TRANSPORT IN CELLS

1. TRANSPORT IN CELLS

2. Cell Membrane • Once believed to be a covering like a balloon. • “Gate keeper” allows materials in and out while maintaining the integrity of the cell. • Actually composed of many different molecules

3. Phospholipids Main structural component of cell membrane

4. Proteins Proteins embedded in membrane aid in the transport of large molecules and energy.

5. Carbohydrates Function to help cells recognize other cells, hold proteins in place and provide energy for repair

6. Fluid Mosaic Model All the molecules of the cell membrane are in constant motion. What benefit does the motion serve? http://www.dnatube.com/video/360/Fluid-Mosaic-Model

7. Cell Size is related to transport. If the surface area to volume increases to much then materials will not be able to move in or out fast enough. A small cell is a more efficient cell.

8. PASSIVE TRANSPORT MOVEMENT OF MOLECULES INTO OR OUT OF A CELL WITHOUT THE CELL USING ANY ENERGY MOLECULES MOVE DUE TO THEIR OWN KINETIC ENERGY AS LONG AS THERE IS A CONCENTRATION GRADIENT PRESENT

9. DIFFUSION Movement of any molecule from an area of greater concentration to an area of lesser concentration down a concentration gradient toward equilibrium.

10. Important Points… • All states of matter can diffuse. • solids, liquids, gases • Diffusion can take place across a membrane • O2 and CO2 diffuse across cell membrane • Factors that affect rate of diffusion • Heat: warm materials diffuse faster • Motion: stirring or shaking increases diffusion • Surface area: greater surface area faster diffusion • Volume: smaller space faster diffusion

11. http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__how_diffusion_works.htmlhttp://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__how_diffusion_works.html

12. FACILITATED DIFFUSION Transport of molecules across a membrane with the help of cell membrane proteins. Since the molecules are still moving down a concentration gradient, no energy is required. WHAT MOLECULES NEED HELP? Polar molecules and ionsare diffused across by channel proteins. WHY? Because they are polar and dissolve in water and can’t get past the hydrophobic ends of the membrane. Large molecules like amino acids and glucose are diffused across with the help of carrier proteins.

14. OSMOSIS Very similar to diffusion with two exceptions: MOVEMENT OF WATER ACROSS A SEMI-PERMEABLE MEMBRANE From an area of greater concentration Down a concentration gradient Toward equilibrium MERMAID

15. The direction the water moves,into or out of the cell… depends upon how much material, or,solute is dissolved in the water!

16. OK, here’s where it can get confusing! Solutions are named based upon the amount of dissolved solute notthe amount of water… even though it’s the water that’s moving!

17. HYPOTONIC: LOW SOLUTE CONCENTRATION • outsidecell membrane • HIGHWATER CONCENTRATION outside cell membrane • WATER MOVES INTO THE CELL • CAUSING IT TO SWELL, THIS IS • CALLED CYTOLYSIS, IF THE • WATER CANNOTBE • CONTROLLED THE CELL WILL • RUPTURE.FLOWER

18. ISOTONIC: SOLUTE CONCENTRATION IS EQUAL TO WATER CONCENTRATION INSIDE AND OUTSIDE OF CELLWATER MOVES INTO AND OUT OF CELL EQUALLY, NET VOLUME IS MAINTAINED= HOMEOSTASIS

19. HYPERTONIC: HIGH SOLUTE CONCENTRATION outside cell membrane LOWWATER CONCENTRATION outside cell membrane WATER MOVES OUT OF THE CELL CAUSING IT TO SHRIVEL UP, THIS IS CALLED PLASMOLYSIS

20. http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__how_osmosis_works.htmlhttp://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__how_osmosis_works.html

22. OSMOSIS PRACTICE Environment= 75% water Environment= 30% solute Cell = 25% water Cell = 30% solute Water moves__________ Water moves__________ Environment= 40% solute Environment is 10% water Cell = 60% solute Cell = 90% water Water moves__________ Water moves__________