MEMBRANE AND TRANSPORT

1 EJC H2 Biology T2W1 Membrane Transport Membrane Transport 1. Overview of Topic Cells need to regulate the movement of substances into and out of themselves. Substances such as water, oxygen, glucose and minerals are important in the synthesis of new molecules and important cellular processes. According to the fluid mosaic model, cell membranes are selectively permeable due to the nature of the phospholipids and proteins from which they are made. The movement of different molecules depends on the nature of the substances through transport processes such as osmosis, diffusion and active transport. Membranes allow cells to create and maintain internal environments that are different from external environments. Membranes are not just found on the most exterior ends of a cell to provide that barrier between the exterio r and interior. Especially for e ukaryotic cells, there are internal membrane structures that partition the cell into specialised compartments so that cellular processes can occur with optimal activity e.g. chloroplasts and mitochondria. The endomembrane system, consisting of rough and smooth endoplasmic reticulum and Golgi apparatus, is responsible for protein processing and vesicular transport within the cell. 2. Learning Outcomes (j) explain the fluid mosaic model and the roles of the constituent biomolecules (including phospholipids, proteins, glycolipids, glycoproteins and cholesterol) in cell membranes (k) outline the functions of membranes at the surface of cells and membranes within the cell (l) explain how and why different substances move across membranes through simple diffusion, osmosis, facilitated diffusion, active transport, endocytosis and exocytosis 3. References Reece, J. B., Urry, L. A., Cain, M. L., Wasserman, S. A., Minorsky, P. V. and Jackson, R. B. (2011) Campbell Biology (Ninth Edition) (Pearson Higher Education) ISBN 0321739752

2 EJC H2 Biology T2W1 Membrane Transport Contents 1. Overview of Topic ................................ ................................ ....................... 1 2. Learning Outcomes ................................ ................................ ..................... 1 3. References ................................ ................................ ................................ . 1 4. Types of Membranes ................................ ................................ .................. 2 5. Membrane Structure: The Fluid Mosaic Model ................................ ............ 2 6. Components of Membrane ................................ ................................ .......... 4 Phospholipid ................................ ................................ ................................ ... 4 Cholesterol ................................ ................................ ................................ ..... 5 Protein ................................ ................................ ................................ ...