Homeostasis and Transport

1. Homeostasis and Transport Chapter 5

2. What is Homeostasis??

3. QUESTIONS?? • Why is Transport important within your cells?? • What are some things that are transported within you body??

4. I. Passive Transport • Cell membranes help organisms maintain homeostasis by controlling what substances may enter or leave cells • Movement of substances across the membrane that does NOTrequire energy “ Passive Transport” • Movement is based on the presence of a concentration gradient

5. Concentration gradient • Difference in concentrations of the substances. • Ratio of solute to solvent • No net movement when there is equilibrium • A condition where the gradient disappears

8. A. Diffusion • The process by which substances move from an area of high solute concentration to an area of lower solute concentration • Diffusion is the simplest type of passive transport • Driven entirely by the kinetic energy the molecules possess • Molecules tend to move “down” their concentration gradient from (high to low conc.)

10. Diffusion • Cell membranes have the ability to control what passes through them • The ability of a molecule to go through a membrane depends on….. • 1. The size of the molecule. Molecules can be polar and still move through lipids because they are very small • 2. The type of molecule. Can it dissolve in lipids? • Ex: CO2 and O2 can dissolve in lipids. Why? • 3. The molecular structure of the membrane

20. B. Osmosis • The movement of water from an area of high water concentration to an area of low water concentration • Another way to say this is… • The movement of water from an area of low solute concentration to an area of high solute concentration

21. Direction of Osmosis • The net direction of water molecule movement is dependent upon… • Concentrations of water • Solutes dissolved in the solution

22. Pics

23. 3 Types of Solutions • 1. HYPOTONIC: • Outside Cell: low solute, high solvent • Inside Cell: high solute, low solvent • Effect on Cell: Cell will Swell

25. HYPERTONIC: • Outside Cell: high solute, low solvent • Inside Cell: low solute, high solvent • Effects on cell: Cell will shrink

27. ISOTONIC: • Outside Cell: same solute and solvent • Inside Cell: same solute and solvent • Effects on Cell: stays the same

29. pic

31. The blood cells are shriveling up because the water is leaving the cell. The cells are normal because the water stays in the cell.

33. Turgor Pressure - The pressure exerted by water inside the cell against the cell wall. • Pic

34. Role of Osmosis • The net movement of water into a cell can cause Turgor Pressure • When turgor pressure is too high or the cell takes in too much water the cell can swell But wont “burst” • WHY?? • When turgor pressure is lost, the plant wilts-Plasmolysis

35. Some organisms live in a hypotonic environment ---Why is this bad for a single celled organism?? • Contractile Vacuoles • Specialized organs remove excess water

36. D. Facilitated Diffusion • Uses Carrier Proteins • Specific to what they will transport across the cell membrane • No energy required (Passive process) • Speeds up diffusion

37. Facilitated Diffusion

38. C. Ion Channels • Transport proteins that allow ions to pass through the cell membrane • Channels are either Open or Closed • Closed channels will respond to different stimuli to allow things to pass through them

39. PIC

40. Examples of Passive Transport • PIC

41. II. Active Transport • The movement of any substances across a cell membrane that does require energy • Active Transport Vid

42. A. Sodium Potassium Pump • Movement of Sodium and Potassium against the concentration gradient • Uses ATP as energy source • Important for many vital functions: • 1. Muscle contractions • 2. Nerve impulses • 3. Kidney function

43. Sodium/Potassium Pump. Na+/K+ Pump

44. B. Endocytosis and Exocytosis • Processes used for moving substances across a membrane that are too large to pass through a channel • 1. Endocytosis: • Process by which cells take in large particles. Ex: external fluid, macromolecules, and other cells • A. Phagocytosis: - food particles or microscopic organisms • B. Pinocytosis:- solutes or fluids

46. 2. Exocytosis: • Process that removes large waste products from the cell and large molecules such as proteins. • What organelle produces the vesicles that will eventually fuse with the cell membrane and release its contents?

47. Endocytosis and Exocytosis

48. Formation of vesicles

49. III. Receptor Proteins • A protein that binds to a specific signal molecule • Enables the cell to respond to the signal molecule • The binding of a signal molecule to the receptor protein causes changes in the receiving cell in three ways…..