572–83 | date = December 2005 | pmid = 16230003 | doi = 10.1016/j.gde.2005.09.013 }}</ref>。在内共生生物体中也可以看到类似的代谢能力下降<ref>{{cite journal | vauthors = Pál C, Papp B, Lercher MJ, Csermely P, Oliver SG, Hurst LD | title = Chance and necessity in the evolution of minimal metabolic networks | journal = Nature | volume = 440 | issue = 7084 | pages = 667–70 | date = March 2006 | pmid = 16572170 | doi = 10.1038/nature04568 | s2cid = 4424895 | bibcode = 2006Natur.440..667P }}</ref>。

除了新的代谢途径的进化，演化也会导致代谢功能的丧失。例如，在某些寄生物中，一些并非生存必需的代谢过程丢失了，而预先形成的氨基酸、核苷酸和碳水化合物可能会从寄主那里被清除<ref>{{cite journal | vauthors = Lawrence JG | title = Common themes in the genome strategies of pathogens | journal = Current Opinion in Genetics & Development | volume = 15 | issue = 6 | pages = 584–8 | date = December 2005 | pmid = 16188434 | doi = 10.1016/j.gde.2005.09.007 }} {{cite journal | vauthors = Wernegreen JJ | title = For better or worse: genomic consequences of intracellular mutualism and parasitism | journal = Current Opinion in Genetics & Development | volume = 15 | issue = 6 | pages = 572–83 | date = December 2005 | pmid = 16230003 | doi = 10.1016/j.gde.2005.09.013 }}</ref>。在内共生生物体中也可以看到类似的代谢能力下降<ref>{{cite journal | vauthors = Pál C, Papp B, Lercher MJ, Csermely P, Oliver SG, Hurst LD | title = Chance and necessity in the evolution of minimal metabolic networks | journal = Nature | volume = 440 | issue = 7084 | pages = 667–70 | date = March 2006 | pmid = 16572170 | doi = 10.1038/nature04568 | s2cid = 4424895 | bibcode = 2006Natur.440..667P }}</ref>。

==Investigation and manipulation==

==调查和操纵 ==

{{further|Protein methods|Proteomics|Metabolomics|Metabolic network modelling}}

{{further|Protein methods|Proteomics|Metabolomics|Metabolic network modelling}}

{{cite journal | vauthors = Krämer M, Bongaerts J, Bovenberg R, Kremer S, Müller U, Orf S, Wubbolts M, Raeven L | display-authors = 6 | title = Metabolic engineering for microbial production of shikimic acid | journal = Metabolic Engineering | volume = 5 | issue = 4 | pages = 277–83 | date = October 2003 | pmid = 14642355 | doi = 10.1016/j.ymben.2003.09.001 }}</ref>。这些基因改造通常旨在减少生产产品所使用的能源，提高产量和减少废物的产生<ref>{{cite journal | vauthors = Koffas M, Roberge C, Lee K, Stephanopoulos G | title = Metabolic engineering | journal = Annual Review of Biomedical Engineering | volume = 1 | issue =  | pages = 535–57 | year = 1999 | pmid = 11701499 | doi = 10.1146/annurev.bioeng.1.1.535 | s2cid = 11814282 }}</ref>。

{{cite journal | vauthors = Krämer M, Bongaerts J, Bovenberg R, Kremer S, Müller U, Orf S, Wubbolts M, Raeven L | display-authors = 6 | title = Metabolic engineering for microbial production of shikimic acid | journal = Metabolic Engineering | volume = 5 | issue = 4 | pages = 277–83 | date = October 2003 | pmid = 14642355 | doi = 10.1016/j.ymben.2003.09.001 }}</ref>。这些基因改造通常旨在减少生产产品所使用的能源，提高产量和减少废物的产生<ref>{{cite journal | vauthors = Koffas M, Roberge C, Lee K, Stephanopoulos G | title = Metabolic engineering | journal = Annual Review of Biomedical Engineering | volume = 1 | issue =  | pages = 535–57 | year = 1999 | pmid = 11701499 | doi = 10.1146/annurev.bioeng.1.1.535 | s2cid = 11814282 }}</ref>。

==History==

==历史 ==

{{further|History of biochemistry|History of molecular biology}}

{{further|History of biochemistry|History of molecular biology}}

===Greek philosophy===

===希腊哲学 ===

[[Aristotle]]'s ''[[The Parts of Animals]]'' sets out enough details of [[Aristotle's biology|his views on metabolism]] for an open flow model to be made. He believed that at each stage of the process, materials from food were transformed, with heat being released as the [[classical element]] of fire, and residual materials being excreted as urine, bile, or faeces.

[[Aristotle]]'s ''[[The Parts of Animals]]'' sets out enough details of [[Aristotle's biology|his views on metabolism]] for an open flow model to be made. He believed that at each stage of the process, materials from food were transformed, with heat being released as the [[classical element]] of fire, and residual materials being excreted as urine, bile, or faeces.

Aristotle's The Parts of Animals sets out enough details of his views on metabolism for an open flow model to be made. He believed that at each stage of the process, materials from food were transformed, with heat being released as the classical element of fire, and residual materials being excreted as urine, bile, or faeces.

Aristotle's The Parts of Animals sets out enough details of his views on metabolism for an open flow model to be made. He believed that at each stage of the process, materials from food were transformed, with heat being released as the classical element of fire, and residual materials being excreted as urine, bile, or faeces.

Aristotle的《动物的各部分》详细阐述了他关于新陈代谢的观点，以便建立一个开放性的流动模型。他认为，在这个过程的每个阶段，来自食物的物质都会发生转化，释放出的热量成为火的典型元素，残余物质以尿液、胆汁或粪便的形式排出体外<ref>{{cite book|author=Leroi, Armand Marie|url=https://archive.org/stream/lagoonhowaristot0000lero?ref=ol#page/402/mode/2up|title=The Lagoon: How Aristotle Invented Science|date=2014|publisher=Bloomsbury|isbn=978-1-4088-3622-4|location=|pages=400–401|authorlink=Armand Marie Leroi}}</ref>。

亚里士多德的《动物的各部分》详细阐述了他关于新陈代谢的观点，以便建立一个开放性的流动模型。他认为，在这个过程的每个阶段，来自食物的物质都会发生转化，释放出的热量成为火的典型元素，残余物质以尿液、胆汁或粪便的形式排出体外<ref>{{cite book|author=Leroi, Armand Marie|url=https://archive.org/stream/lagoonhowaristot0000lero?ref=ol#page/402/mode/2up|title=The Lagoon: How Aristotle Invented Science|date=2014|publisher=Bloomsbury|isbn=978-1-4088-3622-4|location=|pages=400–401|authorlink=Armand Marie Leroi}}</ref>。

===Islamic medicine===

===伊斯兰医学 ===

[[Ibn al-Nafis]] described metabolism in his 1260 AD work titled [[Al-Risalah al-Kamiliyyah fil Siera al-Nabawiyyah]] (The Treatise of Kamil on the Prophet's Biography) which included the following phrase "Both the body and its parts are in a continuous state of dissolution and nourishment, so they are inevitably undergoing permanent change."

[[Ibn al-Nafis]] described metabolism in his 1260 AD work titled [[Al-Risalah al-Kamiliyyah fil Siera al-Nabawiyyah]] (The Treatise of Kamil on the Prophet's Biography) which included the following phrase "Both the body and its parts are in a continuous state of dissolution and nourishment, so they are inevitably undergoing permanent change."

伊本·纳菲斯 Ibn al-Nafis 在其公元1260年的著作《 Al-Risalah al-Kamiliyyah fil Siera al-Nabawiyyah 》(《卡米尔关于先知传记的论述》)中描述了新陈代谢，其中包括以下短语: ”身体及其部分处于持续的溶解和营养状态，因此它们不可避免地要经历永久性的变化<ref>{{cite conference | vauthors = Al-Roubi AS | date = 1982 | title = Ibn Al-Nafis as a philosopher | conference = Symposium on Ibn al-Nafis, Second International Conference on Islamic Medicine | publisher = Islamic Medical Organization | location = Kuwait }} (cf. Ibn al-Nafis As a Philosopher, Encyclopedia of Islamic World [1])</ref>。

伊本·纳菲斯 Ibn al-Nafis 在其公元1260年的著作《 Al-Risalah al-Kamiliyyah fil Siera al-Nabawiyyah 》(《卡米尔关于先知传记的论述》)中描述了新陈代谢，其中包括以下短语: ”身体及其部分处于持续的溶解和营养状态，因此它们不可避免地要经历永久性的变化<ref>{{cite conference | vauthors = Al-Roubi AS | date = 1982 | title = Ibn Al-Nafis as a philosopher | conference = Symposium on Ibn al-Nafis, Second International Conference on Islamic Medicine | publisher = Islamic Medical Organization | location = Kuwait }} (cf. Ibn al-Nafis As a Philosopher, Encyclopedia of Islamic World [1])</ref>。

===Application of the scientific method===

===科学方法的应用 ===

The history of the scientific study of metabolism spans several centuries and has moved from examining whole animals in early studies, to examining individual metabolic reactions in modern biochemistry.  The first controlled [[experiment]]s in human metabolism were published by [[Santorio Santorio]] in 1614 in his book ''Ars de statica medicina''. He described how he weighed himself before and after eating, [[sleeping|sleep]], working, sex, fasting, drinking, and excreting. He found that most of the food he took in was lost through what he called "[[insensible perspiration]]".

The history of the scientific study of metabolism spans several centuries and has moved from examining whole animals in early studies, to examining individual metabolic reactions in modern biochemistry.  The first controlled [[experiment]]s in human metabolism were published by [[Santorio Santorio]] in 1614 in his book ''Ars de statica medicina''. He described how he weighed himself before and after eating, [[sleeping|sleep]], working, sex, fasting, drinking, and excreting. He found that most of the food he took in was lost through what he called "[[insensible perspiration]]".

* [http://www.sciencegateway.org/resources/biologytext/index.html MIT Biology Hypertextbook] Undergraduate-level guide to molecular biology.

* [http://www.sciencegateway.org/resources/biologytext/index.html MIT Biology Hypertextbook] Undergraduate-level guide to molecular biology.

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title = 与新陈代谢有关的文章