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- 1. Cellular Transport ‘07 Biology
- 2. 2 Types: Active Passive Energy! No energy!
- 3. Passive Transport Substances areallowed to cross the cell membrane without any input of energy Remember: The cell membrane is “selectively permeable” QuickTimeª and a TIFF (Uncompressed) decompressor are needed to see this picture.
- 4. Types of PassiveTransport Diffusion Facilitated Diffusion Osmosis
- 5. Diffusion Movement of moleculesfrom areas of high concentration to low How does it work? “Kinetic energy” (energy in motion) Concentration gradient- caused by a difference in concentration Diffusion results in equilibrium (all molecules occupy the same amount of space)
- 6. Facilitated Diffusion Some moleculesare helped across the cell membrane by carrier proteins No energy is required in this process QuickTimeª and a TIFF (Uncompressed) decompressor are needed to see this picture.
- 7. Osmosis The diffusion ofwater across the cell membrane The direction of osmosis depends on the concentration of solutes inside and outside the cell
- 8. Osmosis (continued) Hypotonic- concentrationof solutes outside the cell is lower than the concentration inside Hypertonic- concentration outside is higher than inside Isotonic- concentrations inside and out are equal
- 9. Direction of Osmosis QuickTimeª and a TIFF (Uncompressed) decompressor are needed to see this picture.
- 10. Active Transport Sometimes cellsmust move molecules against the concentration gradient This process requires energy (ATP) and special protein “pumps”
- 11. Sodium-Potassium Pump Special proteinswithin the membrane that transport Na+ and K- ions Some cells must have a higher concentration of Na+ ions outside of the cell and a higher concentration of K- ions inside the cell 2 Potassiums are brought in for every 3 Sodiums removed
- 12. Sodium-Potassium Pump QuickTimeª and a TIFF (Uncompressed) decompressor are needed to see this picture.
- 13. Movement In Vesicles Somemolecules are too big to be transported across the cell membrane by passive and active transport Endocytosis- “cell eating” Exocytosis- “cell pooping”
- 14. Endocytosis Process by whichcells ingest macromolecules, fluids, large particles and even other cells These molecules are enclose in a bubble of membrane (vesicle) that pinches away from the cell membrane
- 15. Endocytosis (continued) Pinocytosis- ingestionof small particles and fluid Phagocytosis- ingestion of large molecules or other cells QuickTimeª and a TIFF (Uncompressed) decompressor are needed to see this picture.
- 16. Exocytosis Process by whichwaste and large particles are released from the cell A vesicle will fuse with the membrane, releasing its contents into the extra cellular environment
- 17. Endocytosis/Exocytosis QuickTimeª and a TIFF (Uncompressed) decompressor are needed to see this picture.
Editor's Notes
- #2 What is meant by the word transport? Moving substances across the cell membrane
- #4 What is the cell membrane made of? Lipids make it polar--> oxygen and co2 can readily pass through Small molecules can pass through protein pores
- #6 Spray aerosol into the corner of the classroom Kinetic energy --> Particles are constantly moving and bumping into each other Start a mosh pit in the corner of the classroom In the absence of outside influence diffusion will continue until equilibrium is reached
- #7 Molecules may be too large or not soluble in lipids --> glucose
- #10 Hypotonic solutions are good Cells adapt by pumping water or solutes out of the cytosol (contractile vacuoles or solute pumps) Plants love hypotonic environments --> turgor pressure Hypertonic solutions are bad…emkay Results in the loss of water --> plasmolysis Some cells cannot adjust to changes in environment (rbc’s) --> cytolysis or “cell bursting “ may result
- #14 Macromolecules, nutrients, large quantities of small molecules
- #15 The vesicles then fuse with other membrane bound organelles within the cell
- #16 Phagocytosis can be used to ingest bacteria or viruses that invade the body! Pic --> white blood cell ingestng bacteria