Cellular Transport

1. Cellular Transport -movement across the cell membrane

2. Can you die from drinking too much water? • YES. Sadly, a young woman died from participating in a radio contest called “Wee for a Wii”. • When you drink excessive amounts of water, the kidneys cannot process it quickly enough to keep the body’s water/salt concentration balanced, so it moves from the bloodstream into cells by the process of OSMOSIS. • Animal cells swell as water enters. Most cells have room for this, but not nerve cells that make up the brain. This swelling of brain tissue is what ultimately causes death.

3. Are my cells alive? • Cells are the basic unit of structure and function in living organisms

4. All living things are made of cells • Unicellularorganisms are made of one cell • Ex. Bacteria • Multicellularorganisms are made of many, many, many cells • Ex. YOU!

5. All life processes occur at a cellular level • In a multicellular organism, many of the bodily functions (breathing and eating) are necessary to supply individual cells with things the cell needs

6. All life processes occur at a cellular level • The interactions of all the individual cells in a multicellular create a need for other bodily functions (excreting wastes).

7. Cells must interact with their environment to maintain homeostasis • In order for a cell to gain nutrients, the nutrients must be delivered to the cell (ex. by blood) or taken directly from the environment

8. Cell membrane • Cell membrane is the main structure associated with HOMEOSTASIS in the cell • Regulates water concentration and other material • Controls what goes into and out of the cell • Many cells also have CELL WALLS- with large pores, mainly used for support

9. Cells must interact with their environment to maintain homeostasis • In order for some cells to generate energy, they require oxygen. Therefore, this oxygen must be delivered to the cell (ex. by blood) or taken directly from the environment.

10. Cells must interact with their environment to maintain homeostasis • Cells affect their environment by releasing wastesinto their surroundings. • Ex. Algae release oxygen into the lake.

11. How do things get into and out of the cell? • All things entering or leaving the cell must pass through the cell membrane

12. How do things get into and out of the cell? • The cell membrane is selectively permeable

13. Membranes contain structures that allow movement • The membrane contains pores(holes) that allow very small molecules that move in and out freely

14. Membranes contain structures that allow movement • The membrane also contains transport proteins that are specifically shaped to allow essential molecules, such as water, into and out of the cell

15. Fill It In … Two ways that molecules move through the cell membrane: 1. 2.

16. Concentration Gradient MYP • Concentration Gradient- amount of material in solution • Measured in g/L • Example: 12g of salt in 6L of water • Example: 12g of salt in 4L of water • Which has the higher concentration of solute?

17. Passive Transport • Some types of cell transport DO NOT require energy • This is called passive transport

18. Passive Transport • Molecules are constantly in motion. • The movement of molecules is random.

19. Passive Transport • Diffusion is the term used to describe the movement of molecules from areas of high concentration to areas of lower concentration due to random movement

20. Fill It In … Passive transport is movement of molecules from ______ to _____ concentration.

21. Passive Transport • Diffusion can occur in the air, in water, or across a cell membrane • Ex. A drop of red dye spreads throughout the water • Ex. The smell of burnt popcorn spreads through the house

22. Passive Transport • Concentration gradient is the term used to describe the difference between higher and lower concentration.

23. Something extra … • There are two types of diffusion: • (Simple) diffusion • Movement through the pores • Facilitated diffusion • Movement through the transport proteins

24. Passive Transport • Osmosis is the term used to specifically describe the movement of water across a membrane due to diffusion

25. Fill It In … Differentiate between the terms “diffusion” and “osmosis”: Diffusion - Osmosis -

26. The principles of diffusion (and osmosis) can be used to predictthe response of cells in different environments ….

27. Diffusion Demo BEFORE: Dialysis bag is “selectively permeable” Starch (large molecule) inside bag Iodine (small molecule) in beaker AFTER: Starch (large molecule) still inside bag; did NOT diffuse out Iodine (small molecule) diffused INTO bag – evidence is color change

28. A cell has a conc. of 8.0% carbon dioxide gas and 0.4% oxygen gas. The blood surrounding the cell has an oxygen concentration of 1.2% and a carbon dioxide concentration of 0.1%. What will the cell lose? What will the cell gain? Oxygen 1.2% Carbon dioxide 0.1% An example of diffusion: Oxygen 0.4% Carbon dioxide 0.8%

29. Answer: Oxygen will diffuse into the cell and carbon dioxide will diffuse out of the cell. This is called gas exchange Oxygen 1.2% Carbon dioxide 0.1% An example of diffusion: Oxygen 0.4% Carbon dioxide 0.8%

31. Fill It In … Explain WHY the oxygen and carbon dioxide move as they do …

32. more water A blood cell has the same conc. of water and salt as saline solution. A doctor who failed high school biology and did not listen to the attending nurse used an injection full of distilled water (100% water). What will happen to the blood cells surrounded by the distilled water? Examples of osmosis: less water

33. more water Answer: Water will move into the cell through the porcess of osmosis, causing the cell to swell and possibly burst Examples of osmosis: less water

35. You go to the pet store and purchase a fresh water fish. When you get home and place the fish in a salt water aquarium, the fish dies and you cry out “why?” less water (more salt) Examples of osmosis: x more water Fish Cell

36. Answer: water in the fish’s cells left the cell due to osmosis. The loss of water in the gill cells caused the death. less water (more salt) Examples of osmosis: x more water Fish Cell

38. The point at which the molecules are evenly dispersed is called equilibrium

39. Fill It In … Equilibrium means …

40. Several factors affect the speed at which equilibrium is reached. • These factors include temperature (higher temp speeds up the rate of diffusion) and concentration gradient (steeper gradients speed diffusion)

41. At equilibrium, molecules continue to move but there is no net change in the concentration (distribution) of molecules.

43. Ameoba Sisters- Osmosis

44. Osmotic Pressure MYP • Pressure of water acting on the cell membrane • Animal cell might burst • Plant Damage to the cell wall may occur

45. Example: Penicillin • Penicillin works by inhibiting the enzyme used in bacteria that produces a chemical cross-link in their cell wall (damaging the cell wall • Bacteria can build a resistance to this by making β-lactamase , which defends the bacterial walls by assaulting the β-lactam ring

46. Some types of transport DO require energy. • This is called active transport. • Active transport moves molecules against the concentration gradient (from low conc to high conc)

47. Active Transport MYP • Change protein shape- role in acting as a pump • Used to keep the cell alive • Move Ca+2 K+ and Na+2

48. Fill It In … Active transport is movement of molecules from ______ to ______ concentration

49. Some types of transport DO require energy. • Active transport also moves large molecules into and out of the cell that could not normally cross the cell membrane.

50. Movement into the cell = endocytosis • Movement out of the cell = exocytosis