《生物化学—代谢篇》第十九章 代谢

Biochemistry‖l -Metabolism: The degradation and synthesis of biomolecules

Biochemistry II --Metabolism: The degradation and synthesis of biomolecules

Chapter 19 An Overview of metabolism

Chapter 19 An Overview of Metabolism

代谢的定义 生物代谢是指生物活体与外界环境不断进行的物 质(包括气体、液体和固体)交换过程。 ·合成代谢一般是指将简单的小分子物质转变成复 杂的大分子物质的过程。分解代谢则是将复杂的 大分子物质转变成小分子物质的过程。 糖、脂和蛋白质的合成代谢途径各不相同,但是 它们的分解代谢途径则有共同之处,即糖、脂和 蛋白质经过一系列分解反应后都生成了酮酸并进 入三羧酸循环,最后被氧化成CO2和H2O

代谢的定义 • 生物代谢是指生物活体与外界环境不断进行的物 质（包括气体、液体和固体）交换过程。 • 合成代谢一般是指将简单的小分子物质转变成复 杂的大分子物质的过程。分解代谢则是将复杂的 大分子物质转变成小分子物质的过程。 • 糖、脂和蛋白质的合成代谢途径各不相同，但是 它们的分解代谢途径则有共同之处，即糖、脂和 蛋白质经过一系列分解反应后都生成了酮酸并进 入三羧酸循环，最后被氧化成CO2和H2O

新陈代谢的类型 合成代谢「由小分子合成大分子 同化作用)需要能量 新陈代谢 分解代谢将大分子分解成小分子 (异化作用)释放能量

◆ ◆新陈代谢的类型： 新陈代谢 合成代谢 （同化作用） 分解代谢 （异化作用） 由小分子合成大分子 需要能量 将大分子分解成小分子 释放能量

1. The roles of metabolism Metabolism is a highly coordinated and directed cell activity in which many multienzyme systems cooperate to accomplish four functions O to obtain chemical energy by capturing solar energy or by degrading energy-rich nutrients from the environment (2)to convert nutrient molecules into the cells own characteristic molecules, including macromolecular precursors, (3)to polymerize monomeric precursors into proteins nucleic acids, lipids, polysaccharides, and other cell components; (4) to synthesize and degrade biomolecules required in specialized cellular functions

1. The Roles of metabolism Metabolism is a highly coordinated and directed cell activity, in which many multienzyme systems cooperate to accomplish four functions: (l) to obtain chemical energy by capturing solar energy or by degrading energy-rich nutrients from the environment; (2) to convert nutrient molecules into the cell's own characteristic molecules, including macromolecular precursors; (3) to polymerize monomeric precursors into proteins, nucleic acids, lipids, polysaccharides, and other cell components; (4) to synthesize and degrade biomolecules required in specialized cellular functions

Energy-yielding Cell nutrients macromolecules Carbohydrates Proteins Fats Polysaccharides Proteins Lipids Nucleic acids The energy supply ADP HPOZ NAD and demand in NADP Catabolism Anabolism Heterotrophs ATP NADH NADPH the ATP-ADP Chemical energy Cyc cle Energy.poor Precursor end products molecules Amino acids Sugars Fatty acids Nitrogenous ase

The energy supply and demand in Heterotrophs: the ATP-ADP cycle

2 The General features of metabolism Occurs in linear, branched or circular pathways Highly interconnected ( Every road leads to Rome" ). Highly regulated to achieve the best economy C Balanced supply and demand) The number of reactions is largeover 1000) and the number of types of reactions is relatively smal.(见课本p5-15) Well conserved during evolution: reflecting the unity of the life phenomena( what happens in bacteria happens in human being)

2. The General Features of metabolism • Occurs in linear, branched or circular pathways; • Highly interconnected (“Every road leads to Rome”). • Highly regulated to achieve the best economy (“Balanced supply and demand”). • The number of reactions is large (over 1000) and the number of types of reactions is relatively small.（见课本p5~15） • Well conserved during evolution: reflecting the unity of the life phenomena (“what happens in bacteria happens in human being”)

Degradation is convergent Rubber carotenoid and energy releasing pigment Phospholipid 异戊烯磷酸mn Cholester Triacylglycerols Fatty acids Mevalonate Vitamin K Cholestan tarch Alanine heyl 乙酰辅酶A alanine Acetate Glycogen Glucose rural facetyI-CoA) Acetoacetvl-CoA Eicosanoids Serine Isoleucine Fatty acids Triacylglycerols Citrate 柠檬酸 CDP-diglyceride 草酰乙酸octe The citric (b) acid cycle Synthesis is divergent and energy consuming

Degradation is convergent and energy releasing Synthesis is divergent and energy consuming The citric acid cycle 乙酰辅酶A 草酰乙酸 柠檬酸 异戊烯焦磷酸

3. Things that will be covered 1). General principles for bioenergetics 2). Oxidative degradation of fuels (glycolysis, B oxidation urea cycle, a-ketoacid oxidation citric acid cycle), generating NADH, FADH2, ATP, and CO2 3). Oxidation of NADH and FADH2 by o2 and generation of ATP and H2o (respiratory chains, ATP synthase) 4). Photosynthsis(photophosphorylation and carbon fixation) 5). Regulation of metabolism

3. Things that will be covered • 1). General principles for bioenergetics. 2). Oxidative degradation of fuels (glycolysis, b￾oxidation, urea cycle, a-ketoacid oxidation, citric acid cycle), generating NADH, FADH2 , ATP, and CO2 . 3). Oxidation of NADH and FADH2 by O2 and generation of ATP and H2O (respiratory chains, ATP synthase). 4). Photosynthsis (photophosphorylation and carbon fixation). 5). Regulation of metabolism

4. Understanding Metabolism: a retrospect

4. Understanding Metabolism: a retrospect