1. Cell Transport

2. Ch. 9: Cell Transport Passive Transport Passive Transport Targets Targets Distinguish between diffusion & osmosis Distinguish between diffusion & osmosis Define equilibrium & explain how it is established Define equilibrium & explain how it is established Explain what is meant by a concentration gradient Explain what is meant by a concentration gradient Explain how substances cross the cell membrane through facilitated diffusion Explain how substances cross the cell membrane through facilitated diffusion Explain how ion channels assist the diffusion of ions across the cell membrane Explain how ion channels assist the diffusion of ions across the cell membrane

3. Concentration how much of a given substance there is mixed with another substance how much of a given substance there is mixed with another substance

4. Kinetic Motion Kinetic Motion All particles of matter are in constant (random) motion All particles of matter are in constant (random) motion Molecules travels in a straight line until they hit something, bounce off, and travel in a new direction Molecules travels in a straight line until they hit something, bounce off, and travel in a new direction Molecules move down the concentration gradient from an area more concentrated to an area less concentrated Molecules move down the concentration gradient from an area more concentrated to an area less concentrated

5. Concentration Gradient Difference in concentration of a substance across a space Difference in concentration of a substance across a space

6. Types of Cellular Transport Passive Transport Passive Transport cell doesn’t use energy 1. Diffusion 2. Facilitated Diffusion 3. Osmosis Active Transport Active Transport cell does use energy 1. Protein Pumps 2. Endocytosis 3. Exocytosis high low This is gonna be hard work!! high low Weeee!! ! Animations of Active Transport & Passive TransportAnimations

7. Passive Transport Passive Transport Diffusion - - Movement of molecules from an area of higher concentration to an area of lower concentration - - Driven entirely by the kinetic motion of molecules - - Continues until the concentration of molecules is the same throughout the space they occupy

8. Factors Affecting Diffusion Rate

9. Equilibrium Exists when the concentration of the molecules of a substance is the same throughout a space Exists when the concentration of the molecules of a substance is the same throughout a space Random motion of molecules continues so equilibrium is maintained (no concentrated gradient) Random motion of molecules continues so equilibrium is maintained (no concentrated gradient)

10. Diffusion Across Membranes Diffusion Across Membranes right guard commercial Diffusion Across Membranes Cell membranes are selectively permeable Cell membranes are selectively permeable Phospholipid bilayer (non-polar) Phospholipid bilayer (non-polar) Diffusion depends on size, type of molecule, & chemical nature of molecule Diffusion depends on size, type of molecule, & chemical nature of molecule

11. 3. Structure of cell membrane Lipid Bilayer -2 layers of phospholipids a. Phosphate head is polar (water loving) b. Fatty acid tails non-polar (water fearing) c. Proteins embedded in membrane About Cell Membranes (continued) Phospholipid Lipid Bilayer

13. Diffusion Across Membranes Non-polar molecules (O 2 & CO 2 ) can dissolve in lipid bilayer and thus pass through by diffusion Non-polar molecules (O 2 & CO 2 ) can dissolve in lipid bilayer and thus pass through by diffusion Very small insoluble molecules may pass through membrane pores by diffusion Very small insoluble molecules may pass through membrane pores by diffusion Large or Polar substances move through membrane with help from transport proteins as do ions Large or Polar substances move through membrane with help from transport proteins as do ions

15. Osmosis Osmosis Osmosis Osmosis Diffusion of water molecules through a cell membrane from an area of higher water molecule concentration to an area of lower concentration Diffusion of water molecules through a cell membrane from an area of higher water molecule concentration to an area of lower concentration Quick Fact! Quick Fact! Process of osmosis was first described in 1748 by French scientist Abbé Jean Antoine Nollet. He observed that water spontaneously diffused through a pig bladder membrane into alcohol! Process of osmosis was first described in 1748 by French scientist Abbé Jean Antoine Nollet. He observed that water spontaneously diffused through a pig bladder membrane into alcohol!

16. Direction of Osmosis Depends upon the relative concentration of solutes on the two sides of the membrane Depends upon the relative concentration of solutes on the two sides of the membrane

17. Osmotic Potential The tendency of water to move across a membrane into a solution The tendency of water to move across a membrane into a solution The lower the solute concentration, the higher the osmotic potential The lower the solute concentration, the higher the osmotic potential

18. Isotonic Solution A solution in which the concentration of dissolved substances is the same as the concentration inside the cell; therefore, the concentration of water is the same on both sides of the plasma membrane A solution in which the concentration of dissolved substances is the same as the concentration inside the cell; therefore, the concentration of water is the same on both sides of the plasma membrane Diffusion of water in = water out Diffusion of water in = water out

19. Turgor Pressure Pressure that exists inside a cell Pressure that exists inside a cell

20. Hypotonic Solution A solution in which the concentration of a dissolved substance is lower than the concentration inside the cell; therefore, the concentration of water is greater outside the cell than inside the cell A solution in which the concentration of a dissolved substance is lower than the concentration inside the cell; therefore, the concentration of water is greater outside the cell than inside the cell Water diffuses into the cell & the cell swells-Turgor Pressure increases Water diffuses into the cell & the cell swells-Turgor Pressure increases Cytolysis – cell bursts Cytolysis – cell bursts Plant v. Animal Plant v. Animal

21. Osmosis (Cell in Hypotonic Solution

22. Hypertonic Solution A solution in which the concentration of dissolved substances is higher than the concentration inside the cell; the concentration of water is greater in the cell than outside A solution in which the concentration of dissolved substances is higher than the concentration inside the cell; the concentration of water is greater in the cell than outside Result: water moves out of the cell & the turgor pressure decreases & the cell shrivels Result: water moves out of the cell & the turgor pressure decreases & the cell shrivels Plasmolysis – loss of water pressure in a cell Plasmolysis – loss of water pressure in a cell

23. Osmosis (Cell in Hypertonic Environment)

24. Click for animation

25. How Cells Deal with Osmosis Example: Paramecia (freshwater protozoan) Example: Paramecia (freshwater protozoan) Live in a hypotonic environment Live in a hypotonic environment Water constantly diffuse into them Water constantly diffuse into them Contractile vacuoles (organelle) removes the excess water Contractile vacuoles (organelle) removes the excess water A common remedy for a sore throat is to gargle with salt water. Using the concept of osmosis, explain how this remedy might work. A common remedy for a sore throat is to gargle with salt water. Using the concept of osmosis, explain how this remedy might work. Quick Fact! Quick Fact! Wooden drawers in cabinets absorb water from the air on humid days causing the wood to swell & hard to open! Wooden drawers in cabinets absorb water from the air on humid days causing the wood to swell & hard to open!

26. Osmotic Pressure Pressure required to stop osmosis in a solution Pressure required to stop osmosis in a solution - Pressure that builds up as water diffuses into a cell - If a physical barrier prevents expansion of a hypertonic solution as water moves in by osmosis, a buildup of pressure is created as water continues to flow in - As pressure ↑, the net flow of water molecules will slow (stops in plants due to cell wall – turgor pressure)

27. Reverse Osmosis The movement of water particles from an area of lower concentration to an area of higher concentration with the Addition of pressure

28. Facilitated Diffusion Used for molecules that cannot diffuse rapidly across the membrane (size, polarity) Used for molecules that cannot diffuse rapidly across the membrane (size, polarity) Molecules are assisted by membrane proteins Molecules are assisted by membrane proteins 2 Types 2 Types Carriers & Channels Carriers & Channels Move down the concentration gradient (High [ ] to low [ ]) no energy is used by cell Move down the concentration gradient (High [ ] to low [ ]) no energy is used by cell

29. Facilitated Diffusion Molecule binds to carrier protein Molecule binds to carrier protein Protein changes shape shielding molecule from lipids as it crosses Protein changes shape shielding molecule from lipids as it crosses Molecule is released to cell interior Molecule is released to cell interior Carrier protein returns to original shape Carrier protein returns to original shape Accelerates glucose movement Accelerates glucose movement Carrier proteins are specific to the molecules they carry Carrier proteins are specific to the molecules they carry

30. Facilitated Diffusion CarriersChannels

31. Diffusion through Ion Channels Membrane proteins Membrane proteins Passageway through membrane for ions to pass through (Na+, Ca2+, Cl-) Passageway through membrane for ions to pass through (Na+, Ca2+, Cl-) Each ion channel is specific to one type of ion Each ion channel is specific to one type of ion Some channels are always open, others have gates Some channels are always open, others have gates Gates open in response to stimuli Gates open in response to stimuli 1. Stretching of cell membrane 2. Electrical signals 3. Chemical signals

32. Ion Channels

33. Active Transport Differentiate between active & passive transport Differentiate between active & passive transport Compare & contrast endocytosis & exocytosis Compare & contrast endocytosis & exocytosis

34. Active Transport Movement of materials up a concentration gradient, from an area of low concentration to an area of higher concentration Movement of materials up a concentration gradient, from an area of low concentration to an area of higher concentration Requires cell to use energy Requires cell to use energy Uses carrier proteins Uses carrier proteins [ ] = Concentration [ ] = Concentration

35. Active Transport Endocytosis & Exocytosis Endocytosis & Exocytosis Transport of macromolecules & food particles too large to pass to pass through cell membrane Transport of macromolecules & food particles too large to pass to pass through cell membrane

36. Endocytosis Process by which cells ingest large materials by surrounding them with the cell membrane forming a pouch Process by which cells ingest large materials by surrounding them with the cell membrane forming a pouch Pouch pinches off from membrane & forms a vesicle Pouch pinches off from membrane & forms a vesicle

37. Endocytosis Types: Types: Pinocytosis Pinocytosis Transports solutes or fluids (cell drinking) Transports solutes or fluids (cell drinking)

38. Endocytosis Phagocytosis Phagocytosis Ingestion large particles or whole cells (cell eating) Ingestion large particles or whole cells (cell eating) Many unicellular organisms feed this way Many unicellular organisms feed this way Used to ingest bacteria & viruses Used to ingest bacteria & viruses Cells called phagocytes – allows lysosomes to fuse with vesicles containing bacteria & viruses to destroy them Cells called phagocytes – allows lysosomes to fuse with vesicles containing bacteria & viruses to destroy them

39. Exocytosis Reverse of endocytosis Reverse of endocytosis Cell excretion Cell excretion Vesicles in cytoplasm fuse with cell membrane to release contents to external environment Vesicles in cytoplasm fuse with cell membrane to release contents to external environment Releases proteins packaged in Golgi apparatus Releases proteins packaged in Golgi apparatus

40. ENDOCYTOSIS/EXOCYTOSIS

41. Kidspiration by: Riedell