第五节 细胞质的结构与功能 ( 二 ) The Structure and Function of Cell Cytoplasm

1. 细胞的能量转换 : 线粒体 Energy Conversion: Mitochondria 2. 蛋白质合成装置 : 核糖体 Protein Synthesis Machine :Ribosome 3. 细胞骨架 The Cytoskeleton

线粒体的结构 Mitochondrial structure

◆外膜 (outer membrane ） ◆内膜（ inner membrane ） ◆膜间隙（ intermembrane space ） ◆基质（ matrix ） Mitochondrial structure

Outer membrane: Contains channel-forming protein, called Porin. Permeable to all molecules of 5000 daltons or less. Inner membrane (Impermeability): Contains proteins with three types of functions: (1) Electron-transport chain: Carry out oxidation reactions; (2) ATP synthase: Makes ATP in the matrix; (3) Transport proteins: Allow the passage of metabolites Intermembrane space: Contains several enzymes use ATP to phosphorylate other nucleotides. Matrix: Enzymes; Mit DNA, Ribosomes, etc.

Molecular basis of oxidative phosphorylation 线粒体的结构 Mitochondrial function

电子传递链 (Electron-transport chain)

F 1 particle is the catalytic subunit; The F 0 particle attaches to F 1 and is embedded in the inner membrane. F 1 : 5 subunits in the ratio 3  :3  :1  :1  :1  F 0: 1a ： 2b ： 12c ATP 合成酶的结构 (The structure of the ATP synthase)

F1 颗粒具有 ATP 合成酶的活性 F1 particles have ATP synthase activity

Proton translocation through F0 drives ATP synthesis by F1

ATP 合成酶是可逆的偶联装置 The ATP synthase is a reversible coupling device

化学渗透假说 Mithchell’s Chemiosmotic theory (1961) The pH and electrical gradient resulting from transport of protons links oxidation to phosphorylation; Electrons pass from NADH or FADH2 to O2, the terminal electron acceptor, through a chain of carriers in the inner membrane; As electrons move through the electron-transport chain, H+ are pumped out across the inner membrane, and form Proton motive force.

质子动力势 Proton motive force

Transport of electrons from NADH

核糖体 Ribosome Ribosomes are about 20nm in diameter and are composed of 65% ribosomal RNA and 35% ribosomal proteins. Prokaryotes have 70S ribosomes, each consisting of a small (30S) and a large (50S) subunit Eukaryotes have 80S ribosomes, each consisting of a small (40S) and a large (60S) subunit

The structure of ribosome

The activity sites of ribosome

微管 Microtubules 微管 Microtubules 微丝 Microfilament 微丝 Microfilament 中间纤维 Intermediate filaments 中间纤维 Intermediate filaments 细胞骨架 cytoskeleton

细胞骨架的主要功能 Key to Cytoskeleton functions

The intracellular distribution of Microtubules, Microfilaments and intermediate filaments.

微管的结构与组成 structure and constitute of microtubules

SingletDoubleTriplet A B A B C In cilia and flagella In centrioles and basal bodies 三类微管存在方式 Three types of structures of microtubules

纤毛与鞭毛的结构 Structure of cilia and flagella

微管的动态不稳定性 dynamic instability of microtubules

微管的功能 The functions of microtubules 1 、纺锤体和染色体运动 Mitotic spindle and Chromosome movement 2 、维持细胞形态 Maintain the cell shape 3 、 细胞内物质的运输 Transport of intracellular substance 4 、特化细胞结构（纤毛、鞭毛）的运动 The movement of cilia and flagella

纺锤体和染色体运动 Mitotic spindle and Chromosome movement

细胞内物质的运输 Transport of intracellular substance

A general model for kinesin- and dynein-mediated transport in a typical cell

特化细胞结构（纤毛、鞭毛）的运动 The movement of cilia and flagella Movement format of flagella and cilia

微丝 (microfilament, MF) MF also called actin filaments, which are thin and flexible filaments, approximately 7nm in diameter. MF also called actin filaments, which are thin and flexible filaments, approximately 7nm in diameter.

单体肌动蛋白 monomeric G-actin

微丝的装配 Assembly and structure of actin filaments Structure of an actin monomer

Assembly of actin filaments

微丝的功能 Function of microfilament 维持细胞形态, 赋予质膜强度 Maintain shape of cell, endow plasma membrane with intensity 参与肌肉受缩 Muscle contraction 参与胞质分裂 Participate in plasma division

Maintain shape of cell, endow plasma membrane with intensity

Muscle contraction

Participate in plasma division

中间纤维（ intermediate filament,IF) 10 nm filaments, called intermediates ◆ 10 nm filaments, called intermediates their diameter : between the thin actin- containing filaments and the thicker myosin filaments of smooth muscle cells their diameter : between the thin actin- ◆ containing filaments and the thicker myosin filaments of smooth muscle cells

Classes of intermediate filaments

Assembly of IF

中间纤维的功能 Function of intermediate filament ◆ Increase mechanical strength ◆ Forming and maintain of desmosome ◆ Structural support for contractile machinery in muscle cell ◆ Signaling for intracellar mechanical and molecular signals ◆ Transport of mRNA

增强了抗机械压力的能力 Increase Mechanical strength

参与了桥粒的形成与维持 Forming and maintain of desmosome