十细胞膜的转运功能.pptVIP

Basic Functions of Cells细胞的基本功能 Chen Ying-ying, PhD Dept. of Pathophysiology, Zhejiang University School of Medicine bchenyy＠zju.edu.cn a typical animal cell and its organelles 细胞器 (I) Structure of Cell membrane 细胞膜 (Plasma membrane 质膜) Under an electron microscope membranes appear to have a trilaminar structure 三层结构 Fluid Mosaic Model 液态镶嵌模型 (Singer and Nicholson, 1972) (II) Cell membrane Components Protein 蛋白质 (55 %) Lipid 脂类 Phospholipids 磷脂 (25 %) Cholesterol 胆固醇 (13%) Other lipids (4%) Carbohydrates 糖类 (3 %) (1) Membrane Lipids 膜脂 The lipids in the plasma membrane are chiefly phospholipids and cholesterol Phospholipids 磷脂 Phosphatidylcholine 卵磷脂 Sphingomyelin 鞘磷脂 Phosphatidylethanolamine 磷脂酰乙醇胺 Phosphatidylserine 磷脂酰丝氨酸 …… Phospholipids are amphiphilic 两性的 Lipid bilayer formation see flash: 02-Lipidbilayer formation Feature of lipid bilayer Fluidility 流动性 see flash: 02-Lipid fluidility The presence of the cis double bond makes prevents tight packing and makes the bilayer difficult to freeze Cholesterol 胆固醇 reduces membrane fluidility prevents crystallization (2) Membrane Proteins 膜蛋白 Integral Proteins 整合蛋白 Peripheral Proteins 外周蛋白 Integral Proteins have important hydrophobic 疏水的 interactions with the interior at the membrane (3) Membrane carbohydrates 膜糖类 (III) Function of cell membrane Selective Barrier 选择性屏障 Contain Enzyme Systems 酶系统 Contain Transport Systems 转运系统 Contain Specific Recognition Sites 特异性识别系统 Chemical compositions of extracellular and intracellular fluid 细胞外液和细胞内液的化学组成 (IV) Membrane Transport 物质转运 Relative permeability 通相对透性 of lipid bilayer Types of transport processes Simple Diffusion 单纯扩散 Facilitated Diffusion 易化扩散 Active Transport 主动转运 Endocytosis and Exocytosis 入胞和出胞 (1) Simple diffusion 单纯扩散 Diffusion 扩散: Movement of substances with the concentration gradient 浓度梯度 or?electrical gradient 电学梯度 It is a passive transport 被动转运 process Factors influencing the rate of diffusion Concentration gradient OR electrical gradient M