1 / 23

Chapter 7 and 11 Membrane “ Strunction ”

Chapter 7 and 11 Membrane “ Strunction ”. Fluid Mosaic Model. Fluidity : P.Membrane (PM) held together by weak hydrophobic interactions Lateral drifting ability Lipids Proteins: some stable/attached to cytoskeleton Temperature Dependent. “Mosaic”. Protein collage: >50 proteins

tuan
Download Presentation

Chapter 7 and 11 Membrane “ Strunction ”

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Chapter 7 and 11 Membrane “Strunction”

  2. Fluid Mosaic Model Fluidity: • P.Membrane (PM) held together by weak hydrophobic interactions • Lateral drifting ability • Lipids • Proteins: some stable/attached to cytoskeleton • Temperature Dependent

  3. “Mosaic” • Protein collage: >50 proteins • Classes: • Integral Proteins: • Transmembrane proteins • Penetrate hydrophobic core of membrane • Peripheral • Loosely bound to surface • Attached to cyto-skeleton or ECM (Extracellular matrix)

  4. Review: What organelles are responsible for creating membrane proteins?

  5. Selective Permeability General rule: like dissolves like • Non-polar/hydrophobic solutes dissolve in lipid • Ions and hydrophillic solutes dissolve in water Selective Permeability: some substances can pass more easily than others • CO2 , hydrocarbons, lipids, and O2 are nonpolar (can pass lipid membrane core easily) • Water, glucose, sugars, charged ions (cannot pass lipid core easily)  so must use hydrophillic transport proteins to pass (ex. Aquaporins) • Small molecules are more permeable than larger ones

  6. Passive Transport • Mvmt down [gradient] • Spontaneous process –ΔG • Types of Passive Transport: • Diffusion • Osmosis • Facilitated Diffusion

  7. Diffusion • Diffusion – molecules of any substance moves down [gradient]

  8. Osmosis • Osmosis (tonicity dependent) • Isotonic vs. hypotonic vs. hypertonic conditions • Water always moves from hypotonic to hypertonic side

  9. Balancing Water Uptake • Animals: cannot tolerate change in tonicity • Ex. Salt water fish vs. fresh water fish, vice versa • Some Freshwater protists prevent lysing due to contractile vacuoles

  10. Balancing Water Uptake • Plants: Cell walls help maintain water balance • Turgid Conditions Good! • Flacid Conditions cause plasmolysis • (lab 1E review)

  11. Function of Membrane Proteins • Ex. Gap Junctions, Tight Junctions, etc. • substrates bind to protein surface  sends a signal within the cell to start a chemical chain reaction or cell response • protein channels for passive transport • protein pumps for active transport • oligosaccharides on proteins or lipids act as “name tags” for cells. • Catalysis of Chemical Reactions at the Membrane Surface • Maintenance of Cell Shape End of Slide Show

  12. Facilitated Diffusion • diffusion of solutes (ions) with help from channel proteins in the plasma membrane

  13. Active Transport • Movement against [gradient] • Nonspontaneous, + ΔG, Requires ATP • Types: • Protein pumps • Cotransport • Exocytosis: Phagocytosis and Pinocytosis • Endocytosis • Receptor Mediated Endocytosis

  14. Active Transport generates an electrochemical gradient: charge difference (disequilibrium) between both sides of the membrane

  15. Protein Pumps Ex 1: Sodium-Potassium Pump (take notes about the function of Na/K pump from the video) Sodium-Potassium Pump 3-D overview Ex 2: Pumping H+ ions into lysosome to create acidic env’t

  16. H+ H+ H+ H+ H+ H+ Co-transport • Involves the transport of a substance against a concentration gradient powered indirectly by an ATP powered pump ATP ADP + Pi

  17. Exocytosis Fusing of vesicles to the plama membrane, thus releasing its contents

  18. Endocytosis • The engulfing of substances by pseudopods extensions of the plasma membrane • Three types: • Phagocytosis (cell eating – lg. particles engulfed) • Pinocytosis (cell drinking – sm. ions and liquids engulfed) • Receptor Mediated Endocytosis (use of surface proteins to engulf a specific substrate) Back to Function of Membrane Proteins

  19. Signal Transduction 3 Stages of Signal Transduction • Reception: A ligand (analogous to a substrate) binds to receptor protein. Receptor proteins can be on the cell surface, but not always. Receptor protein changes shape • Transduction: Amplifies and sends the signal through chemical relay • Cell Response: Specific response is triggered

  20. Examples of Signal Transduction Why is this hormone-receptor protein not found on the surface of the plasma membrane? Steroids and Hormones are types of lipids, which can pass through phospholipid membranes easily. Back to Function of Membrane Proteins

More Related