1. End Show Slide 1 of 47 Copyright Pearson Prentice Hall 7-3 Cell Boundaries

2. End Show Slide 2 of 47 7-3 Cell Boundaries All cells are surrounded by a thin, flexible barrier known as the cell membrane. Many cells also produce a strong supporting layer around the membrane known as a cell wall. Copyright Pearson Prentice Hall

3. End Show 7-3 Cell Boundaries Slide 3 of 47 Cell Membrane The cell membrane regulates what enters and leaves the cell and also provides protection and support. Copyright Pearson Prentice Hall Cell Membrane

4. End Show Slide 4 of 47 Cell Membrane Copyright Pearson Prentice Hall Outside of cell Cell membrane Inside of cell (cytoplasm) Protein channel Proteins Lipid bilayer Carbohydrate chains

5. End Show 7-3 Cell Boundaries Slide 5 of 47 Copyright Pearson Prentice Hall Cell Walls What is the main function of the cell wall?

6. 7-3 Cell Boundaries Slide 6 of 47 Cell Walls Copyright Pearson Prentice Hall Cell Wall Cell walls are found in plants, algae, fungi, and many prokaryotes.

7. 7-3 Cell Boundaries Slide 7 of 47 Copyright Pearson Prentice Hall Diffusion Through Cell Boundaries Measuring Concentration A solution is a mixture of two or more substances. The substances dissolved in the solution are called solutes. The concentration of a solution is the mass of solute in a given volume of solution, or mass/volume.

8. End Show 7-3 Cell Boundaries Slide 8 of 47 Copyright Pearson Prentice Hall Diffusion Through Cell Boundaries What happens during diffusion?

9. 7-3 Cell Boundaries Slide 9 of 47 Copyright Pearson Prentice Hall Diffusion Through Cell Boundaries Diffusion Particles in a solution tend to move from an area where they are more concentrated to an area where they are less concentrated. This process is called diffusion. When the concentration of the solute is the same throughout a system, the system has reached equilibrium.

10. End Show Slide 10 of 47 Diffusion Through Cell Boundaries Copyright Pearson Prentice Hall

11. End Show Slide 11 of 47 Copyright Pearson Prentice Hall

12. End Show 7-3 Cell Boundaries Slide 12 of 47 Copyright Pearson Prentice Hall Osmosis What is osmosis?

13. 7-3 Cell Boundaries Copyright Pearson Prentice Hall Osmosis Osmosis is the diffusion of water through a selectively permeable membrane.

14. End Show Slide 14 of 47 Osmosis How Osmosis Works Copyright Pearson Prentice Hall Movement of water Dilute sugar solution (Water more concentrated) Concentrated sugar solution (Water less concentrated) Sugar molecules Selectively permeable membrane

15. End Show Slide 15 of 47 Water tends to diffuse from a highly concentrated region to a less concentrated region. If you compare two solutions, three terms can be used to describe the concentrations: Hypertonic– surrounding solution is MORE concentrated than interior of cell – water moves out of the cell. hypotonic - surrounding solution is LESS concentrated than interior of cell – water moves into of the cell isotonic - surrounding solution is EQUALLY concentrated to the interior of cell – Water moves both in and out but no net gain or loss Copyright Pearson Prentice Hall

16. End Show Slide 16 of 47 16 Osmosis Diffusion of water across a membraneDiffusion of water across a membrane Moves from HIGH water potential (low solute) to LOW water potential (high solute)Moves from HIGH water potential (low solute) to LOW water potential (high solute) Diffusion across a membrane Semipermeable membrane

17. 7-3 Cell Boundaries Slide 17 of 47 Copyright Pearson Prentice Hall Osmosis Osmotic Pressure Osmosis exerts a pressure known as osmotic pressure on the hypertonic side of a selectively permeable membrane.

18. 7-3 Cell Boundaries Slide 18 of 47 18 Cell in Isotonic Solution CELL 10% NaCL 90% H 2 O 10% NaCL 90% H 2 O What is the direction of water movement? The cell is at _______________. equilibrium ENVIRONMENT NO NET MOVEMEN T

19. 7-3 Cell Boundaries Slide 19 of 47 19 Cell in Hypotonic Solution CELL 10% NaCL 90% H 2 O 20% NaCL 80% H 2 O What is the direction of water movement?

20. 7-3 Cell Boundaries Slide 20 of 47 20 Cell in Hypertonic Solution CELL 15% NaCL 85% H 2 O 5% NaCL 95% H 2 O What is the direction of water movement? ENVIRONMENT

21. 7-3 Cell Boundaries Slide 21 of 47 21 Cells in Solutions

22. 7-3 Cell Boundaries Slide 22 of 47 22 Isotonic Solution NO NET MOVEMENT OF H 2 O (equal amounts entering & leaving) Hypotonic Solution CYTOLYSIS Hypertonic Solution PLASMOLYSIS

23. 7-3 Cell Boundaries Slide 23 of 47 23 Cytolysis & Plasmolysis Cytolysis Plasmolysis

24. 7-3 Cell Boundaries Slide 24 of 47 24 Osmosis in Red Blood Cells Isotonic Hypotonic Hypertonic

25. 7-3 Cell Boundaries Slide 25 of 47 25 hypotonic hypertonicisotonic hypertonicisotonichypotonic

26. 26 Types of Transport Proteins Channel proteins are embedded in the cell membrane & have a pore for materials to cross Carrier proteins can change shape to move material from one side of the membrane to the other

27. 27 Facilitated Diffusion Molecules will randomly move through the pores in Channel Proteins.

28. 28 Facilitated Diffusion Some Carrier proteins do not extend through the membrane.Some Carrier proteins do not extend through the membrane. They bond and drag molecules through the lipid bilayer and release them on the opposite side.They bond and drag molecules through the lipid bilayer and release them on the opposite side.

29. 29 Carrier Proteins Other carrier proteins change shape to move materials across the cell membraneOther carrier proteins change shape to move materials across the cell membrane

30. 7-3 Cell Boundaries Slide 30 of 47 Copyright Pearson Prentice Hall Active Transport Sometimes cells move materials in the opposite direction from which the materials would normally move—that is against a concentration difference. This process is known as active transport. Active transport requires energy.

31. 7-3 Cell Boundaries Slide 31 of 47 Copyright Pearson Prentice Hall Active Transport Molecular Transport In active transport, small molecules and ions are carried across membranes by proteins in the membrane. Energy use in these systems enables cells to concentrate substances in a particular location, even when diffusion might move them in the opposite direction.

32. End Show Slide 32 of 47 Active Transport Copyright Pearson Prentice Hall Molecule to be carried Molecular Transport

33. 33 Active Transport Requires energy or ATP Moves materials from LOW to HIGH concentration AGAINST concentration gradient

34. 34 Active transport  Examples: Pumping Na + (sodium ions) out and K + (potassium ions) in against strong concentration gradients.  Called Na+-K+ Pump

35. 35 Sodium-Potassium Pump 3 Na+ pumped in for every 2 K+ pumped out; creates a membrane potential

36. 7-3 Cell Boundaries Slide 36 of 47 Copyright Pearson Prentice Hall Active Transport Endocytosis and Exocytosis Endocytosis is the process of taking material into the cell. Two examples of endocytosis are: phagocytosis pinocytosis During exocytosis, materials are forced out of the cell.

37. 37 Pinocytosis Cell forms an invaginationCell forms an invagination Materials dissolve in water to be brought into cellMaterials dissolve in water to be brought into cell Called “Cell Drinking”Called “Cell Drinking”

38. 38 Phagocytosis Phagocytosis - Capture of a Yeast Cell (yellow) by Membrane Extensions of an Immune System Cell (blue)

39. 39 Inside Cell Cell environmentExocytosis The opposite of endocytosis is exocytosis. Large molecules that are manufactured in the cell are released through the cell membrane.

40. End Show - or - Continue to: Click to Launch: Slide 40 of 47 Copyright Pearson Prentice Hall 7-3

41. End Show Slide 41 of 47 Copyright Pearson Prentice Hall 7-3 Unlike a cell wall, a cell membrane a.is composed of a lipid bilayer. b.provides rigid support for the surrounding cell. c.allows most small molecules and ions to pass through easily. d.is found only in plants, fungi, algae, and many prokaryotes.

42. End Show Slide 42 of 47 Copyright Pearson Prentice Hall 7-3 The concentration of a solution is defined as the a.volume of solute in a given mass of solution. b.mass of solute in a given volume of solution. c.mass of solution in a given volume of solute. d.volume of solution in a given mass of solute.

43. End Show Slide 43 of 47 Copyright Pearson Prentice Hall 7-3 If a substance is more highly concentrated outside the cell than inside the cell and the substance can move through the cell membrane, the substance will a.move by diffusion from inside the cell to outside. b.remain in high concentration outside the cell. c.move by diffusion from outside to inside the cell. d.cause water to enter the cell by osmosis.

44. End Show Slide 44 of 47 Copyright Pearson Prentice Hall 7-3 The movement of materials in a cell against a concentration difference is called a.facilitated diffusion. b.active transport. c.osmosis. d.diffusion.

45. End Show Slide 45 of 47 Copyright Pearson Prentice Hall 7-3 The process by which molecules diffuse across a membrane through protein channels is called a.active transport. b.endocytosis. c.facilitated diffusion. d.osmosis.