BIOLOGY CONCEPTS & CONNECTIONS Fourth Edition Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Neil A. Campbell Jane B. Reece Lawrence G. Mitchell Martha R. Taylor From PowerPoint ® Lectures for Biology: Concepts & Connections CHAPTER 5 The Working Cell Modules 5.10 – 5.21
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Cell membranes controls entry and exit of materials into the cell CELL MEMBRANE STRUCTURE AND FUNCTION Cytoplasm Figure 5.10 Membranes are selectively permeable or semipermeable (some substances can pass throught it, while others cannot).
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings The cell membrane has 2 major components: 1. A double layer of phospholipids (lipid bilayer) 2. Protein molecules that serve as channels, pumps or receptors for communication. Your teacher will draw this on the board for you to copy.
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Phospholipids are the main structural components of membranes They each have a hydrophilic head and two hydrophobic tails 5.11 Membrane phospholipids form a bilayer Head Symbol Tails Figure 5.11A Don’t copy this into notes
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings In water, phospholipids form a stable bilayer Figure 5.11B Hydrophilic heads Hydrophobic tails Water –The heads face outward and the tails face inward Don’t copy this into notes
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings The plasma membrane of an animal cell Fibers of the extracellular matrix Figure 5.12 Glycoprotein Carbohydrate (of glycoprotein) Microfilaments of the cytoskeleton Phospholipid Cholesterol Proteins CYTOPLASM Glycolipid Don’t copy this into notes
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Proteins that serve as channels Others transport substances across the membrane 5.13 Proteins make the membrane a mosaic of function Transport Figure 5.13
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings STOP for demonstration
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Your cells can move some substances across their membranes using NO ENERGY!
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Background Information on Diffusion - Diffusion is a process where molecules move from a region of higher concentration to a region of lower concentration. - The difference in concentration on either side of a membrane is known as a concentration gradient.
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Background Information on Diffusion - Diffusion of water molecules across a membrane is known as osmosis. - Diffusion will occur until an equilibrium is reached. (some will move each direction in equal amounts)
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Transport Across the Cell Membrane The cell uses 2 types of transport: 1. Passive transport - Passive transport requires NO ENERGY use by the cell. Substances move along a concentration gradient.
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings a. Molecules may be moved through a process called simple diffusion. 1. Passive transport continued… - Examples:Water, oxygen, carbon dioxide, lipid soluble molecules
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings 1. Passive transport continued… b. Facilitated diffusion - Uses carrier proteins to transport molecules that are not lipid soluble - Examples: glucose, some ions – sodium, potassium
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings What can go across membrane online.com/objects/index_tj.asp?obj id=AP1101
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings ogy1111/animations/transport1.html Link to illustrate passive transport
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings 2. Active Transport - This transport requires the cell to USE ENERGY - Examples: large compounds or when molecules are moved against the concentration gradient.
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Leave room in your notes (about ¾ page) to write notes At home on active transport
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings What will happen to a plant or animal cell when placed in fresh or salt water?
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Background Information Hypertonic – Solution that has a higher concentration of Solute than a surrounding solution Hypotonic – Solution that has a lower concentration of solute than a surrounding Solution Isotonic – Two solutions have the same solute concentrations