Unit II Ch5 Membranes - Chapter 5 Membrane Structure and...

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Unformatted text preview: Chapter 5 Membrane Structure and Function Chapter 4 Chapter 1 Diffusion of Dye in Water Diffusion of Dye in Water Dispersing Dynamic Equilibrium Time 0 Time 1 Time 2 Reduced Steep No Concentration Concentration Concentration Gradient Gradient Gradient Solution = Solution = Gradient Solute dissolved in Solvent [ ] diff between 2 regions of space Random net movement of molecules from regions high low [ ] Molecules move down gradient No extra energy required Diffusion Faster Diffusion Slow, short distances Higher temp Smaller molecule Greater [ ] gradient Hypertonic Hypertonic Higher solutes Isotonic Equal solutes Hypotonic Lower solutes Osmosis Diffusion of H2O down its gradient across semi permeable membrane H2O moves from hyper soln hypo soln 50% Sugar 1% Starch 50% Sugar more hypertonic Osmosis Osmosis 1% Starch less hypertonic Both solutions put half­full into dialysis tubing w/semi­ permeable membrane and soaked in water = hypotonic environment for 45 min The Effects of Osmosis across semi­permeable cell membrane Shriveled RBCs Normal RBCs Swollen RBCs ypertonic Solution Isotonic Solution Hypotonic Solution Net movement of water out of cells Equal movement of water into and out of cells Net movement of water into cells RBC’s: Osmosis RBC’s: Osmosis Isotonic solution: Hypotonic solution: [ solutes ] + [ free H2O ] outside = inside cell No change in cell volume Extracellular fluid usually isotonic to cytoplasm [ solute ] inside cell > outside cell H2O follows high solutes inside cell Cell gains water Hypertonic solution: [ solute ] outside > inside cell H2O follows high solutes outside cell Cell loses water Hypertonic soln Elodea: Osmosis Elodea: Osmosis Hypotonic soln Isotonic soln Phospholipi Phospholipi d Bilayer Brown Recluse Spider venom has lipase that destroys cell membrane Phospholipid Review Phospholipid Review Fatty Acid Fatty Acid Glycerol Fatty Acid Fatty Acid Fatty Acid Glycerol Change from Change Polar group Triglyceride to Phospholipid Phospholipid Functions of Plasma Membrane Functions of Plasma Membrane 1. 2. 3. Cell = “smallest unit of life” Plasma membrane = “gatekeeper” Isolate inside from outside (phospholipids) Regulate exchange of substances inside/outside cell (proteins) Interact w/other cells + outside (proteins) Selectively Permeable; Semi­permeable Fluid Mosaic Model of Membrane Fluid Mosaic Model of Membrane Other Membrane Proteins Channel Transport Protein Enzymes Attachment Connecting Recognition Glycoprotein Receptor Protein H2O, O2, CO2, small lipid solubles pass w/out transport protein Membrane Proteins Receptor Binds specific molecules (hormones,nutrients) trigger cellular responses Receptor Signal Transduction Video Receptor Recognitio Glycoproteins, used by n immune system to tell foreign vs. self HIV glycoproteins Enzymes In/near membrane to promote chemical reactions Attachment Proteins between animal cells DESMOSOME TIGHT JUNCTION Connecting Proteins between cells Connecting Proteins bet GAP JUNCTIONS animals PLASMODESMATA plants Transport Proteins For small hydrophilic (sugars, a.a.) CHANNEL: pores for ions (K+, Na+, Ca2+), H2O GABAA Ion Channel: allosteric activation by Alcohol, Barbiturates increases Cl­ flow dampens nerve impulse = sedation Channel Protein Animation CARRIER: binding sites grab specific molecules, change shape & move across membrane Carrier Protein Animation Aquapori n Passive Transport across Membranes Passive Transport across Membranes Down gradient No extra energy Simple Diffusion Osmosis = type of simple diffusion Facilitated Diffusion w/transport protein Facilitated Facilitated Diffusion through a Carrier or Channel protein Energy Requiring Transport across Membranes Energy Requiring Transport across Membranes Against gradient Requires energy: 1 ATP per molecule Active Transport w/carrier protein Pinocytosis Endocytosis Phagocytosis Receptor mediated Exocytosis Pinocytosis ­ cell drinking Pinocytosis ­ cell drinking Phagocytosis ­ cell eating Phagocytosis ­ cell eating Ameoba engulfs paramecium WBC ingests bacterial Receptor­mediated Endocytosis ­ to recycle receptors Exocytosis ­ for secretion or expulsion Exocytosis ­ for secretion or expulsion Secreted Material (extracellular fluid) plasma membrane 2 3 Vesicle 1 (cytoplasm) ...
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