Membrane structure, I

Membrane structure, I

Membrane Structure & Function Jobs of the cell membrane Isolate the cytoplasm from the external environment Regulate the exchange of substances Communicate with other cells Identification Membrane structure Semi-permeable barrier few molecules are allowed across while keeping the majority of

produced chemicals inside the cell Phospholipid bilayer phospholipids aligned tail to tail Amphipathic hydrophobic region forms between the hydrophilic heads on the inner and outer surfaces http://telstar.ote.cmu.edu/Hughes/tutorial/cellmembranes/orient2.swf Fluid-mosaic model~ Proteins (the mosaic)

are embedded in lipids (the fluid) Phospholipids are not bonded to each other, which makes the double layer fluid http://telstar.ote.cmu.edu/Hughes/tutorial/cellmembranes/bil.swf Membrane structure Phospholipids~ membrane fluidity Cholesterol~ membrane stabilization Membrane carbohydrates ~ cell to cell recognition

Oligosaccharides (cell markers) Glycolipids Glycoproteins Membrane proteins ~ transport / communication Membrane Proteins 2 types:

Integral proteins~ transmembrane proteins Peripheral proteins~ surface of membrane Membrane protein function: Transport Proteins regulate movement of substance Carrier Proteins "grabs" certain molecules and pulls them into the cell Gated Channels

similar to carrier proteins, not always "open" Enzyme activity control metabolic pathways Receptor Proteins (Signal Transduction) set off cell responses (release of hormones or opening of channel proteins) Recognition Proteins

idenitfy cells to the immune system http://trc.ucdavis.edu/biosci10v/bis10v/media/ch03/membrane_proteins_v2.html Transport Proteins: Uniport - one molecule in one direction. Symport - Two different molecules in one direction. Antiport - Two molecules in opposite directions. http://highered.mcgraw-hill.com/sites/0072437316/student_view0/chapter6/animations.html# Transport Across Membrane 2 types:

Passive transport No energy Active transport energy http://www.northland.cc.mn.us/biology/Biology1111/animations/transport1.html Traffic of molecules across the membrane Pass freely:

Hydrophobic molecules (Hydrocarbons and O2) Small polar uncharged molecules (H2O and CO2) Pass with help: Ions ( H+, Na+, Cl-). Cant pass: Large polar uncharged molecules (sugar) Passive Transport Diffusion of a substance across

a biological membrane Diffusion ~ molecules move from high concentration to low concentration down a concentration gradient Facilitation Diffusion ~ assisted by proteins (channel or carrier proteins) Osmosis~

the diffusion of water across a selectively permeable membrane http://www.stolaf.edu/people/giannini/flashanimat/transport/osmosis.swf http://www.bbc.co.uk/education/asguru/biology/01cellb iology/05pathways/07passivefacilitated/index.shtml http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__how_diffusion_works.html A substance will diffuse from where it is more concentrated to where it is less concentrated, down its concentration gradient. Each substance diffuses down its own concentration gradient, independent of the concentration gradients of other substances. The concentration gradient represents potential energy and drives diffusion.

Diffusion Movie Water balance Osmoregulation~ control of water balance Solution~ mix of solute (dissolved) and a solvent (dissolving) Hypertonic~ solution with higher concentration of solutes Hypotonic~ solution with lower concentration of solutes IMPORTANT: The hypertonic solution has a lower water concentration than the hypotonic solution Isotonic~ equal concentrations of

solutes Water balance in living cells Cells with Walls in environment: Hypotonic = Turgid (very firm) Isotonic = Flaccid (limp) Hypertonic = Plasmolysis~ plasma membrane pulls away from cell wall Cells without Walls in environment:

Hypotonic = Lyse (explode) Isotonic = Normal Hypertonic = Crenate (Shrivel) http://www.linkpublishing.com/video-transport.htm#Osmosis_-_Red_Onion http://ccollege.hccs.edu/instru/Biology/AllStudyPages/Diffusion_Osmosis/Elodeagif.swf Specialized Transport Active transport~ movement of a substance against its concentration gradient with the help of cellular energy Low High

Types of Active Transport Sodium-potassium pump Actively maintains the gradient of Na+ and K+ ions across the membrane Antiport energized by ATP Neurons use sodium-potassium pumps Proton Pump transports Hydrogen ions

Chloroplasts and Mitochondria http://highered.mcgraw-hill.com/sites/0072437316/student_view0/chapter6/animations.html# http://multimedia.mcb.harvard.edu/media.html Endocytosis and Exocytosis Exocytosis~ secretion of macromolecules by the fusion of vesicles with the plasma membrane Endocytosis~ import of macromolecules by forming new vesicles with the plasma

membrane Phagocytosis (solid) Pinocytosis (liquid) receptor-mediated endocytosis (specific materials) http://www.johnkyrk.com/cellmembrane.html http://highered.mcgraw-hill.com/sites/0072437316/student_view0/chapter6/animations.html #

Recently Viewed Presentations

  • The links between IP Crime and Organized Crime 18.05.2011

    The links between IP Crime and Organized Crime 18.05.2011

    The links between IP Crime and Organized Crime. Dr.sc. ArtaBilalli-Zendeli. ... As having a low risk of prosecution with light penalties, related to the large profits to be achieved. ... Everything can be counterfeited : branded clothings, spirits, ciggarettes, toys,...
  • The Cattle of The Sun God - Ms. Dowling Murphy's English

    The Cattle of The Sun God - Ms. Dowling Murphy's English

    The Cattle . of The Sun God. ByBilly Wilkinson, Aj Uhl, andEoghan McGee. Setting. ... tatles on Odysseus my main man, to Helios.Hermes- The messenger of the Gods. ... - Odysseus sails along the remains of the ship to arrive...
  • Newtonian Mechanics

    Newtonian Mechanics

    Types of Forces: Centripetal Force. NOTE: A centripetal force can be a frictional force, gravitational force, or any other force. Basically, it is another force that is causing an object to go in uniform circular motion. For instance, the gravitational...
  • Winnipeg Regional Health Authority Regional SECURITY Program Prepared

    Winnipeg Regional Health Authority Regional SECURITY Program Prepared

    Winnipeg Regional Health Authority Regional SECURITY Program Prepared by: Robert Lechow Regional Manager, Security Services Regional SECURITY Program Mandate: To provide Regional direction & support in areas of crime prevention, investigations and the protection of property & human resources.
  • Key Stage 2 SATs - Victoria Dock Primary School

    Key Stage 2 SATs - Victoria Dock Primary School

    Key Stage 2 SATs Changes. In 2014/15 a new national curriculum framework was introduced by the government for Years 1, 3, 4 and 5. From 2015/16 children in all years at Key Stage 1 and 2 are expected to study...
  • begin - Coe College

    begin - Coe College

    Times New Roman Arial Monotype Sorts Wingdings blank2 The Visual System: Feature Detection Model Cortical Mechanisms Feature Detection Model Simple Cells Simple Cells Simple Cells Complex Cells PowerPoint Presentation Hypercomplex Cells Feature Detection Theory
  • ReadTT to Write with TBEAR RESOURCES for Writing

    ReadTT to Write with TBEAR RESOURCES for Writing

    Cities and towns had no indoor plumbing, running water, or fire hydrants, so water from a pond, river, or well had to be carried to the fire in buckets. When a fire broke out, everyone ran to help. They formed...
  • First Things First - West Virginia Department of Education

    First Things First - West Virginia Department of Education

    CHANGE Change is: A PROCESS, not an event Made by INDIVIDUALS first, then by the organization A highly PERSONAL experience DEVELOPMENTAL growth in both feelings and skills Hord & Loucks Taking Charge of Change Nurtured Optimism Every day, we have...