文档介绍：Biochemistry II --Metabolism: The degradation and synthesis of biomolecules.
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。
◆◆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 plish 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, harides, and other ponents;
(4) to synthesize and degrade biomolecules required in specialized cellular functions.
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 (“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
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 (pho