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PLASMA MEMBRANE

PLASMA MEMBRANE. Phospholipid. Plasma 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. Plasma Membrane - cont.

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PLASMA MEMBRANE

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  1. PLASMA MEMBRANE

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

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

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

  9. extracellular fluid intracellular fluid Symport Transport Protein • Translocate 2 different solutessimultaneously in same direction.

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

  11. 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.

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

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

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

  15. 3% Na solution 97% H2O 1% Na 99% H2O Red Blood Cell Hypotonic • A solution with a lower solute concentrationcompared to another solution.

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

  17. Movement of H2O • Water will “ALWAYS”diffuses down a concentration gradient from a HYPOTONICsolution to a HYPERTONICsolution. “ALWAYS REMEMBER” • HYPOTONIC HYPERTONIC

  18. 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

  19. 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.

  20. 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.

  21. 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

  22. intracellular fluid extracellular fluid K+ K+ Na+ Na+ Sodium-Potassium Pump • The mechanism that uses energy (active transport) released from splitting ATPto transport Sodium (Na+) out of and Potassium (K+) into cells.

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

  24. Answer: • Exocytosis and Endocytosis

  25. Exocytosis • Cell secretes macromolecules (proteins and other biochemicals) out of cell. • Part of the Endomembrane System: the fusion of transport vesicles with plasma membrane.

  26. Endocytosis • The energy requiring movement of particles(foreign or natural)into the cell. • 3 types of endocytosis: A. Phagocytosis B. Pinocytosis C. Receptor-mediated endocytosis

  27. Bacteria Food Vacuole White Blood Cell A. Phagocytosis • Cell eating: cells engulf particles with pseudopodia and pinches off a food vacuole. • Two examples: 1. White Blood Cell 2. Amoeba

  28. Food Particles Hyphae B. Pinocytosis • Cell drinking: droplets of extracellular fluid are absorbedinto the cell by small vesicles. • Example: 1. Fungi

  29. Liver Cell Hormones Receptors C. Receptor-Mediated Endocytosis • Importing specific macromolecules (hormones)into the cell by the inward budding of vesiclesformed from coated pits (receptors).

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