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5.6 Facilitated Diffusion

5.6 Facilitated Diffusion. Type of passive transport (no energy!) High to low concentration For molecules that cannot diffuse across the membrane on their own. Transport proteins are used. 5.6 Facilitated Diffusion. Transport proteins are specific for the substrate,

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5.6 Facilitated Diffusion

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  1. 5.6 Facilitated Diffusion Type of passive transport (no energy!) High to low concentration For molecules that cannot diffuse across the membrane on their own. Transport proteins are used

  2. 5.6 Facilitated Diffusion • Transport proteins are specific for the substrate, • The substrate can be sugars, amino acids, ions, and even water

  3. 5.6 Facilitated Diffusion • Channel Protein: becomes a hydrophilic tunnel for passage

  4. 5.6 Facilitated Diffusion • Carrier protein: binds to its passenger, changes its shape, and releases its passenger on the other side

  5. 5.7 TALKING ABOUT SCIENCE:Auquaporins • Peter Agre researched membrane proteins • Led to discovery of aquaporins

  6. 5.7 TALKING ABOUT SCIENCE:Auquaporins • Aquaporin: allows for rapid diffusion of water into and out of cells (plant cells, kidney cells, RBCs)

  7. 5.8 Active Transport • Cells have a mechanism for moving a solute against its concentration gradient • Requires energy (ATP) • The mechanism alters the shape of the membrane protein through phosphorylation using ATP

  8. Transport protein Solute Solute binding 1

  9. Transport protein Solute Solute binding Phosphorylation 1 2

  10. Transport protein Protein changes shape Solute Solute binding Phosphorylation Transport 1 2 3

  11. Transport protein Phosphate detaches Protein changes shape Solute Protein reversion Solute binding Phosphorylation Transport 4 1 2 3

  12. 5.8 Active Transport • Cells actively transport Ca2+ out of the cell. • Is calcium more concentrated inside or outside of the cell?

  13. 5.8 Active Transport

  14. 5.9 Exocytosis • used to export bulky molecules, such as proteins or polysaccharides • material to be transported is packaged within a vesicle that fuses with the membrane • Example: the excretion of insulin by cells within the pancreas into the bloodstream

  15. 5.9 Endocytosis • used to import substances useful to the livelihood of the cell • material to be transported is packaged within a vesicle that fuses with the membrane • There are 3 kinds of endocytosis

  16. Phagocytosis: • engulfment of a solid particle by wrapping cell membrane around it, forming a vacuole Phagocytosis EXTRACELLULAR FLUID CYTOPLASM Pseudopodium Food being ingested “Food” or other particle Food vacuole

  17. Pinocytosis • is the same thing except that fluids are taken into small vesicles Pinocytosis Plasma membrane Vesicle Plasma membrane

  18. Receptor-mediated endocytosis • is where receptors in a receptor-coated pit interact with a specific protein, initiating formation of a vesicle Plasma membrane Receptor-mediated endocytosis Coat protein Receptor Coated vesicle Coated pit Coated pit Specific molecule Material bound to receptor proteins

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