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Membrane Transport

Membrane Transport. Membrane Transport. What are some substances commonly transported across membranes?. Membrane Transport. What are the three mechanisms used to move solute molecules across the membrane? Diffusion Facilitated diffusion Active transport. Simple Diffusion.

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Membrane Transport

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  1. Membrane Transport

  2. Membrane Transport • What are some substances commonly transported across membranes?

  3. Membrane Transport • What are the three mechanisms used to move solute molecules across the membrane? • Diffusion • Facilitated diffusion • Active transport

  4. Simple Diffusion • What is involved in this transport process? • Movement of molecules from an area of higher concentration to an area of lower concentration without using the cell’s energy • What can cross the plasma membrane via simple diffusion?

  5. Simple Diffusion • How does osmosis differ from simple diffusion? • Osmosis is the diffusion of water.

  6. Simple Diffusion • What are the major factors that influence diffusion across a membrane?

  7. Facilitated Diffusion • How is facilitated diffusion different from simple diffusion?

  8. Facilitated Diffusion • A type of passive transport because it moves substances down their concentration gradient without using the cell’s energy. • Carrier proteins are used to transport specific substances down their concentration gradient.

  9. Carrier Proteins • Transport proteins that can bind to specific substances on one side of the cell membrane, carry the substance across the cell membrane and release it one the other side

  10. Facilitated Diffusion

  11. Facilitated Diffusion • What do we specifically know about the transport of glucose in red blood cells?

  12. Active Transport • How is active transport similar to and different from facilitated diffusion? • Transport of a substance across the cell membrane against its concentration gradient • Molecules move from a lower concentration to a higher concentration • Requires the cells to use energy (ATP)

  13. Active Transport • What do we currently know about the sodium-potassium pump?

  14. Sodium-Potassium Pump • Na+=sodium ions • K+= potassium ions • Transports 3 sodium ions (Na+) out of the cell and 2 potassium ions (K+) into the cell • Na+ concentration is higher outside the cell • K+ concentration is higher inside the cell • Ions move against their concentration gradient • ATP is needed • Look on page 82 at Figure 4-5.

  15. Active Transport

  16. Active Transport • Why is this sodium-potassium pump so important for animal cells? • Prevents Na+ from accumulating in the cell and this would be toxic to the cell • Helps maintain the concentration gradients of Na+ and K+. Many cells use the Na+ gradient to help transport other substances such as glucose across the membrane.

  17. Active Transport

  18. Vesicles Move Substances Across Membranes • Endocytosis= the movement of a substance into a cell by a vesicle • Exocytosis= the movement of a substance by a vesicle to the outside of a cell

  19. http://www.emc.maricopa.edu/faculty/farabee/BIOBK/endocytosis.gifhttp://www.emc.maricopa.edu/faculty/farabee/BIOBK/endocytosis.gif

  20. Membrane Receptor Proteins Receive Information • Cells must respond to information and filter out unimportant information. • In order to receive messages carried by signal molecules, the cell membrane contains specialized proteins called receptor proteins that are able to bind to these molecules.

  21. http://www.scq.ubc.ca/wp-content/uploads/2006/07/transduction.gifhttp://www.scq.ubc.ca/wp-content/uploads/2006/07/transduction.gif

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