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CELL MEMBRANE

CELL MEMBRANE. Phospholipid. Cell Membrane. Boundary that separates the living cell from it’s non-living surroundings. Phospholipid bilayer Amphipathic - having both: hydrophilic heads hydrophobic tails ~8 nm thick. Transport protein. Cell Membrane - cont.

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CELL MEMBRANE

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  1. CELL MEMBRANE

  2. Phospholipid CellMembrane • Boundary that separates the living cellfrom it’s non-living surroundings. • Phospholipid bilayer • Amphipathic - having both: hydrophilic heads hydrophobic tails • ~8 nm thick

  3. Transport protein Cell Membrane - cont. • Controls traffic into and out of the cell with phospholipids and transport proteins. • Selectively permeable

  4. Selective Permeability • The property of biological membranes which allows some substances to cross more easily than others.

  5. Fluid Mosaic Model • 1972 - Singer and Nicolson called the membrane a “Fluid Mosaic Model”. • Mosaic: different proteins embedded in the phospholipids. • Fluid: proteins and phospholipids can move freely in the membrane.

  6. Fluid Mosaic Model- cont. • Components of a phospholipid bilayer. 1. phospholipids 2. proteins - enzymes, receptors, transport. 3. glycolipids 4. glycoproteins 5. carbohydrates 6. cholesterol

  7. Animal Cell’s Cell Membrane

  8. What are typical roles of proteins in the cell membrane?

  9. Some Functions of Membrane Proteins

  10. H

  11. What is Diffusion?

  12. Diffusion • The net movement of a substance (molecules) down a concentrationgradientfrom an area of highconcentrationto an area of lowconcentration. • passive transport: NOenergy is expended. • facilitated diffusion: type of passive transport which uses transport proteins.

  13. What is osmosis?

  14. Osmosis • The movement of water across selectively permeable membranes. • The water moves from a high concentrationto low concentration.

  15. Question:What’s in a Solution? Answer: • solute + solventsolution • NaCl + H20saltwater

  16. solution 3% NaCl 5% NaCl 97% H2O 95% H2O Red Blood Cell Hypertonic • A solution with a greater soluteconcentration compared to another solution.

  17. 3% NaCl solution 97% H2O 1% NaCl 99% H2O Red Blood Cell Hypotonic • A solution with a lower solute concentrationcompared to another solution.

  18. The contractile vacuole of Paramecium: an evolutionary adaptation for osmoregulation

  19. Movement of H2O • Water will “ALWAYS”diffuses down a concentration gradient from a HYPOTONICsolution to a HYPERTONICsolution. “ALWAYS REMEMBER” • HYPOTONIC HYPERTONIC • Water flows towards the solutes!!

  20. solution 3%NaCl 97% H2O 3%NaCl 97% H2O Red Blood Cell Isotonic • A solution with an equal solute concentrationcompared to another solution.

  21. Do Water Molecules Stop Moving in Isotonic Conditions? • No. • They continue to diffuse, however there is no net movement! • In general, which way does water move? • From hypotonic to hypertonic!

  22. Elodea in Distilled Water

  23. Elodea in Salt Water

  24. ? ?

  25. Which way will the water move?

  26. WHY?

  27. Water Water plasma membrane Cell Wall Water Plant Cells • When the plasma membrane pulls away from the cell wall(vacuole empty) in a hypertonic environment(loss of water)is called PLASMOLYSIS.

  28. Water Water Central Vacuole Cell Wall Water Plant Cells • Firmness or tension (vacuole full) that is found in plant cells (cell wall) that are in a hypotonic environment is called TURGID. • This process is called TURGOR PRESSURE.

  29. Water Balance in Cells

  30. A watered tomato plant regains its turgor

  31. Red Blood Cells Animal Cells • Animal cells placed into a hypotonic solution will HEMOLYSIS (EXPLODE). • Animal cells placed into a hypertonic solutionwill CRENATE (SHRIVEL). Hemolysis Crenation

  32. Facilitated Diffusion • Diffusion of solutes with the help of transport proteins. (passive transport) • Example: How glucose enters cells • Why do these solutes need a protein to facilitate their diffusion?

  33. That’s right! Because they are too polar or too large to pass through the lipid bilayer

  34. Diffusion and Osmosis Animations http://highered.mheducation.com/sites/9834092339/student_view0/chapter5/how_osmosis_works.html http://highered.mheducation.com/sites/9834092339/student_view0/chapter5/animation_-_osmosis.html http://highered.mheducation.com/sites/9834092339/student_view0/chapter5/how_diffusion_works.html http://highered.mheducation.com/sites/9834092339/student_view0/chapter5/diffusion_through_cell_membranes.html Amoeba Sisters - Cell Membrane https://www.youtube.com/watch?v=L-osEc07vMs&vl=en - Osmosis and Water Potential https://www.youtube.com/watch?v=Ptmlvtei8hw&list=PLM_5CERQ41W9bEVIIUt5n-dnEb9mPGO3W - Cell Transport https://www.youtube.com/watch?v=qBCVVszQQNs&list=PLwL0Myd7Dk1F0iQPGrjehze3eDpco1eVz&index=14 - Inside the Cell  Membrane Facilitated Diffusion Animation http://highered.mheducation.com/sites/9834092339/student_view0/chapter5/how_facilitated_diffusion_works.html

  35. Two Models for Facilitated Diffusion Channel Protein Carrier Protein

  36. Active Transport • The movement of molecules(small or large) across the plasma membrane in which energy (ATP)is required. • Examples: 1. Sodium (Na) - Potassium (K) Pump 2. Exocytosis 3. Endocytosis

  37. Review of Passive and Active Transport:

  38. A transport protein that generates voltage across a membrane is called an electrogenic pump. • One example is the sodium potassium pump

  39. The Sodium-Potassium Pump: a Specific Case of Active Transport

  40. Active Transport Animations: Sodium-Potassium Pump: http://highered.mheducation.com/sites/9834092339/student_view0/chapter5/sodium-potassium_exchange_pump.html http://highered.mheducation.com/sites/0072495855/student_view0/chapter2/animation__how_the_sodium_potassium_pump_works.html Proton Pumps: http://highered.mheducation.com/olc/dl/120068/bio05.swf http://highered.mheducation.com/sites/9834092339/student_view0/chapter5/proton_pump.html Endocytosis and Exocytosis: http://highered.mheducation.com/olc/dl/120068/bio02.swf

  41. Proton pumps are the main electrogenic pumps of bacteria, fungi and plants.

  42. Transport Proteins • Transportsmolecules or ions across biological membranes using active transport. • 3 types of transport proteins: 1. uniport 2. symport 3. antiport

  43. extracellular fluid intracellular fluid Uniport Transport Protein • Carries a single soluteacross the membrane.

  44. extracellular fluid intracellular fluid Symport Transport Protein • Translocates 2 different solutes simultaneously in same direction. • Ex: amino acids that enter the intestine require simultaneous binding of Na and an amino acid to the same transport protein.

  45. extracellular fluid intracellular fluid Antiport Transport Protein • Exchanges 2 solutesby transporting them in opposite directions.

  46. intracellular fluid extracellular fluid K+ K+ Na+ Na+ Sodium-Potassium Pump • This antiport uses energy (active transport) released from splitting ATPto transport Sodium (Na+) out of and Potassium (K+) into cells.

  47. What is cotransport ?

  48. Question: • How are large molecules transported into and out of the plasma membranes?

  49. Answer: • Endocytosis and Exocytosis

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