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Cell membrane structure. &and functions
The document discusses the structure and functions of the plasma membrane. It describes the plasma membrane as a phospholipid bilayer composed of phospholipids with hydrophilic heads and hydrophobic tails arranged in a fluid mosaic structure. The membrane contains various proteins that facilitate transport, act as receptors, or perform other functions. The document outlines different types of membrane transport including diffusion, facilitated diffusion, osmosis, bulk transport, and active transport.
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Cell membrane structure. &and functions
- 2. Outline • Phospholipid Bilayer •Fluid Mosaic Model • Membrane Proteins • Diffusion • Facilitated Diffusion • Osmosis • Bulk Transport • Active Transport
- 3. Membrane Functions • Protection •Communication • Selectively allow substances in • Respond to environment • Recognition
- 4. Plasma Membrane • Boundarythat separates the living cell from it’s non-living surroundings. • Phospholipid bilayer • Amphipathic - having both: hydrophilic heads hydrophobic tails • ~8 nm thick • Is a dynamic structure Phospholipid
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- 6. Proteins—For Function • Transport •Receptors • Enzymes • Signal Transducers • Support
- 7. PROTEINS CAN MOVE INTHE MEMBRANE, TOO! Plasma Membrane Proteins
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- 12. Enzymatic protein Example of Enzymatic activity associated witha membrane: G-protein cascade G-PROTEIN ANIMATION 2 G proteins, also known as guanine nucleotide-binding proteins, are a family of proteins that act as molecular switches inside cells, and are involved in transmitting signals from a variety of stimuli outside a cell to its interior.
- 13. Permeability of theCell Membrane- Differentially Permeable
- 14. Permeability of theCell Membrane
- 15. • Diffusion – thepassive movement of molecules from a higher to a lower concentration until equilibrium is reached. –Gases move through plasma membranes by diffusion. • Osmosis– A special case of diffusion DIFFUSION
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- 19. Gas exchange inlungs by diffusion
- 20. Osmosis The diffusion ofwater across a differentially permeable membrane due to concentration differences
- 21. Question: What’s in aSolution? Answer: • solute + solvent solution • NaCl + H20 saltwater
- 22. TONICITY • Refers tothe concentration of SOLUTES • Is a RELATIVE term, comparing two different solutions • Hypertonic • Hypotonic • Isotonic An isotonic solution refers to two solutions having the same osmotic pressure across a semi-permeable membrane. This state allows for the free movement of water across the membrane without changing the concentration of solutes on either side.
- 23. Hypertonic • A solutionwith a greater solute concentration compared to another solution. 3% NaCl 97% H2O Red Blood Cell 5% NaCl 95% H2O solution Which way will the water move?
- 24. Hypotonic • A solutionwith a lower solute concentration compared to another solution. 3% Na 97% H2O Red Blood Cell 1% Na 99% H2O solution Which way will the water move?
- 25. Isotonic • A solutionwith an equal solute concentration compared to another solution. 3% Na 97% H2O Red Blood Cell 3% Na 97% H2O solution Which way will the water move?
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- 28. HYPERTONIC SOLUTION crenation. A roundedprojection, as on the margin of a shell. The condition or state of being crenate. A process resulting from osmosis in which red blood cells, in a hypertonic solution, undergo shrinkage and acquire a notched or scalloped surface.
- 29. • Function—Transport. Arespecific, combine with only a certain type of molecule. • Types –Facilitated transport--passive –Active transport—requires energy Carrier Proteins
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- 33. -ATPase enzyme isa solute pump that pumps sodium out of cells while pumping potassium into cells, both against their concentration gradients. This pumping is active (i.e. it uses energy from ATP) and is important for cell physiology. An example application is nerve conduction.
- 34. • Exocytosis---Cellular secretion •Endocytosis— – Phagocytosis— “Cell eating” – Pinocytosis– “Cell drinking” – Receptor-mediated endocytosis-specific particles, recognition. Exocytosis and Endocytosis Pinocytosis, a process by which liquid droplets are ingested by living cells. Pinocytosis is one type of endocytosis, the general process by which cells engulf external substances, gathering them into special membrane-bound vesicles contained within the cell.
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- 39. SUMMARY • Phospholipid Bilayer •Fluid Mosaic Model • Membrane Proteins • Diffusion • Facilitated Diffusion • Osmosis • Bulk Transport • Active Transport