Biology Lecture Notes Chapter 5
Biology Lecture Notes Chapter 5 BIO-101-105
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Adriana Shania Proctor
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This 6 page Class Notes was uploaded by Adriana Proctor on Friday September 30, 2016. The Class Notes belongs to BIO-101-105 at Chesapeake College taught by Doctor Hatkoff in Fall 2016. Since its upload, it has received 3 views. For similar materials see Fundamentals of Biology I in Science at Chesapeake College.
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Date Created: 09/30/16
Biology Lecture Notes Chapter 5 Overview: Life at the Edge ● The plasma membrane exhibits selective permeability, allowing some substances to cross it more easily than others. Cellular Membranes are Fluid Mosaics of Lipids and Proteins ● Phospholipids are the most abundant lipid in most membranes ● Phospholipids are molecules containing: -Hydrophobic (the “tail”) -Hydrophilic(the “heads”) Membrane Proteins and their Functions A membrane is a collage of different proteins embedded in the fluid matrix of the lipid bilayer. ● Proteins determine most of the membrane’s specific functions. Six major functions of the membrane proteins include: 1. Transport 2. Enzymatic Activity 3. Signal transduction 4. Cell-cell recognition 5. Intercellular joining 6. Attachment to the Extra Cellular Matrix Membrane Structure results in Selective Permeability ● A cell must regulate transport of substances across cellular boundaries. ● Plasma membranes are selectively permeable, regulating the cell’s molecular traffic. ● Transport proteins allow passage of hydrophilic substances across the membrane. Types of Transport Osmosis ● Movement of WATER across THE PLASMA MEMBRANE Passive Diffusion ● Movement of a molecule down its concentration gradient across THE PLASMA MEMBRANE Facilitated Diffusion ● Movement of a molecule down its concentration gradient through A PROTEIN CHANNEL Active Transport ● Movement AGAINST its concentration gradient THROUGH A PROTEIN WITH THE USE OF ENERGY Effects of Osmosis on Water Balance Osmosis ● Movement of water across the PLASMA MEMBRANE Water Balance of Cells Without Walls ● Isotonic solution: Solute concentration is the same as inside the cell; no net water movements across the plasma membrane. ● Hypertonic solution: Solute concentration is greater that that inside the cell; cell loses water. ● Hypotonic solution: Solute concentration is less than that inside the cell; cell gains water Passive Transport is Diffusion of a Substance across a Membrane with no Energy Investment ● Passive Transport is the tendency for molecules to spread out evenly into the available space. Substances diffuse down their concentration gradien here it is more concentrated to where it is less concentrated. Passive Diffusion -Movement of a molecule down its concentration gradient across THE PLASMA MEMBRANE. Facilitated Diffusion: Passive Transport Aided by Proteins ● Facilitated Diffusion -Movement of a molecule down its concentration gradient through the protein channel. The Need for Energy in Active Transport ● Active Transport -Movement of a molecule against its concentration gradient THROUGH A PROTEIN WITH THE USE OF ENERGY. ● Active transport requires energy, usually in the form of ATP. A.) Active Transport B.)Concentration Gradient C.)O2 + CO2 D.)Facilitated Diffusion E.)Protein