2. 1 Movement Across Membranes

3. 2 1. Diffusion

4. 3 DiffusionDiffusion Particles in liquids and gases move in random directions with a certain amount of kinetic energy

5. 4 DiffusionDiffusion The overall effect of this is that particles become evenly distributed in their container

6. 5 DiffusionDiffusion Kinetic Energy can be increased by increasing the temperature

7. 6 Examples: Diffusion of CO 2 into stomata of leaves during photosynthesis. Diffusion of CO 2 into stomata of leaves during photosynthesis. Diffusion of O 2 into the alveoli of the lungs Diffusion of O 2 into the alveoli of the lungs Diffusion of O 2 to respiring cells Diffusion of O 2 to respiring cells Diffusion of glucose, amino acids etc. into the villi during digestion. Diffusion of glucose, amino acids etc. into the villi during digestion.

8. 7 2. Osmosis The cell membrane is partially permeable permeable – it allows small, particles to pass through by simple diffusion

9. 8 The cell membrane is partially permeable – it allows small, uncharged or high energy particles to pass through by simple diffusion

10. 9 Osmosis is simply a special case of diffusion… Osmosis is simply a special case of diffusion… …that applies to WATER …that applies to WATER

11. 10

12. 11

13. 12

14. 13 Water Potential ‘Water potential’ is a measure of the amount of kinetic (movement) energy water molecules have

15. 14 Water Potential Water potential (  ) is a measure of the amount of kinetic energy water molecules have

16. 15 Water Potential In pure water at STP, the molecules are given a water potential of 0

17. 16 “Osmosis is the diffusion of water molecules from areas of high water potential to areas of lower water potential through a partially permeable membrane” OsmosisOsmosis

18. 17 Osmosis is the diffusion of water molecules from areas of high water potential to areas of lower water potential through a partially permeable membrane. OsmosisOsmosis

19. 18 Osmosis and Animal Cells Cells placed in a solution of higher water potential

20. 19 Osmosis and Animal Cells Cells placed in a solution of higher water potential Water enters by osmosis Cell bursts (lysis)

21. 20 Osmosis and Animal Cells Cells placed in a solution of lower water potential

22. 21 Osmosis and Animal Cells Cells placed in a solution of lower water potential Water leaves by osmosis Cell shrivels (crenation)

23. 22 Osmosis and Plant Cells Cells placed in a solution of higher water potential

24. 23 Osmosis and Plant Cells Cells placed in a solution of higher water potential Water enters by osmosis Cell becomes TURGID

25. 24 Osmosis and Plant Cells Cells placed in a solution of lower water potential

26. 25 Osmosis and Plant Cells Cells placed in a solution of lower water potential Water leaves by osmosis Cell shrivels (PLASMOLYSED)

27. 26 Osmosis and Plant Cells These cells are placed in strong sugar solution – would they become turgid or plasmolysed? plasmolysed

28. 27 When plant cells lose water and plasmolyse… When plant cells lose water and plasmolyse… …the plant is unable to support itself and starts to WILT. …the plant is unable to support itself and starts to WILT.

29. 28 Osmosis and Plant Cells And when turgid turgid the cell contents exert outward pressure on the cell wall This helps to support support plants and keep them upright.

30. 29 Osmosis and Plant Cells

31. 30

32. 31 Active Transport Active transport moves substances against against a concentration gradient.

33. 32 Active Transport Movement involves the hydrolysis of ATP to supply energy

34. 33 Active Transport Structural changes in the carrier proteins result in the movement of material

35. What is active transport? What is active transport? Movement of substances in and out of cells by diffusion involves molecules moving down a concentration gradient from high to low concentration. Sometimes substances move into cells from low to high concentration. This is called active transport. Active transport needs energy to make it happen. How do molecules move along the concentration gradient during active transport? high concentration low concentration diffusion active transport

36. Active transport and plants Active transport and plants Plants need mineral elements from the soil for healthy growth. Minerals enter a plant though its roots. The concentration of minerals in the soil is lower than that inside a root hair cell, so how do minerals enter the root cell? soil mineral element root hair cell

37. Active transport and plants Active transport and plants Minerals enter a root cell by active transport. The plant uses energy to move minerals up the concentration gradient from the soil into its root cells. Why is it important for plants to use energy in this way? soil mineral element root hair cell active transport

38. 37 Summary: Active Transport is: Active Transport is: “The movement of molecules AGAINST their concentration gradient, using ENERGY from respiration.” “The movement of molecules AGAINST their concentration gradient, using ENERGY from respiration.” In mammals, nerves and brain cells carry out Active Transport and use 1/3 of all the energy in your body! In mammals, nerves and brain cells carry out Active Transport and use 1/3 of all the energy in your body!

39. 38 So you could get fit just by thinking about it!!

40. Salt Glands in marine animals 39

41. 40 Why is Cyanide such an effective poison? Murder: Murder: Gregor Rasputin Gregor Rasputin Nazi gas Chambers (Zyklon B) Nazi gas Chambers (Zyklon B) Irwin Rommell Irwin Rommell Eva Braun Eva Braun Hermann Goering Hermann Goering

42. 41 Why is Cyanide such an effective poison? Suicide: Suicide: Adolf Hitler Adolf Hitler Irwin Rommell Irwin Rommell Hermann Goering Hermann Goering Heinrich Himmler Heinrich Himmler Eva Braun Eva Braun Alan Turing Alan Turing Tamil Tigers Tamil Tigers

43. What is Cyanide? Hydrogen Cyanide ( HCN) Hydrogen Cyanide ( HCN) Found naturally in apple pips, apricot, cherry and peach stones, clover leaves, elderberrys Found naturally in apple pips, apricot, cherry and peach stones, clover leaves, elderberrys Component of cigarette smoke Component of cigarette smoke 42

44. How does it kill? Destroys the final enzyme in the respiration chain ( in mitochondria) Destroys the final enzyme in the respiration chain ( in mitochondria) Without ATP energy, active transport cannot occur Without ATP energy, active transport cannot occur Without aerobic respiration, brain and heart cells die in 30 seconds. Without aerobic respiration, brain and heart cells die in 30 seconds. 43

45. Jonestown Religious Cult – Mass suicide. 900 dead. 44

46. Concentrations of ions in a plant cell Fresh water K + 0.1 K + 0.1 Cl - 1.3 Cl - 1.3 cell membranecytoplasmcell wall vacuole cell membranecytoplasmcell wall vacuole 45 120 65 75 106

47. Compare the ways potassium and chloride ions a) enter the cytoplasm from the water (2) b) pass from the cytoplasm into the vacuole (2) Fresh water K + 0.1 K + 0.1 Cl - 1.3 Cl - 1.3 cell membranecytoplasmcell wall vacuole cell membranecytoplasmcell wall vacuole 46 120 65 75 106