Cells and Their Environment

1. Cells and Their Environment Chapter 4 p 74-84

2. Homeostasis • A biological balance • Cells, tissues, organs, and organisms must maintain a balance. • Cells do so by controlling and regulating what gets into and out of the cell.

4. Active The movement of any substance across a cell membrane with the use of chemical energy ie: Na+/K+ pump Passive Transport that does not require chemical energy to occur ie: diffusion and osmosis Transport

5. DIFFUSION • Process by which molecules spread from an area of high concentration to an area of low concentration • Concentration gradient: a difference in the concentration of a substance • Examples: • Oxygen diffusing into cells • Beaker of water with food coloring • Smell of perfume in a room ***Molecules are in constant motion

6. Diffusion animations • http://www.northland.cc.mn.us/biology/Biology1111/animations/transport1.html • http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__how_diffusion_works.html

7. Osmosis • Diffusion of water through a membrane from an area of high concentration to an area of low concentration. What determines the direction in which water molecules diffusion across a cell membrane? **the concentration of water and of solutes dissolved in the solution

8. http://www.stolaf.edu/people/giannini/flashanimat/transport/osmosis.swfhttp://www.stolaf.edu/people/giannini/flashanimat/transport/osmosis.swf • http://www.tvdsb.on.ca/westmin/science/sbi3a1/Cells/Osmosis.htm • http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__how_osmosis_works.html • http://www.wiley.com/legacy/college/boyer/0470003790/animations/membrane_transport/membrane_transport.htm

9. Think about it… What happened if you eat salty foods? Grass wilts if you add too much fertilizer…WHY?

10. Cells can be found in 1 of 3 solutions: • HypOtonic 2. Hypertonic 3. Isotonic

11. HYPOTONIC • Concentration of solute molecules in the environment outside of the cell is lower than that in the cell. • Water moves in

12. Red blood cell

13. Hypertonic • Concentration of solute molecules outside the cell is greater than that in the cell • Water moves out

14. Isotonic Concentration of solute molecules outside cell and inside are equal. **equilibrium

16. Facilitated diffusion • Use of carrier to “help” move molecules across a membrane • Passive: energy Y or N? • Gradient: H to L • Example: glucose

17. Filtration • Type of Transport: Passive • Using pressure to push something through the cell membrane • Energy needed?? • Example…what organ in your body filters

18. Active transport • Movement of substances through a membrane from a low to high concentration with the use of energy. • ATP: energy form • Usually Low to high concentration • “Against a gradient” • Example: Na/K pump.

19. Active Transport • http://www.brookscole.com/chemistry_d/templates/student_resources/shared_resources/animations/ion_pump/ionpump.html

20. Some molecules are too large to pass thru membrane!!! Even with use of energy • Endocytosis…movement of substances into the cell by transport vesicles into the cell. • Exocytosis… movement of substances outside of the cell by transport vesicles into the cell

21. Endocytosis

22. Exocytosis

23. http://www.coolschool.ca/lor/BI12/unit4/U04L05.htm http://www.wiley.com/college/boyer/0470003790/animations/membrane_transport/membrane_transport.htm http://www.teachersdomain.org/asset/tdc02_int_membraneweb/