1. Cellular Transport

2. Objectives: -Summarize the structure & function of the plasma membrane -Summarize passive transport and the four main types -Summarize active transport and the three main types -Relate cell transport to homeostasis Selectively Permeable Membrane

3. Passive Transport Four types: diffusion osmosis facilitated transport ion channels Common characteristics: -No addition of energy (ATP) required. -molecules move from high concentrations to low concentrations.

4. 1. Diffusion -Simplest type of passive transport. -No energy required -Movement of molecules from a high concentration to a low concentration. -Substances being diffused: lipids, gases, fat-soluble molecules Diffusion

6. 2. Osmosis -Passive transport…no ATP needed -Function: diffusion of water across a selectively permeable membrane, high concentration to low concentration. -Substance being diffused: water Osmosis

10. Cells are subject to Osmosis because they are surrounded by water solutions. 1. Isotonic Solutions- outside concentration = inside concentration.

11. 2. Hypotonic Solutions- Concentration (of sugar) is lower outside than inside the cell. This means water wants to move into the cell. Cells begin to swell and may burst. (cytolysis)

12. 3. Hypertonic Solution- Concentration (of sugar) is higher outside of the cell than inside. Water tends to flow out of the cell causing animal cells to shrivel and plant cells to wilt.

13. *Remember…it’s just water moving!

14. Some cells have developed ways to rid themselves of water. Contractile vacuoles (unicellular orgs.) Turgor Pressure, Plasmolysis, Cytolysis Turgor PressurePlasmolysis Contractile Vacuole

15. 3. Facilitated Diffusion -Passive transport…no ATP needed -Function: transports sugars and amino acids using membrane transport proteins that are specific to the molecules that need to pass. -Common molecules…sugars & amino acids

16. 4. Ion Channels -Passive transport…no ATP needed. -Function: transports ions using membrane transport proteins that are specific to the ions that need to pass. Examples of Ions: Cl - Na + Ca 2+ K +

18. Active Transport Active Transport- movement against a concentration gradient from “low to high”. -requires input of energy (ATP) and membrane transport proteins. 1. Cell Membrane Pumps: Sodium-Potassium Pump (move K inside the cell, move Na outside the cell.) -Used in the human muscular and nervous systems. Active Transport

21. Types of Active Transport: 2. Endocytosis: cell membrane surrounds and takes in material from its environment. -pinocytosis-fluids -phagocytosis-large particles or cells PinocytosisPhagocytosisEndo & Exo 3. Exocytosis: the expulsion or secretion of materials out of a cell. -works with the golgi apparatus in forming vesicles to remove large molecules such as proteins, waste products, and toxins out of the cell.

22. EndocytosisExocytosis