上游充通大学 SHANGHAI JIAO TONG UNIVERSITY Chapter 12: Lipids and Cell Membranes 脂质和细胞膜 Berg·ymoczko·Stryer Biochemistry Sixth Edition
Berg • Tymoczko • Stryer Biochemistry Sixth Edition Chapter 12: Lipids and Cell Membranes 脂质和细胞膜
上游充通大兽 Introduction SHANGHAI JIAO TONG UNIVERSITY The surface of a soap bubble is a bilayer formed by detergent 剂)molecules.肥皂泡表面是一种去污剂分子形成的脂质双层膜。 The polar heads(red)pack together,leaving the hydrophobic groups (green)in contact with air on the inside and outside of the bubble
The surface of a soap bubble is a bilayer formed by detergent (去垢 剂) molecules.肥皂泡表面是一种去污剂分子形成的脂质双层膜。 The polar heads (red) pack together, leaving the hydrophobic groups (green) in contact with air on the inside and outside of the bubble. Introduction
上游充通大兽 细胞的边界由生物膜构成 SHANGHAI JIAO TONG UNIVERSITY 生物膜确定了细胞内外的障碍，阻止细胞内分子的外泄和细 胞外不需要的物质扩散进入。细胞膜上还有特异的运输系统摄取 胞外特定分子，移出不需要分子，使细胞膜具有选择通透性。 Chromatin Nuclear envelope Nucleolus Nucleus Smooth endoplasmic reticulum Plasma 细胞膜是一种动态 Mitochondrion membrane 结构； Cytosol- Lysosome Centrioles Centrosome 细胞膜主要由脂质 matrix Rough 构成，上面有蛋白 endoplasmic reticulum 行使各种功能； Ribosomes Golgi apparatus Cytoskeletal Secretion being released from cell ·除了细胞质膜外， elements ·Microtubule by exocytosis Intermediate 细胞器也有膜结构。 filaments Peroxisome Copyright 2010 Pearson Education,Inc
• 细胞膜是一种动态 结构； • 细胞膜主要由脂质 构成，上面有蛋白 行使各种功能； • 除了细胞质膜外， 细胞器也有膜结构。 细胞的边界由生物膜构成 生物膜确定了细胞内外的障碍，阻止细胞内分子的外泄和细 胞外不需要的物质扩散进入。细胞膜上还有特异的运输系统摄取 胞外特定分子，移出不需要分子，使细胞膜具有选择通透性
上游充通大兽 Many Common Features Underlie the Diversity SHANGHAI JIAO TONG UNIVERSITY of Biological Membranes Membranes are as diverse in structure as they are in function.However, they do have in common a number of important attributes: 1.膜是层类结构，只有两个分子厚。Membranes are sheetlike structures, only two molecules thick,that form dosed boundaries between different compartments.The thickness of most membranes is between 60 A(6 nm) and 100 A(10 nm). 2.膜的主要组分是脂质和蛋白质。Membranes consist mainly of lipids and proteins.The mass ratio of lipids to proteins ranges from 1:4 to 4:1. Membranes also contain carbohydrates that are linked to lipids and proteins. 3.膜的脂质分子分为亲水和疏水两个部分。Membrane lipids are small molecules that have both hydrophilic(亲水的)and hydrophobic(疏水 的)moieties.这些脂质分子在水中能够自发形成封闭双层结构。These lipids spontaneously form closed bimolecular sheets in aqueous media. These lipid bilayers are barriers to the flow of polar molecules
Many Common Features Underlie the Diversity of Biological Membranes Membranes are as diverse in structure as they are in function. However, they do have in common a number of important attributes: 1.膜是层类结构，只有两个分子厚。Membranes are sheetlike structures, only two molecules thick, that form dosed boundaries between different compartments. The thickness of most membranes is between 60 Å (6 nm) and 100 Å (10 nm). 2.膜的主要组分是脂质和蛋白质。Membranes consist mainly of lipids and proteins. The mass ratio of lipids to proteins ranges from 1:4 to 4:1. Membranes also contain carbohydrates that are linked to lipids and proteins. 3.膜的脂质分子分为亲水和疏水两个部分。Membrane lipids are small molecules that have both hydrophilic (亲水的) and hydrophobic (疏水 的) moieties.这些脂质分子在水中能够自发形成封闭双层结构。These lipids spontaneously form closed bimolecular sheets in aqueous media. These lipid bilayers are barriers to the flow of polar molecules
上游充通大兽 SHANGHAI JIAO TONG UNIVERSITY 4.通过特殊蛋白质介导，使生物膜有不同功能。Specific proteins mediate distinctive functions of membranes.Proteins serve as pumps ( channels(通道)，receptors(受体)，energy transducers(能量传感 器)，and enzymes(酶).Membrane proteins are embedded in lipid bilayers which create suitable enviroments for their action. 5.Membranes are noncovalent assemblies.膜分子组装依依靠非共价相互 作用。The constituent protein and lipid molecules are held together by many noncovalent interactions,which act cooperatively. 6.Membranes are asymmetric.膜是非对称结构。The two faces of biological membranes always differ from each other
4.通过特殊蛋白质介导，使生物膜有不同功能。Specific proteins mediate distinctive functions of membranes. Proteins serve as pumps（泵）, channels（通道）, receptors（受体）, energy transducers（能量传感 器）, and enzymes（酶）. Membrane proteins are embedded in lipid bilayers , which create suitable enviroments for their action. 5. Membranes are noncovalent assemblies. 膜分子组装依依靠非共价相互 作用。 The constituent protein and lipid molecules are held together by many noncovalent interactions, which act cooperatively. 6. Membranes are asymmetric. 膜是非对称结构。The two faces of biological membranes always differ from each other