2. CELL TRANSPORT

3. Tomato plant must take in nutrients from the soil. Potassium Nitrogen Phosphorus Every living cell exists in a liquid environment. One of the most important functions of the cell membrane is to keep the cell’s internal conditions relatively constant.

5. IN Food Glucose O2 H2O OUT Waste Hormone CO2 H2O What structure in the cell regulates what substances enter the cell? The cell membrane regulates and controls which substances enter and leave the cell.

6. There are two basic methods by which substances enter/exit the cell: (1) Passive transport --- no energy needed (2) Active transport --- requires energy

7. Passive transport is the movement of substances across a cell membrane from an area of higher concentration to an area of lower concentration. ( requires no energy ) aa sugarsaltO2O2 Higher Concentration Lower Concentration

8. InsideCell What are some characteristics of the cell membrane? Outside Cell Nonpolar---oily

9. InsideCell Small nonpolar substances such as CO 2, O 2, and small lipids can pass through the cell membrane by diffusion. lipids CO 2 O2O2 Outside Cell

10. Diffusion is the movement of substances from a region of higher concentration to a region of lower concentration. High Conc Low Conc Low Conc Low Conc higher conclower conc

11. Equilibrium is the condition in which the concentration of a substance is equal throughout a region. Even at equilibrium, molecules continue to move randomly.

12. Which way will fat move? inside cell outside cell fat LOW HIGH fat That’s diffusion!

13. InsideCell How do polar molecules like glucose get across the nonpolar membrane? Outside Cell Nonpolar--oily glucose By Facilitated Diffusion

14. Channel Proteins Facilitated Diffusion: The diffusion of substances across the cell membrane through channel proteins. passive transport No energy input substance higher conc lower conc

15. InsideCell Proteins in the cell membrane create channels making it easy for certain molecules to pass. Channel Proteins glucose

16. InsideCell Outside Cell Polar molecules like glucose diffuse across the membrane by moving through pores formed by channel proteins. Channel Proteins glucose

17. Osmosis Water is very important, so we talk about water separately. Cell survival depends on balancing water uptake & loss. freshwater balancedsaltwater Normal plant cell ******

18. Osmosis is the movement of water across a cell membrane from a region of higher conc to a region of lower conc. Osmosis is the diffusion of water across a cell membrane. high conc H 2 O low conc H 2 O Cellmembrane

19. high conc H 2 O low conc H 2 O Cellmembrane How does water move? Always from an area of higher concentration to an area of lower concentration.

20. The direction of osmosis depends on the relative concentration of solutes on the two sides of the membrane. low conc solutehigh conc solute Less water more water solute

21. How does water move? low conc solutehigh conc solute Less water more water solute more water less water

22. Cells are always surrounded by some kind of solution. The solution surrounding cells may be: (1) isotonic (2) hypotonic (3) hypertonic

23. An isotonic solution has the same concentration of solute molecules as the cell. iso = same 10 % solute 10 % solute Water moves in and out at the same rate

24. iso = same 2 % salt 2 % salt isotonic solution

25. iso = same 5 % glucose 5 % glucose isotonic solution

26. A hypotonic solution has a lower concentration of solutes than a cell. This means the concentration of water is greater outside the cell than inside. Water will move into the cell Hypo = more water 10 % solute 25 % solute The cell will swell. Less solute

27. 1 % salt 5 % salt hypotonic solution

28. 1 % glucose 2 % glucose hypotonic solution

29. A hypertonic solution has a higher conc of solutes than a cell. The water conc is lower outside the cell than inside. Water will move out of the cell The cell will shrivel. 25 % solute 5 % solute Hyper = less watermore solute

30. 5 % salt 2 % salt hypertonic solution

31. 3 % glucose 1 % glucose hypertonic solution

32. Summing Up! Passive Transport: Movement from high to low No energy Examples: diffusion facilitated diffusion osmosis

33. Contractile vacuole in Paramecium