1. Cell Membrane: Transport
Diffusion SC.912.L.14.2 Relate structure to function for the components of plant and animal cells. Explain the role of cell membranes as a highly selective barrier (passive and active transport)

2. Cell Membrane
Objective: explain how materials pass through a semipermeable membrane
EQ: How do materials
pass through the cell
membrane?

3. Cell Membrane
Structure:
Function:
Phospholipid bilayer that contains channel protein, cholesterol, and carbohydrate chains
Provide a protective barrier around the cell
Control what enters and exits the cell; semi-permeable
like security

4. Suggestions? What did they use for: Phospholipid? Cholesterol?
Protein Channel?

5. Suggestions? What did they use for? Phospholipids? Cholesterol?
Protein Channel?

6. Suggestions? What did they use for: Phospholipid? Cholesterol?
Channel Protein?

8. Making Observations
On the LEFT side of your notebook, make some observations about the beaker of Iodine and starch filled “cell”
When Iodine and starch mix, the solution will turn purple.
Predict: what do you think will happen when we place the “cell” into the beaker of Iodine?

9. Review: the Membrane
What molecules are able to easily pass from one side of the membrane to the other? Why?
Some materials (small, nonpolar) can move across the membrane without help; some (usually larger, polar molecules) use the channels made by proteins to move across the membrane

10. Active Transport
drives molecules against the concentration gradient from areas of low concentration to regions of HIGH concentration
Transport proteins in the membrane use chemical energy (ATP) to move molecules across the membrane

11. Types of Active Transport:
Protein pumps: Smaller molecules go through protein channels and require ATP
vesicles transport = larger materials move across the cell membrane through vesicles
This requires an input of energy

12. Recall:
When we discussed energy in reactions, we used the terms “endothermic” and “exothermic” – what did the prefixes “endo” and “exo” mean?
Endo = into; coming in; absorbed
Exo = out of; released; leaving (exiting)

13. Active Transport via Vesicles
Endocytosis:
Exocytosis:
the RELEASE of substances OUT of a cell using energy
A vesicle forms around materials inside the cell
The vesicle fuses to the cell membrane
The contents of the vesicle are released out of the cell
process of taking large molecules or liquids INTO a cell using energy
The cell membrane pinches in, making a pocket/vesicle for the substance
The pocket pinches off inside the cell
The membrane of the vesicle is broken down by enzymes (ex. from lysosomes) inside the cell to release the materials

14. Active= ATP (energy) Endoccytosis Vesicle transport Active Exocytosis
(low to high)
Vesicle transport
Endoccytosis
Exocytosis
Protein Pump

15. Passive Transport
molecules can move across the cell membrane from HIGH concentration to low concentration
No energy is required

16. Passive Transport: Diffusion
molecules move from a region of high concentration to a region of low concentration
Movement is DOWN a Concentration Gradient
Does not require energy because it is passive transport
Molecules move through phospholipid bilayer

17. Passive Transport: Diffusion
Osmosis
Facilitated Diffusion
still requires NO energy
moves high to low but
through protein channels
Movement of water across the membrane from high to low concentration
No energy required

18. Check for Understanding
Based on what we’ve learned about diffusion, predict the direction that the molecules will move:
Outside
Inside

19. Check for Understanding
Based on what we’ve learned about diffusion, predict the direction that the molecules will move:
Outside
Inside

20. Check for Understanding
Based on what we’ve learned about diffusion, predict the direction that the molecules will move:
Outside
Inside

21. Check for Understanding
Based on what we’ve learned about diffusion, predict the direction that the molecules will move:
Outside
Inside

22. Check for Understanding
Based on what we’ve learned about diffusion, predict the direction that the molecules will move:
Outside
Inside

23. Check for Understanding
Based on what we’ve learned about diffusion, predict the direction that the molecules will move:
Outside
Inside
NO NET MOVEMENT: the molecules go in both directions

24. Diffusion
Our “cell” (ziplock with starch solution) will be placed in the iodine solution and allowed to sit.
When iodine and starch mix, the solution turns purple.
PREDICT: what do you expect will happen?

25. Diffusion lab
After being allowed to sit, the “cell” is removed from the solution and …..
The starch solution has turned purple.
The iodine solution appears unchanged (notice that there is no cloudiness to the solution)

26. Diffusion Questions – left side
Based on your results, which do you think is smaller: iodine molecules or starch molecules? How do you know?
Based on the results of this investigation, rank the following by their relative size, from smallest to largest: water molecules, starch molecules, dialysis tubing pores, and iodine molecules
What is the difference between diffusion (a type of passive transport) and active transport? Which is this experiment?

27. Active vs Passive Transport
Using the grid, test which if the materials fits through on its own and which materials need an extra “push”. Record your findings in your activity sheet. Paste to page ***
C- level 2
H- follow the activity instructions
A- model active and passive transport
M- remain seated at your pod
P- collect data on student sheet and answer questions
Success
Ping pong ball
Beans
Rice
Marble
dice

28. Exit ticket
Clear your desk!