1. Exchange with the environment 4-1 Objective: describe and discuss the movement of materials into and out of the cell for the maintenance of homeostasis (diffusion, osmosis, and active transport 1

2. Why do cells need to maintain homeostasis? *Cells need to maintain stable internal conditions (homeostasis), because of changes in their surroundings especially with changes in substances like O 2, H 2 O, CO 2, & NaCl (salt-sodium chloride). 2

3. What cell part controls what goes in and out of the cell? * The cell membrane controls what materials pass into or out of the cell because it is Semipermeable (define) or selectively permeable =being permeable to only certain molecules and not to all molecules. – it selects which molecules may pass through 3

4. Diffusion and Osmosis Diffusion (define) Materials move from high concentration (lots of particles) to low concentration (few particles) Can be any very small particle 4

5. Osmosis define – This is diffusion but just of water – -depends on the concentration of a solute {a substance dissolved in water} 5

6. http://porpax.bio.miami.edu/~cmaller y/150/memb/c8.7x12.osmosis.jpg Six molecules of sugar on the left to 13 on the right, but each side has the same number of water molecules. The ratio of sugar to water is not equal. The water moved across the membrane so that the ratio of sugar to water is in equilibrium on both sides. 6

7. http://www.biologycorner.com/bio1/diffusion.ht ml# http://www.biologycorner.com/bio1/diffusion.ht ml# http://highered.mcgraw- hill.com/sites/0072495855/student_view0/chapt er2/animation__how_osmosis_works.html http://highered.mcgraw- hill.com/sites/0072495855/student_view0/chapt er2/animation__how_osmosis_works.html This happens in cells because the cell membrane is semipermeable 7

8. * Cells (and entire bodies) must have a way of getting rid of excess water to maintain homeostasis even if the water wants to move into the cell. Cells that take in too much water can burst. 8

9. Virtual lab demo on disk. 9

10. Go to Description 10

11. Hypertonic Solution: Lots of Solute in the water -the concentration of water inside the cell is higher than the concentration outside the cell, so water moves out causing the cell to shrink. Isotonic Solution: Same concentration -the concentration of water is the same both inside and outside the cell (compared to the solute) -so water moves into the cell at the same rate it leaves the cell. Hypotonic solution: very little Solute in the water -the concentration of water inside the cell is lower than the concentration outside the cell, so water will enter the cell causing it to swell or burst. Salt and sugar are common solutes, they are too big to move through the cell membrane. Go to pictures 11

12. 12 In Red Blood cells https://www.msu.edu/~knickerk/webquest/osmosis2.gif

13. Which cell is in a hypertonic solution? Hypotonic? Isotonic? 13

14. What does transport mean? Two types of transport: 1)passive 2) active 14

15. Passive Transport Define NO energy used to move materials Only very tiny particles can move across the membrane by passive transport or diffusion. Ex: O 2, H 2, I 2, H 2 0, CO 2. 15

16. Active Transport define -moves a substance from an area of lower to higher concentration (opposite of the way they would naturally move). *- this can be into or out of the cell depending on what the cell needs to maintain homeostasis. 16

17. Protein channels (define) = passageway through the cell membrane made up of proteins. -Transport proteins (carrier proteins) = proteins in the cell membrane that pick up and carry molecules through the cell membrane -different types move different types of particles 17

18. Other Active Transport Endocytosis =define -may also be called engulfing Exocytosis: define These are opposite processes http://www.maxanim.com/physiology/Endocytos is%20and%20Exocytosis/ee4.swf http://www.maxanim.com/physiology/Endocytos is%20and%20Exocytosis/ee4.swf http://academic.brooklyn.cuny.edu/biology/bio4f v/page/endocyta.htm http://academic.brooklyn.cuny.edu/biology/bio4f v/page/endocyta.htm 18

19. http://www.estrellamountain.edu/faculty/farabee/biobk/endocytosis.gif New Vesicle will fuse with a lysosome 19

20. bp1.blogger.com/.../s400/exocytosis5.jpg 20

21. http://homepage.psy.utexas.edu/homepage/Cl ass/Psy308/Salinas/Neurotransmission/release.gif 21

22. Movement of Molecules Process Requires Energy?Movement Passive Transport Active Transport NoHigh to low concentration YesLow to high concentration 22