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This is a diagram depicting a large set of human metabolic pathways.

This is a diagram depicting a large set of human metabolic pathways.

Most of the structures that make up animals, plants and microbes are made from four basic classes of [[molecule]]: [[amino acid]]s, [[carbohydrate]]s , [[nucleic acid]] and [[lipid]]s (often called [[fat]]s). As these molecules are vital for life, metabolic reactions either focus on making these molecules during the construction of cells and tissues, or by breaking them down and using them as a source of energy, by their digestion. These biochemicals can be joined together to make [[polymer]]s such as [[DNA]] and [[protein]]s, essential [[macromolecules]] of life.<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>

Most of the structures that make up animals, plants and microbes are made from four basic classes of [[molecule]]: [[amino acid]]s, [[carbohydrate]]s , [[nucleic acid]] and [[lipid]]s (often called [[fat]]s). As these molecules are vital for life, metabolic reactions either focus on making these molecules during the construction of cells and tissues, or by breaking them down and using them as a source of energy, by their digestion. These biochemicals can be joined together to make [[polymer]]s such as [[DNA]] and [[protein]]s, essential [[macromolecules]] of life.<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>

Most of the structures that make up animals, plants and microbes are made from four basic classes of molecule: amino acids, carbohydrates , nucleic acid and lipids (often called fats). As these molecules are vital for life, metabolic reactions either focus on making these molecules during the construction of cells and tissues, or by breaking them down and using them as a source of energy, by their digestion. These biochemicals can be joined together to make polymers such as DNA and proteins, essential macromolecules of life.

Most of the structures that make up animals, plants and microbes are made from four basic classes of molecule: amino acids, carbohydrates , nucleic acid and lipids (often called fats). As these molecules are vital for life, metabolic reactions either focus on making these molecules during the construction of cells and tissues, or by breaking them down and using them as a source of energy, by their digestion. These biochemicals can be joined together to make polymers such as DNA and proteins, essential macromolecules of life.

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，要么通过消化分解这些分子并将其作为能量来源。这些生化物质可以结合在一起形成聚合物，如 DNA 和蛋白质，这些都是生命必不可少的’’’<font color=’’#ff8000’’> 大分子聚合物macromolecules</font>’’’。

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’’’<font color=’’#ff8000’’> 大分子聚合物macromolecules</font>’’’。

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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，通过’’’<font color=’’#ff8000’’>肽键 peptide bonds</font>’’’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’’’<font color=’’#ff8000’’> 细胞骨架cytoskeleton</font>’’’的蛋白质，细胞骨架是维持细胞形状的支架系统。蛋白质在’’’<font color=’’#ff8000’’>细胞信号传导 cell signaling</font>’’’、’’’<font color=’’#ff8000’’> 免疫反应immune responses</font>’’’、’’’<font color=’’#ff8000’’> 细胞粘附cell adhesion</font>’’’、主动跨膜转运和’’’<font color=’’#ff8000’’>细胞周期 cell cycle</font>’’’中也很重要。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，尤其是在’’’<font color=’’#ff8000’’>葡萄糖 glucose</font>’’’等主要能量来源匮乏或细胞发生代谢应激时。

蛋白质是由氨基酸组成的线性链，它们通过’’’<font color=’’#ff8000’’>肽键 peptide bonds</font>’’’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’’’<font color=’’#ff8000’’> 细胞骨架cytoskeleton</font>’’’的蛋白质（细胞骨架是维持细胞形状的支架系统）。蛋白质在’’’<font color=’’#ff8000’’>细胞信号传导 cell signaling</font>’’’、’’’<font color=’’#ff8000’’> 免疫反应immune responses</font>’’’、’’’<font color=’’#ff8000’’> 细胞粘附cell adhesion</font>’’’、主动跨膜转运和’’’<font color=’’#ff8000’’>细胞周期 cell cycle</font>’’’中也很重要。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，尤其是在’’’<font color=’’#ff8000’’>葡萄糖 glucose</font>’’’等主要能量来源匮乏或细胞发生代谢应激时。

Lipids are the most diverse group of biochemicals. Their main structural uses are as part of biological membranes both internal and external, such as the cell membrane, or as a source of energy. Lipids are usually defined as hydrophobic or amphipathic biological molecules but will dissolve in organic solvents such as alcohol, benzene or chloroform. The fats are a large group of compounds that contain fatty acids and glycerol; a glycerol molecule attached to three fatty acid esters is called a triacylglyceride. Several variations on this basic structure exist, including backbones such as sphingosine in the sphingomyelin, and hydrophilic groups such as phosphate as in phospholipids. Steroids such as sterol are another major class of lipids.

Lipids are the most diverse group of biochemicals. Their main structural uses are as part of biological membranes both internal and external, such as the cell membrane, or as a source of energy. Lipids are usually defined as hydrophobic or amphipathic biological molecules but will dissolve in organic solvents such as alcohol, benzene or chloroform. The fats are a large group of compounds that contain fatty acids and glycerol; a glycerol molecule attached to three fatty acid esters is called a triacylglyceride. Several variations on this basic structure exist, including backbones such as sphingosine in the sphingomyelin, and hydrophilic groups such as phosphate as in phospholipids. Steroids such as sterol are another major class of lipids.

脂类是最多样化的生物化学物质。它们的主要结构用途是作为’’’<font color=’’#ff8000’’> 生物膜biological membranes</font>’’’的内部和外部的一部分，如’’’<font color=’’#ff8000’’> 细胞膜cell membrane</font>’’’，或作为能量来源。脂类通常被定义为疏水性或两亲性的生物分子，但会溶解在有机溶剂中，如酒精、苯或氯仿。脂肪是一大类含有脂肪酸和甘油的化合物，一个甘油分子连接到三个脂肪酸酯称为三酰甘油酯。这种基本结构存在一些变异，包括主骨(如鞘氨醇)和亲水基(如磷脂中的磷酸盐)。’’’<font color=’’#ff8000’’> 类固醇Steroids</font>’’’，如’’’<font color=’’#ff8000’’>固醇sterol </font>’’’，是另一类主要的脂类。

脂类是最多样化的生物化学物质。它们的主要结构用途是作为’’’<font color=’’#ff8000’’> 生物膜biological membranes</font>’’’内部和外部的一部分，如’’’<font color=’’#ff8000’’> 细胞膜cell membrane</font>’’’，或作为能量来源。脂类通常被定义为疏水性或两亲性的生物分子，但会溶解在有机溶剂中，如酒精、苯或氯仿。脂肪是一大类含有脂肪酸和甘油的化合物，一个甘油分子连接到三个脂肪酸酯即称为三酰甘油酯。这种基本结构存在一些变异，包括主骨(如鞘磷脂中到鞘氨醇)和亲水基(如磷脂中的磷酸盐)。’’’<font color=’’#ff8000’’> 类固醇Steroids</font>’’’，如’’’<font color=’’#ff8000’’>固醇sterol </font>’’’，是另一类主要的脂类。

Carbohydrates are aldehydes or ketones, 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 monosaccharides and include galactose, fructose, and most importantly glucose. Monosaccharides can be linked together to form polysaccharides in almost limitless ways.

Carbohydrates are aldehydes or ketones, 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 monosaccharides and include galactose, fructose, and most importantly glucose. Monosaccharides can be linked together to form polysaccharides in almost limitless ways.

The two nucleic acids, DNA and RNA, are polymers of nucleotides. 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 and protein biosynthesis.This information is protected by DNA repair mechanisms and propagated through DNA replication. Many viruses have an RNA genome, such as HIV, which uses reverse transcription to create a DNA template from its viral RNA genome.RNA in ribozymes such as spliceosomes and ribosomes is similar to enzymes as it can catalyze chemical reactions. Individual nucleosides are made by attaching a nucleobase to a ribose sugar. These bases are heterocyclic rings containing nitrogen, classified as purines or pyrimidines. Nucleotides also act as coenzymes in metabolic-group-transfer reactions.

The two nucleic acids, DNA and RNA, are polymers of nucleotides. 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 and protein biosynthesis.This information is protected by DNA repair mechanisms and propagated through DNA replication. Many viruses have an RNA genome, such as HIV, which uses reverse transcription to create a DNA template from its viral RNA genome.RNA in ribozymes such as spliceosomes and ribosomes is similar to enzymes as it can catalyze chemical reactions. Individual nucleosides are made by attaching a nucleobase to a ribose sugar. These bases are heterocyclic rings containing nitrogen, classified as purines or pyrimidines. Nucleotides also act as coenzymes in metabolic-group-transfer reactions.

DNA和RNA这两种核酸是核苷酸的聚合物。每个核苷酸都是由一个磷酸连接到核糖或脱氧核糖糖基上，而核糖或脱氧核糖糖基又连接到含氮碱基上。核酸对于遗传信息的储存和使用，以及通过转录和蛋白质生物合成过程对其进行解释至关重要，这些信息受到DNA修复机制的保护，并通过DNA复制进行传播。许多病毒都有RNA基因组，如HIV病毒，它利用’’’<font color=’’#ff8000’’> 逆转录reverse transcription</font>’’’从其病毒RNA基因组中创建DNA模板，核糖体和核糖体等核糖体中的RNA类似于酶，因为它可以催化化学反应。单个核苷是通过将核碱基连接到核糖上制成的。这些碱基是含氮的杂环，分为嘌呤或嘧啶。核苷酸还在代谢基团转移反应中充当辅酶。

DNA和RNA这两种核酸是核苷酸的聚合物。每个核苷酸都是由一个磷酸连接到核糖或脱氧核糖糖基上形成的，而核糖或脱氧核糖糖基又连接到含氮碱基上。核酸对于遗传信息的储存和使用，以及通过转录和蛋白质生物合成过程对其进行解释至关重要。这些信息受到DNA修复机制的保护，并通过DNA复制进行传播。许多病毒都有RNA基因组，如HIV病毒，它利用’’’<font color=’’#ff8000’’> 逆转录reverse transcription</font>’’’从其病毒RNA基因组中创建DNA模板。核糖体和核糖体等核糖体中的RNA类似于酶，因为它可以催化化学反应。单个核苷是通过将核碱基连接到核糖上制成的。这些碱基是含氮的杂环，分为嘌呤或嘧啶。核苷酸还在代谢基团转移反应中充当辅酶。

Structure of the [[coenzyme acetyl-CoA.The transferable acetyl group is bonded to the sulfur atom at the extreme left.]]

Structure of the [[coenzyme acetyl-CoA.The transferable acetyl group is bonded to the sulfur atom at the extreme left.]]

[[辅酶乙酰辅酶 a。可转移的乙酰基与最左边的硫原子成键结合。]]

[[辅酶乙酰辅酶结构 a。可转移的乙酰基与最左边的硫原子成键结合。]]

{{main|Coenzyme}}

{{main|Coenzyme}}

Metabolism involves a vast array of chemical reactions, but most fall under a few basic types of reactions that involve the transfer of functional groups of atoms and their bonds within molecules. This common chemistry allows cells to use a small set of metabolic intermediates to carry chemical groups between different reactions. These group-transfer intermediates are called coenzymes. Each class of group-transfer reactions is carried out by a particular coenzyme, which is the substrate for a set of enzymes that produce it, and a set of enzymes that consume it. These coenzymes are therefore continuously made, consumed and then recycled.

Metabolism involves a vast array of chemical reactions, but most fall under a few basic types of reactions that involve the transfer of functional groups of atoms and their bonds within molecules. This common chemistry allows cells to use a small set of metabolic intermediates to carry chemical groups between different reactions. These group-transfer intermediates are called coenzymes. Each class of group-transfer reactions is carried out by a particular coenzyme, which is the substrate for a set of enzymes that produce it, and a set of enzymes that consume it. These coenzymes are therefore continuously made, consumed and then recycled.

One central coenzyme is adenosine triphosphate (ATP), the universal energy currency of cells. This nucleotide is used to transfer chemical energy between different chemical reactions. There is only a small amount of ATP in cells, but as it is continuously regenerated, the human body can use about its own weight in ATP per day. ATP acts as a bridge between catabolism and anabolism. Catabolism breaks down molecules, and anabolism puts them together. Catabolic reactions generate ATP, and anabolic reactions consume it. It also serves as a carrier of phosphate groups in phosphorylation reactions.

One central coenzyme is adenosine triphosphate (ATP), the universal energy currency of cells. This nucleotide is used to transfer chemical energy between different chemical reactions. There is only a small amount of ATP in cells, but as it is continuously regenerated, the human body can use about its own weight in ATP per day. ATP acts as a bridge between catabolism and anabolism. Catabolism breaks down molecules, and anabolism puts them together. Catabolic reactions generate ATP, and anabolic reactions consume it. It also serves as a carrier of phosphate groups in phosphorylation reactions.

A vitamin is an organic compound needed in small quantities that cannot be made in cells. In human nutrition, most vitamins function as coenzymes after modification; for example, all water-soluble vitamins are phosphorylated or are coupled to nucleotides when they are used in cells. Nicotinamide adenine dinucleotide (NAD⁺), a derivative of vitamin B₃ (niacin), is an important coenzyme that acts as a hydrogen acceptor. Hundreds of separate types of dehydrogenases remove electrons from their substrates and reduce NAD⁺ into NADH. This reduced form of the coenzyme is then a substrate for any of the reductases in the cell that need to reduce their substrates. Nicotinamide adenine dinucleotide exists in two related forms in the cell, NADH and NADPH. The NAD⁺/NADH form is more important in catabolic reactions, while NADP⁺/NADPH is used in anabolic reactions.

A vitamin is an organic compound needed in small quantities that cannot be made in cells. In human nutrition, most vitamins function as coenzymes after modification; for example, all water-soluble vitamins are phosphorylated or are coupled to nucleotides when they are used in cells. Nicotinamide adenine dinucleotide (NAD⁺), a derivative of vitamin B₃ (niacin), is an important coenzyme that acts as a hydrogen acceptor. Hundreds of separate types of dehydrogenases remove electrons from their substrates and reduce NAD⁺ into NADH. This reduced form of the coenzyme is then a substrate for any of the reductases in the cell that need to reduce their substrates. Nicotinamide adenine dinucleotide exists in two related forms in the cell, NADH and NADPH. The NAD⁺/NADH form is more important in catabolic reactions, while NADP⁺/NADPH is used in anabolic reactions.

’’’<font color=’’#ff8000’’>维生素 vitamin </font>’’’是一种细胞不能合成的少量需要的有机化合物。在人体营养中，大多数维生素经过修饰后都具有辅酶的功能，例如，所有水溶性维生素在细胞中使用时都会被磷酸化或与核苷酸偶联。’’’<font color=’’#ff8000’’>烟酰胺腺嘌呤二核苷酸 Nicotinamide adenine dinucleotide</font>’’’(NAD⁺)是维生素B₃(烟酸)的衍生物，是一种重要的辅酶，起着氢接受器的作用。数百种不同类型的脱氢酶从其底物中去除电子，并将NAD<sub>+</sup>还原成NADH。这种还原形式的辅酶是细胞中任何需要还原其底物的还原酶的底物。烟酰胺腺嘌呤二核苷酸在细胞中以两种相关形式存在，即NADH和NADPH。NAD < sup > + </sup >/NADH 形式在分解代谢反应中起重要作用，而 NADP < sup > + </sup >/NADPH 形式在分解代谢反应中起重要作用。

’’’<font color=’’#ff8000’’>维生素 vitamin </font>’’’是一类细胞不能合成的微量有机化合物。在人体营养中，大多数维生素经过修饰后都具有辅酶的功能，例如，所有水溶性维生素在细胞中使用时都会被磷酸化或与核苷酸偶联。’’’<font color=’’#ff8000’’>烟酰胺腺嘌呤二核苷酸 Nicotinamide adenine dinucleotide</font>’’’(NAD⁺)是维生素B₃(烟酸)的衍生物，它是一种重要的辅酶，起着氢接受器的作用。数百种不同类型的脱氢酶从其底物中去除电子，并将NAD<sub>+</sup>还原成NADH。这种还原形式的辅酶是细胞中任何需要还原其底物的还原酶的底物。烟酰胺腺嘌呤二核苷酸在细胞中以两种相关形式存在，即NADH和NADPH。NAD < sup > + </sup >/NADH 形式在分解代谢反应中起重要作用，而 NADP < sup > + </sup >/NADPH 形式在分解代谢反应中起重要作用。

The abundant inorganic elements act as electrolytes. The most important ions are sodium, potassium, calcium, magnesium, chloride, phosphate and the organic ion bicarbonate. The maintenance of precise ion gradients across cell membranes maintains osmotic pressure and pH. Ions are also critical for nerve and muscle function, as action potentials in these tissues are produced by the exchange of electrolytes between the extracellular fluid and the cell's fluid, the cytosol. Electrolytes enter and leave cells through proteins in the cell membrane called ion channels. For example, muscle contraction depends upon the movement of calcium, sodium and potassium through ion channels in the cell membrane and T-tubules.

The abundant inorganic elements act as electrolytes. The most important ions are sodium, potassium, calcium, magnesium, chloride, phosphate and the organic ion bicarbonate. The maintenance of precise ion gradients across cell membranes maintains osmotic pressure and pH. Ions are also critical for nerve and muscle function, as action potentials in these tissues are produced by the exchange of electrolytes between the extracellular fluid and the cell's fluid, the cytosol. Electrolytes enter and leave cells through proteins in the cell membrane called ion channels. For example, muscle contraction depends upon the movement of calcium, sodium and potassium through ion channels in the cell membrane and T-tubules.

丰富的无机元素充当电解质。最重要的离子是钠、钾、钙、镁、氯化物、磷酸盐和有机离子重碳酸盐。维持细胞膜上精确的离子梯度可以维持’’’<font color=’’#ff8000’’>渗透压 osmotic pressure</font>’’’和 ph 值。离子对于神经和肌肉功能也是至关重要的，因为这些组织的动作电位是由细胞外液和细胞液（细胞液）之间的电解质交换产生的。电解质通过细胞膜上称为离子通道的蛋白质进入和离开细胞。例如，肌肉收缩依赖于钙、钠和钾通过细胞膜和T管中的离子通道的运动。

丰富的无机元用作电解质。最重要的离子是钠、钾、钙、镁、氯化物、磷酸盐和有机离子重碳酸盐。维持细胞膜上精确的离子梯度可以维持’’’<font color=’’#ff8000’’>渗透压 osmotic pressure</font>’’’和 ph 值。离子对于神经和肌肉功能也是至关重要的，因为这些组织中的动作电位是由细胞外液和细胞液之间的电解质交换产生的。电解质通过细胞膜上称为离子通道的蛋白质进入和离开细胞。例如，肌肉收缩依赖于钙、钠和钾通过细胞膜和T管中的离子通道的运动。

[[Transition metal]]s are usually present as [[trace element]]s in organisms, with [[zinc]] and [[iron]] being most abundant of those.<ref>{{cite book| vauthors = Torres-Romero JC, Alvarez-Sánchez ME, Fernández-Martín K, Alvarez-Sánchez LC, Arana-Argáez V, Ramírez-Camacho M, Lara-Riegos J | chapter=Zinc Efflux in Trichomonas vaginalis: In Silico Identification and Expression Analysis of CDF-Like Genes|date=2018| title =Quantitative Models for Microscopic to Macroscopic Biological Macromolecules and Tissues|pages=149–168| veditors = Olivares-Quiroz L, Resendis-Antonio O |place=Cham|publisher=Springer International Publishing|language=en|doi=10.1007/978-3-319-73975-5_8|isbn=978-3-319-73975-5 }}</ref> These metals are used in some proteins as [[Cofactor (biochemistry)|cofactors]] and are essential for the activity of enzymes such as [[catalase]] and oxygen-carrier proteins such as [[hemoglobin]]<ref>{{cite book|last=Craig Will|first=Leonard Ashley | name-list-style = vanc |title=Manufacturing Engineering & Technology|publisher=Scientific e-Resources|year=2019|isbn=9781839472428|location=Waltham Abbey|pages=190–196}}</ref> Metal cofactors are bound tightly to specific sites in proteins; although enzyme cofactors can be modified during catalysis, they always return to their original state by the end of the reaction catalyzed. Metal micronutrients are taken up into organisms by specific transporters and bind to storage proteins such as [[ferritin]] or [[metallothionein]] when not in use.<ref>{{cite journal | vauthors = Cousins RJ, Liuzzi JP, Lichten LA | title = Mammalian zinc transport, trafficking, and signals | journal = The Journal of Biological Chemistry | volume = 281 | issue = 34 | pages = 24085–9 | date = August 2006 | pmid = 16793761 | doi = 10.1074/jbc.R600011200 | url = https://www.jbc.org/content/281/34/24085 | doi-access = free }}</ref><ref>{{cite journal | vauthors = Dunn LL, Suryo Rahmanto Y, Richardson DR | title = Iron uptake and metabolism in the new millennium | journal = Trends in Cell Biology | volume = 17 | issue = 2 | pages = 93–100 | date = February 2007 | pmid = 17194590 | doi = 10.1016/j.tcb.2006.12.003 }}</ref>

[[Transition metal]]s are usually present as [[trace element]]s in organisms, with [[zinc]] and [[iron]] being most abundant of those.<ref>{{cite book| vauthors = Torres-Romero JC, Alvarez-Sánchez ME, Fernández-Martín K, Alvarez-Sánchez LC, Arana-Argáez V, Ramírez-Camacho M, Lara-Riegos J | chapter=Zinc Efflux in Trichomonas vaginalis: In Silico Identification and Expression Analysis of CDF-Like Genes|date=2018| title =Quantitative Models for Microscopic to Macroscopic Biological Macromolecules and Tissues|pages=149–168| veditors = Olivares-Quiroz L, Resendis-Antonio O |place=Cham|publisher=Springer International Publishing|language=en|doi=10.1007/978-3-319-73975-5_8|isbn=978-3-319-73975-5 }}</ref> These metals are used in some proteins as [[Cofactor (biochemistry)|cofactors]] and are essential for the activity of enzymes such as [[catalase]] and oxygen-carrier proteins such as [[hemoglobin]]<ref>{{cite book|last=Craig Will|first=Leonard Ashley | name-list-style = vanc |title=Manufacturing Engineering & Technology|publisher=Scientific e-Resources|year=2019|isbn=9781839472428|location=Waltham Abbey|pages=190–196}}</ref> Metal cofactors are bound tightly to specific sites in proteins; although enzyme cofactors can be modified during catalysis, they always return to their original state by the end of the reaction catalyzed. Metal micronutrients are taken up into organisms by specific transporters and bind to storage proteins such as [[ferritin]] or [[metallothionein]] when not in use.<ref>{{cite journal | vauthors = Cousins RJ, Liuzzi JP, Lichten LA | title = Mammalian zinc transport, trafficking, and signals | journal = The Journal of Biological Chemistry | volume = 281 | issue = 34 | pages = 24085–9 | date = August 2006 | pmid = 16793761 | doi = 10.1074/jbc.R600011200 | url = https://www.jbc.org/content/281/34/24085 | doi-access = free }}</ref><ref>{{cite journal | vauthors = Dunn LL, Suryo Rahmanto Y, Richardson DR | title = Iron uptake and metabolism in the new millennium | journal = Trends in Cell Biology | volume = 17 | issue = 2 | pages = 93–100 | date = February 2007 | pmid = 17194590 | doi = 10.1016/j.tcb.2006.12.003 }}</ref>

Transition metals are usually present as trace elements in organisms, with zinc and iron being most abundant of those. These metals are used in some proteins as cofactors and are essential for the activity of enzymes such as catalase and oxygen-carrier proteins such as hemoglobin Metal cofactors are bound tightly to specific sites in proteins; although enzyme cofactors can be modified during catalysis, they always return to their original state by the end of the reaction catalyzed. Metal micronutrients are taken up into organisms by specific transporters and bind to storage proteins such as ferritin or metallothionein when not in use.

Transition metals are usually present as trace elements in organisms, with zinc and iron being most abundant of those. These metals are used in some proteins as cofactors and are essential for the activity of enzymes such as catalase and oxygen-carrier proteins such as hemoglobin. Metal cofactors are bound tightly to specific sites in proteins; although enzyme cofactors can be modified during catalysis, they always return to their original state by the end of the reaction catalyzed. Metal micronutrients are taken up into organisms by specific transporters and bind to storage proteins such as ferritin or metallothionein when not in use.

过渡金属通常以微量元素的形式存在于生物体内，其中锌和铁最为丰富。这些金属元素在某些蛋白质中作为辅因子，是催化酶等酶和血红蛋白等氧载体蛋白活性所必需的金属辅因子。金属辅因子与蛋白质中的特定位点紧密结合，虽然在催化过程中酶的辅因子可以被改变，但在催化反应结束时，它们总是恢复到原来的状态。金属微量营养素由特定的转运体带入生物体内，不用时与储存蛋白如铁蛋白或金属硫蛋白结合。

过渡金属通常以微量元素的形式存在于生物体内，其中锌和铁最为丰富。这些金属元素在某些蛋白质中作为辅因子，是催化酶等酶和血红蛋白等氧载体蛋白活性所必需的金属辅因子。金属辅因子与蛋白质中的特定位点紧密结合，虽然在催化过程中酶的辅因子可以被改变，但在催化反应结束时，它们总是恢复到原来的状态。金属微量营养素由特定的转运体带入生物体内，不用时与储存蛋白如铁蛋白或金属硫蛋白结合。

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 organotrophs, while lithotrophs use inorganic substrates, and phototrophs capture sunlight as 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 molecules, water, ammonia, hydrogen sulfide or ferrous ions to acceptor molecules such as oxygen, nitrate or sulfate. In animals, these reactions involve complex organic molecules that are broken down to simpler molecules, such as carbon dioxide and water. In 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 organotrophs, while lithotrophs use inorganic substrates, and phototrophs capture sunlight as 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 molecules, water, ammonia, hydrogen sulfide or ferrous ions to acceptor molecules such as oxygen, nitrate or sulfate. In animals, these reactions involve complex organic molecules that are broken down to simpler molecules, such as carbon dioxide and water. In 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.

The most common set of catabolic reactions in animals can be separated into three main stages. In the first stage, large organic molecules, such as proteins, polysaccharides or lipids, are digested into their smaller components outside cells. Next, these smaller molecules are taken up by cells and converted to smaller molecules, usually acetyl coenzyme A (acetyl-CoA), which releases some energy. Finally, the acetyl group on the CoA is oxidised to water and carbon dioxide in the citric acid cycle and electron transport chain, releasing the energy that is stored by reducing the coenzyme nicotinamide adenine dinucleotide (NAD⁺) into NADH.

The most common set of catabolic reactions in animals can be separated into three main stages. In the first stage, large organic molecules, such as proteins, polysaccharides or lipids, are digested into their smaller components outside cells. Next, these smaller molecules are taken up by cells and converted to smaller molecules, usually acetyl coenzyme A (acetyl-CoA), which releases some energy. Finally, the acetyl group on the CoA is oxidised to water and carbon dioxide in the citric acid cycle and electron transport chain, releasing the energy that is stored by reducing the coenzyme nicotinamide adenine dinucleotide (NAD⁺) into NADH.

动物中最常见的分解代谢反应可以分为三个主要阶段。在第一阶段，大的有机分子，如蛋白质，多糖或脂类，在细胞外被消化成较小的成分。接下来，这些较小的分子被细胞吸收并转化成小分子，通常是乙酰辅酶A (acetyl-CoA) ，释放出一些能量。最后，辅酶 a 上的乙酰基被氧化成三羧酸循环和电子传递链中的水和二氧化碳，释放出储存的能量，将辅酶烟酰胺腺嘌呤二核苷酸（NAD⁺）还原成NADH。

动物中最常见的分解代谢反应可以分为三个主要阶段。在第一阶段，大的有机分子，如蛋白质，多糖或脂类，在细胞外被消化成较小的分子。接下来，这些较小的分子被细胞吸收并转化成更小的分子，通常是乙酰辅酶A (acetyl-CoA) ，并释放出一些能量。最后，辅酶 A 上的乙酰基在三羧酸循环和电子传递链中被氧化成水和二氧化碳，释放出储存的能量，将辅酶烟酰胺腺嘌呤二核苷酸（NAD⁺）还原成NADH。

Microbes simply secrete digestive enzymes into their surroundings, while animals only secrete these enzymes from specialized cells in their guts, including the stomach and pancreas, and salivary glands. The amino acids or sugars released by these extracellular enzymes are then pumped into cells by active transport proteins.

Microbes simply secrete digestive enzymes into their surroundings, while animals only secrete these enzymes from specialized cells in their guts, including the stomach and pancreas, and salivary glands. The amino acids or sugars released by these extracellular enzymes are then pumped into cells by active transport proteins.

微生物只是简单地将消化酶分泌到周围环境中，而动物只是从它们肠道(包括胃、胰腺和唾液腺)中的特定细胞分泌这些酶。这些细胞外酶释放的氨基酸或糖通过活性转运蛋白被泵入细胞内。

微生物简单直接地将消化酶分泌到周围环境中，而动物必须通过它们肠道(包括胃、胰腺和唾液腺)中的特定细胞分泌这些酶。这些细胞外酶释放的氨基酸或糖通过活性转运蛋白被泵入细胞内。

[[File:Catabolism schematic.svg|thumb|left|upright=1.35|A simplified outline of the catabolism of [[protein]]s, [[carbohydrate]]s and [[fat]]s]]

[[File:Catabolism schematic.svg|thumb|left|upright=1.35|A simplified outline of the catabolism of [[protein]]s, [[carbohydrate]]s and [[fat]]s]]

A simplified outline of the catabolism of [[proteins, carbohydrates and fats]]

A simplified outline of the catabolism of [[proteins, carbohydrates and fats]]

[蛋白质，碳水化合物和脂肪]分解代谢的简化概述

[蛋白质，碳水化合物和脂肪]分解代谢的简化概述  

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。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，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。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，通过乳酸脱氢酶将NADH重新氧化为NAD < sup > + </sup > 再用于糖酵解。葡萄糖分解的另一种途径是磷酸戊糖途径，它降低辅酶NADPH并产生戊糖，如核糖，核糖是核酸的糖成分。

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，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。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。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''.<ref>{{cite journal | vauthors = Wipperman MF, Sampson NS, Thomas ST | title = Pathogen roid rage: cholesterol utilization by Mycobacterium tuberculosis | journal = Critical Reviews in Biochemistry and Molecular Biology | volume = 49 | issue = 4 | pages = 269–93 | date = 2014 | pmid = 24611808 | pmc = 4255906 | doi = 10.3109/10409238.2014.895700 }}</ref>

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''.<ref>{{cite journal | vauthors = Wipperman MF, Sampson NS, Thomas ST | title = Pathogen roid rage: cholesterol utilization by Mycobacterium tuberculosis | journal = Critical Reviews in Biochemistry and Molecular Biology | volume = 49 | issue = 4 | pages = 269–93 | date = 2014 | pmid = 24611808 | pmc = 4255906 | doi = 10.3109/10409238.2014.895700 }}</ref>

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.

脂肪通过水解分解为游离脂肪酸和甘油。甘油进入糖酵解，脂肪酸被 β氧化分解，释放出乙酰辅酶 a，然后进入三羧酸循环。脂肪酸在氧化时比碳水化合物释放更多的能量，因为碳水化合物的结构中含有更多的氧。类固醇也会被一些细菌在类似于 β 氧化的过程中分解，这个分解过程会释放出大量的乙酰辅酶 a、丙酰辅酶 a 和丙酮酸的释放，这些都可以被细胞用来提供能量。结核杆菌也可以依靠脂质胆固醇作为唯一的碳源生长，而且参与胆固醇利用途径的基因已经被证实在结核杆菌感染生命周期的不同阶段都是重要的。

脂肪通过水解作用分解为游离脂肪酸和甘油。甘油进入糖酵解，脂肪酸被 β氧化分解，释放出乙酰辅酶A，然后进入三羧酸循环。脂肪酸在氧化时会释放比碳水化合物更多的能量，因为碳水化合物的结构中含有更多的氧。类固醇也会被一些细菌在类似于 β 氧化的过程中分解，这个分解过程会释放出大量的乙酰辅酶A、丙酰辅酶A和丙酮酸，它们都可以给细胞提供能量。结核杆菌也可以依靠脂质胆固醇这唯一的碳源生长，而且参与胆固醇利用途径的基因已经被证实在结核杆菌感染生命周期的不同阶段都是重要的。

[[Amino acid]]s are either used to synthesize proteins and other biomolecules, or oxidized to [[urea]] and carbon dioxide as a source of energy.<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> The oxidation pathway starts with the removal of the amino group by a [[transaminase]]. The amino group is fed into the [[urea cycle]], leaving a deaminated carbon skeleton in the form of a [[keto acid]]. Several of these keto acids are intermediates in the citric acid cycle, for example the deamination of [[glutamate]] forms α-[[alpha-Ketoglutaric acid|ketoglutarate]].<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> The [[glucogenic amino acid]]s can also be converted into glucose, through [[gluconeogenesis]] (discussed below).<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>

[[Amino acid]]s are either used to synthesize proteins and other biomolecules, or oxidized to [[urea]] and carbon dioxide as a source of energy.<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> The oxidation pathway starts with the removal of the amino group by a [[transaminase]]. The amino group is fed into the [[urea cycle]], leaving a deaminated carbon skeleton in the form of a [[keto acid]]. Several of these keto acids are intermediates in the citric acid cycle, for example the deamination of [[glutamate]] forms α-[[alpha-Ketoglutaric acid|ketoglutarate]].<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> The [[glucogenic amino acid]]s can also be converted into glucose, through [[gluconeogenesis]] (discussed below).<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>

Amino acids are either used to synthesize proteins and other biomolecules, or oxidized to urea and carbon dioxide as a source of energy. The oxidation pathway starts with the removal of the amino group by a transaminase. The amino group is fed into the urea cycle, leaving a deaminated carbon skeleton in the form of a keto acid. Several of these keto acids are intermediates in the citric acid cycle, for example the deamination of glutamate forms α-ketoglutarate. The glucogenic amino acids can also be converted into glucose, through gluconeogenesis (discussed below).

Amino acids are either used to synthesize proteins and other biomolecules, or oxidized to urea and carbon dioxide as a source of energy. The oxidation pathway starts with the removal of the amino group by a transaminase. The amino group is fed into the urea cycle, leaving a deaminated carbon skeleton in the form of a keto acid. Several of these keto acids are intermediates in the citric acid cycle, for example the deamination of glutamate forms α-ketoglutarate. The glucogenic amino acids can also be converted into glucose, through gluconeogenesis (discussed below).

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作为能量来源。氧化途径从转氨酶去除氨基开始。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。葡萄糖原氨基酸也可以通过葡萄糖异生转化为葡萄糖(下面讨论)。

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。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。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)。

In oxidative phosphorylation, the electrons removed from organic molecules in areas such as the protagon acid cycle are transferred to oxygen and the energy released is used to make ATP. This is done in eukaryotes by a series of proteins in the membranes of mitochondria called the electron transport chain. In prokaryotes, these proteins are found in the cell's inner membrane. These proteins use the energy released from passing electrons from reduced molecules like NADH onto oxygen to pump protons across a membrane.

In oxidative phosphorylation, the electrons removed from organic molecules in areas such as the protagon acid cycle are transferred to oxygen and the energy released is used to make ATP. This is done in eukaryotes by a series of proteins in the membranes of mitochondria called the electron transport chain. In prokaryotes, these proteins are found in the cell's inner membrane. These proteins use the energy released from passing electrons from reduced molecules like NADH onto oxygen to pump protons across a membrane.

在氧化磷酸化过程中，电子从有机分子中移出，例如在初磷脂酸循环的区域被转移到氧气中，释放的能量被用来制造ATP。这在真核生物中是通过线粒体膜中的一系列蛋白质来完成的，这些蛋白质被称为电子传递链。在原核生物中，这些蛋白质存在于细胞的内膜中。这些蛋白质利用电子从还原性分子(如NADH)传递到氧气所释放的能量来泵送质子穿过细胞膜。

氧化磷酸化中，通过如柠檬酸循环等代谢途径，电子从被消化吸收的食物分子上转移到氧气上，并将产生的能量以ATP的方式储存起来。在真核生物中，这一过程是通过线粒体膜上的一系列膜蛋白来完成的，被称为电子传递链。而在原核生物中，这些蛋白质存在于细胞的内膜中。这些蛋白质利用电子从还原性分子(如NADH)传递到氧气所释放的能量来泵送质子穿过细胞膜。

[[File:ATPsyn.gif|thumb|right|Mechanism of [[ATP synthase]]. ATP is shown in red, ADP and phosphate in pink and the rotating stalk subunit in black.]]

[[File:ATPsyn.gif|thumb|right|Mechanism of [[ATP synthase]]. ATP is shown in red, ADP and phosphate in pink and the rotating stalk subunit in black.]]

Pumping protons out of the mitochondria creates a proton concentration difference across the membrane and generates an electrochemical gradient. This force drives protons back into the mitochondrion through the base of an enzyme called ATP synthase. The flow of protons makes the stalk subunit rotate, causing the active site of the synthase domain to change shape and phosphorylate adenosine diphosphate– turning it into ATP.

Pumping protons out of the mitochondria creates a proton concentration difference across the membrane and generates an electrochemical gradient. This force drives protons back into the mitochondrion through the base of an enzyme called ATP synthase. The flow of protons makes the stalk subunit rotate, causing the active site of the synthase domain to change shape and phosphorylate adenosine diphosphate– turning it into ATP.

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。这种力量促使质子通过一种叫做ATP合成酶的酶的基座回到线粒体中。质子的流动使柄亚基旋转，使合成酶域的活性位点改变形状，使二磷酸腺苷磷酸化--变成ATP。

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。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。

===Energy from inorganic compounds===

===Energy from inorganic compounds===

Chemolithotrophy is a type of metabolism found in prokaryotes where energy is obtained from the oxidation of inorganic compounds. These organisms can use hydrogen, reduced sulfur compounds (such as sulfide, hydrogen sulfide and thiosulfate), or ammonia as sources of reducing power and they gain energy from the oxidation of these compounds with electron acceptors such as oxygen or nitrite. These microbial processes are important in global biogeochemical cycles such as acetogenesis, nitrification and denitrification and are critical for soil fertility.

Chemolithotrophy is a type of metabolism found in prokaryotes where energy is obtained from the oxidation of inorganic compounds. These organisms can use hydrogen, reduced sulfur compounds (such as sulfide, hydrogen sulfide and thiosulfate), or ammonia as sources of reducing power and they gain energy from the oxidation of these compounds with electron acceptors such as oxygen or nitrite. These microbial processes are important in global biogeochemical cycles such as acetogenesis, nitrification and denitrification and are critical for soil fertility.

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、还原硫化合物(如硫化物、硫化氢和硫代硫酸酯)或氨作为还原力的来源，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。这些微生物过程在全球生物地球化学循环中非常重要，如乙酰化、硝化和反硝化，对土壤肥力至关重要。

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、还原硫化合物(如硫化物、硫化氢和硫代硫酸酯)或氨作为还原力的来源，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。

===Energy from light===

===Energy from light===

The energy in sunlight is captured by plants, cyanobacteria, purple bacteria, green sulfur bacteria and some protists. This process is often coupled to the conversion of carbon dioxide into organic compounds, as part of photosynthesis, which is discussed below. The energy capture and carbon fixation systems can however operate separately in prokaryotes, as purple bacteria and green sulfur bacteria can use sunlight as a source of energy, while switching between carbon fixation and the fermentation of organic compounds.

The energy in sunlight is captured by plants, cyanobacteria, purple bacteria, green sulfur bacteria and some protists. This process is often coupled to the conversion of carbon dioxide into organic compounds, as part of photosynthesis, which is discussed below. The energy capture and carbon fixation systems can however operate separately in prokaryotes, as purple bacteria and green sulfur bacteria can use sunlight as a source of energy, while switching between carbon fixation and the fermentation of organic compounds.

In many organisms, the capture of solar energy is similar in principle to oxidative phosphorylation, as it involves the storage of energy as a proton concentration gradient. This proton motive force then drives ATP synthesis<ref>{{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 =Energy Conversion: Mitochondria and Chloroplasts|url=https://www.ncbi.nlm.nih.gov/books/NBK21063/|title =Molecular Biology of the Cell. 4th edition|language=en}}</ref> The electrons needed to drive this electron transport chain come from light-gathering proteins called [[photosynthetic reaction centre]]s. Reaction centers are classed into two types depending on the nature of [[photosynthetic pigment]] present, with most photosynthetic bacteria only having one type, while plants and cyanobacteria have two.<ref>{{cite journal | vauthors = Allen JP, Williams JC | title = Photosynthetic reaction centers | journal = FEBS Letters | volume = 438 | issue = 1–2 | pages = 5–9 | date = October 1998 | pmid = 9821949 | doi = 10.1016/S0014-5793(98)01245-9 | s2cid = 21596537 }}</ref>

In many organisms, the capture of solar energy is similar in principle to oxidative phosphorylation, as it involves the storage of energy as a proton concentration gradient. This proton motive force then drives ATP synthesis<ref>{{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 =Energy Conversion: Mitochondria and Chloroplasts|url=https://www.ncbi.nlm.nih.gov/books/NBK21063/|title =Molecular Biology of the Cell. 4th edition|language=en}}</ref> The electrons needed to drive this electron transport chain come from light-gathering proteins called [[photosynthetic reaction centre]]s. Reaction centers are classed into two types depending on the nature of [[photosynthetic pigment]] present, with most photosynthetic bacteria only having one type, while plants and cyanobacteria have two.<ref>{{cite journal | vauthors = Allen JP, Williams JC | title = Photosynthetic reaction centers | journal = FEBS Letters | volume = 438 | issue = 1–2 | pages = 5–9 | date = October 1998 | pmid = 9821949 | doi = 10.1016/S0014-5793(98)01245-9 | s2cid = 21596537 }}</ref>

In many organisms, the capture of solar energy is similar in principle to oxidative phosphorylation, as it involves the storage of energy as a proton concentration gradient. This proton motive force then drives ATP synthesis The electrons needed to drive this electron transport chain come from light-gathering proteins called photosynthetic reaction centres. Reaction centers are classed into two types depending on the nature of photosynthetic pigment present, with most photosynthetic bacteria only having one type, while plants and cyanobacteria have two.

In many organisms, the capture of solar energy is similar in principle to oxidative phosphorylation, as it involves the storage of energy as a proton concentration gradient. This proton motive force then drives ATP synthesis. The electrons needed to drive this electron transport chain come from light-gathering proteins called photosynthetic reaction centres. Reaction centers are classed into two types depending on the nature of photosynthetic pigment present, with most photosynthetic bacteria only having one type, while plants and cyanobacteria have two.

In many organisms, the capture of solar energy is similar in principle to oxidative phosphorylation, as it involves the storage of energy as a proton concentration gradient. This proton motive force then drives ATP synthesis The electrons needed to drive this electron transport chain come from light-gathering proteins called photosynthetic reaction centres. Reaction centers are classed into two types depending on the nature of photosynthetic pigment present, with most photosynthetic bacteria only having one type, while plants and cyanobacteria have two.

在许多生物体中，太阳能的获取在原理上类似于氧化磷酸化，因为它涉及到以质子浓度梯度的形式储存能量。这种质子动力驱动 ATP 的合成。驱动这种电子传递链所需的电子来自于聚光蛋白质，这种蛋白质被叫做光合反应中心。根据存在的光合色素的性质，反应中心分为两种类型。大多数光合细菌只有一种类型，而植物和蓝藻有两种类型。

 

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]].<ref name=Nelson2004/> 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^{+.<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>}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|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]].<ref name=Nelson2004/> 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^{+.<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>}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 > + </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 > + </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，释放出作为废物的氧气。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。这些质子在驱动ATP合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，然后可以被用来减少辅酶NADP< sup > + </sup >。这些库酶可用于’’’<font color=’’#ff8000’’> 卡尔文循环Calvin cycle</font>’’’(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。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 >。这些辅酶可用于’’’<font color=’’#ff8000’’> 卡尔文循环Calvin cycle</font>’’’(下文将对此进行讨论)，或被循环用于进一步生成ATP。

==Anabolism==

==Anabolism==

合成代谢

合成代谢 【Fernando标记】

{{further|Anabolism}}

{{further|Anabolism}}