1. Cell Transport Notes

2. All cells have a cell membrane made of proteins and lipids Cell Membrane lipid bilayer protein channel protein pump Layer 1 Layer 2 Cell Membrane

3. Function of Cell Membrane Cell membrane separates the components of a cell from its environment—surrounds the cell “Gatekeeper” of the cell—regulates the flow of materials into and out of cell—selectively permeable Cell membrane helps cells maintain homeostasis—stable internal balance

4. Cell Membrane Structure

5. Phospholipids Lipids (fatty acid) with a phosphate group attached. Polar head and non-polar tails Hydrophilic (likes water) head and hydrophobic (afraid of water) tail Tail

6. Hydrophilic and Hydrophobic Hydrophilic: “likes water” Hydrophobic: “fears water” - repels water

7. Transport Proteins Found in plasma membrane (also known as transport proteins) Allows larger substances to move through the plasma membrane.

8. Cholesterol molecule Helps stabilize the phospholipids Prevents the fatty acid chains of the phospholipids from sticking together

9. Passive Transport Movement of material down the concentration gradient, requires NO energy from the cell

10. Diffusion…going with the flow Diffusion: The random movement of molecules from an area of high concentration to an area of low concentration.

11. Osmosis Osmosis: The movement of water across a semipermeable membrane due to differences in the solute on each side.

12. Facilitated Diffusion Passive Transport by Proteins (NO energy required) Channel proteins – form channels to allow specific molecules to flow through Carrier proteins – change shape to allow a substance to pass through the membrane. outside of cell inside of cell Glucose molecules

13. Active Transport Movement of material through a membrane against a concentration gradient, requires energy from the cell outside of cell inside of cell Carbon Dioxide molecules

16. Transport of Large Particles 1.Endocytosis – the process by which a cell surrounds and takes in material from its environment. (engulfed) 2.Exocytosis – the expulsion or secretion of materials from a cell.

20. Same Conc. Lower Conc. Higher Conc. Effect of concentration

21. Hypertonic Solutions: contain a high concentration of solute relative to another solution (e.g. the cell's cytoplasm). When a cell is placed in a hypertonic solution, the water diffuses out of the cell, causing the cell to shrivel. Hypotonic Solutions: contain a low concentration of solute relative to another solution (e.g. the cell's cytoplasm). When a cell is placed in a hypotonic solution, the water diffuses into the cell, causing the cell to swell and possibly explode. Isotonic Solutions: contain the same concentration of solute as another solution (e.g. the cell's cytoplasm). When a cell is placed in an isotonic solution, the water diffuses into and out of the cell at the same rate. The fluid that surrounds the body cells is isotonic.

23. HYPOTONIC HYPERTONIC ISOTONIC