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Plasma Membrane or Cell Membrane (Outer Layer in Animal Cells)
The document covers the structure and function of the plasma membrane, emphasizing its role in maintaining homeostasis and regulating transport in and out of the cell. It describes important concepts such as the fluid mosaic model, types of transport including diffusion, osmosis, active transport, and various forms of endocytosis and exocytosis. It also highlights the significance of transport proteins and their mechanisms in facilitating the movement of molecules across the membrane.
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Plasma Membrane or Cell Membrane (Outer Layer in Animal Cells)
- 1. Plasma Membrane Presented By: ShozabSeemab Khan 2016-mphil-1372 1
- 2. 2 The Plasma Membrane- Gateway to the Cell
- 3. 3 Cell Membrane The cellmembrane is flexible and allows a unicellular organism to move
- 4. 4 Homeostasis • Balanced internalcondition of cells • Also called equilibrium • Maintained by plasma membrane controlling what enters & leaves the cell
- 5. 5 Functions of PlasmaMembrane Protective barrier Regulate transport in & out of cell (selectively permeable) Allow cell recognition Provide anchoring sites for filaments of cytoskeleton
- 6. 6 Structure of theCell Membrane
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- 8. 8 Phospholipids Make up thecell membrane Contains 2 fatty acid chains that are nonpolar Head is polar & contains a Phosphate group
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- 10. 10 FLUID- because individualphospholipids and proteins can move around freely within the layer, like it’s a liquid. MOSAIC- because of the pattern produced by the scattered protein molecules when the membrane is viewed from above. FLUID MOSAIC MODEL
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- 13. 13 Cell Membrane Hydrophobic molecules pass easily;hydrophillic DO NOT The cell membrane is made of 2 layers of phospholipids called the lipid bilayer
- 14. 14 Solubility • Materials thatare soluble in lipids can pass through the cell membrane easily
- 15. 15 Small non-charged moleculesmove through easily. Examples: O2, and CO2 Semipermeable Membrane
- 16. 16 Ions, and largemolecules such as glucose and amino acids do not move through the membrane on their own. They must use transport proteins Semipermeable Membrane
- 17. 17 Types of Transport AcrossCell Membranes
- 18. 18 • Requires NO energy •Molecules move from area of HIGH to LOW concentration Simple Diffusion
- 19. 19 DIFFUSION Diffusion is a PASSIVEprocess which means no energy is used to make the molecules move.
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- 21. 21 Diffusion through a Membrane Cellmembrane Solute moves DOWN concentration gradient (HIGH to LOW)
- 22. 22 Osmosis • Diffusion of wateracross a membrane • Moves from HIGH Concentration to a LOW concentration Diffusion across a membrane Semipermeable membrane
- 23. 23 Diffusion of H2OAcross A Membrane High H2O potential Low solute concentration Low H2O potential High solute concentration
- 24. 24 Cell in IsotonicSolution CELL 10% NaCL 90% H2O 10% NaCL 90% H2O What is the direction of water movement? The cell is at _______________. equilibrium ENVIRONMENT NO NET MOVEMENT
- 25. 25 Cell in HypotonicSolution CELL 10% NaCL 90% H2O 20% NaCL 80% H2O What is the direction of water movement?
- 26. 26 Cell in HypertonicSolution CELL 15% NaCL 85% H2O 5% NaCL 95% H2O What is the direction of water movement? ENVIRONMENT
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- 28. 28 Isotonic Solution NO NET MOVEMENTOF H2O (equal amounts entering & leaving) Hypotonic Solution CYTOLYSIS Hypertonic Solution PLASMOLYSIS
- 29. 29 Cytolysis & Plasmolysis CytolysisPlasmolysis
- 30. 30 Three Forms ofTransport Across the Membrane
- 31. 31 Passive Transport Simple Diffusion Doesn’t require energy Moves high to low concentration Example: Oxygen diffusing in or carbon dioxide diffusing out.
- 32. 32 Passive Transport Facilitated diffusion Doesn’trequire energy Uses transport proteins to move high to low concentration Examples: Glucose or amino acids moving from blood into a cell.
- 33. 33 Proteins Are Criticalto Membrane Function
- 34. 34 Types of TransportProteins • Channel proteins are embedded in the cell membrane & have a pore for materials to cross • Carrier proteins can change shape to move material from one side of the membrane to the other
- 35. 35 Facilitated Diffusion Molecules willrandomly move through the pores in Channel Proteins.
- 36. 36 Facilitated Diffusion • SomeCarrier proteins do not extend through the membrane. • They bond and drag molecules through the lipid bilayer and release them on the opposite side.
- 37. 37 Carrier Proteins • Othercarrier proteins change shape to move materials across the cell membrane
- 38. 38 Active Transport Requires energyor ATP Moves materials from LOW to HIGH concentration AGAINST concentration gradient
- 39. 39 Active transport Sodium-Potassium Pump Examples: Pumping Na+(sodium ions) out and K+ (potassium ions) in against strong concentration gradients. Called Na+-K+ Pump
- 40. 40 Sodium-Potassium Pump 3 Na+pumped in for every 2 K+ pumped out; creates a membrane potential
- 41. 41 Moving the “BigStuff” Molecules are moved out of the cell by vesicles that fuse with the plasma membrane. Exocytosis - moving things out.
- 42. 42 Pinocytosis Most common formof endocytosis. Takes in dissolved molecules as a vesicle.
- 43. 43 Pinocytosis • Cell formsan invagination • Materials dissolve in water to be brought into cell • Called “Cell Drinking”
- 44. 44 Receptor-Mediated Endocytosis Some integralproteins have receptors on their surface to recognize & take in hormones, cholesterol, etc.
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- 46. 46 Endocytosis – Phagocytosis Usedto engulf large particles such as food, bacteria, etc. into vesicles Called “Cell Eating”
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- 48. 48 Exocytosis The opposite ofendocytosis is exocytosis. Large molecules that are manufactured in the cell are released through the cell membrane. Inside Cell Cell environment
- 49. difference Prokaryotic vs eukaryoticcell PM 49
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