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Membrane Transport

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  1. Membrane Transport How stuff gets in or out

  2. Membrane Transport Objectives: • Relate membrane structures to transport processes

  3. Membrane Transport Objectives: • Relate membrane structures to transport processes • Compare and contrast types of transport processes

  4. Membrane Transport The cell membrane’s most important function is to select what goes in and out of the cell.

  5. Membrane Transport The cell membrane’s most important function is to select what goes in and out of the cell. This property is known as selective permeability.

  6. Membrane Transport Two processes allow materials to move in and out of the cell: 1) passive transport

  7. Membrane Transport Two processes allow materials to move in and out of the cell: 1) passive transport 2) active transport

  8. Passive Transport Passive transport requires No Energy (ATP).

  9. Passive Transport There are three types: • Simple diffusion

  10. Passive Transport There are three types: • Simple diffusion • Facilitated diffusion

  11. Passive Transport There are three types: • Simple diffusion • Facilitated diffusion & • Osmosis

  12. Passive Transport Simple Diffusion Substances move from a high concentration to a low concentration. This influenced by: • Temperature

  13. Passive Transport Simple Diffusion Substances move from a high concentration to a low concentration. This influenced by: • Temperature • Concentration

  14. Passive Transport Simple Diffusion Substances move from a high concentration to a low concentration. This influenced by: • Temperature • Concentration • Distance

  15. Passive Transport Simple Diffusion In the cell, only nonpolar and lipid soluble substances diffuse directly through the bilayer.

  16. . Extracellular fluid Lipid- soluble solutes Cytoplasm

  17. Passive Transport Simple Diffusion Common substances that diffuse in this manner include Oxygen and Carbon Dioxide

  18. Passive Transport Facilitated Diffusion Molecules which can not pass through the lipid bilayer because of size or polarity pass through using protein carriers or channels.

  19. Passive Transport Carriers are integral proteins and are typically designed for a specific type of molecule, for example, glucose.

  20. Passive Transport Carriers are integral proteins and are typically designed for a specific type of molecule, for example, glucose. What is meant by an integral protein?

  21. Passive Transport What is meant by an integral protein? This is a protein that transverses the entire membrane.

  22. Passive Transport Carriers are integral proteins and are typically designed for a specific type of molecule, for example, glucose. Rate is only limited by the number of carriers on the membrane.

  23. Passive Transport Channels are integral proteins that allow smaller molecules (ions and water) to pass through.

  24. Passive Transport Channels are integral proteins that allow smaller molecules (ions and water) to pass through. They can be specific for certain types of ions (Na+ or K+ )

  25. Passive Transport Channels are integral proteins that allow smaller molecules (ions and water) to pass through. They can be specific for certain types of ions (Na+ or K+ ) Some are always open while others are gated and open only when stimulated.

  26. Passive Transport

  27. Passive Transport Osmosis is the diffusion of water across a semi permeable membrane.

  28. Passive Transport Osmosis is the diffusion of water across a semi permeable membrane. Water moves depending on its concentration through channels lined with proteins called aquaporins.

  29. Passive Transport Osmosis is the diffusion of water across a semi permeable membrane. Water moves depending on its concentration through channels lined with proteins called aquaporins. It can also pass through the lipid bilayer!

  30. Passive Transport The rate of osmosisis dependent on the concentration of impermeable molecules and permeable molecules.

  31. Passive Transport In biological systems, the ability of a solution to change the shape of a cell by osmosis is called tonicity.

  32. Passive Transport Isotonic solutions do not change the shape of the cells. In the hospital these are iv solutions of 0.9% NaCl or 5% dextrose (D5W).

  33. Passive Transport Hypertonic solutions do change the shape of the cells because the concentration of impermeable solutes is greater than the cell. In the hospital these are used in cases of cerebral edema. Pulls water out of the cell.

  34. Passive Transport Hypotonic solutions do change the shape of the cells because the concentration of impermeable solutes is less than the cell. In the hospital these are used in cases of dehydration

  35. Active Transport Active transport requires Energy (ATP).

  36. Active Transport Active transport requires Energy (ATP). Substances move from a LOW to a HIGH concentration.

  37. Active Transport

  38. Active Transport Active transport requires membrane proteins that are specific for a particular substance. There are two types: • Primary Active Transport

  39. Active Transport Active transport requires membrane proteins that are specific for a particular substance. There are two types: • Primary Active Transport & • Secondary Active Transport

  40. Active Transport Primary Active Transport uses ATP directly to move a solute across the plasma membrane, against the gradient.

  41. Active Transport Primary Active Transport uses ATP directly to move a solute across the plasma membrane, against the gradient. The best example is the sodium-potassium pump.