1. Chapter 7.3 Cell Transport

2. Warm-Up
What do you know so far about the cell membrane? What do you want to know about the cell membrane?

3. Cell Membrane Structure & Function
Phospholipid Bi-layer (hydrophilic heads, hydrophobic tails)
Fluid-Mosaic Model
Proteins & cholesterol embedded within the phospholipid bi-layer
Selectively Permeable – controls was enters and exits the cell

4. Fluid-Mosaic Model Channel Proteins:
Allow molecules, such as water, to pass through the cell membrane
Recognition/ID Protein:
Has carbohydrate chains attached that are used as ID markers
Allow cells to communicate with eachother and identify foreign invaders (other blood type, virus)

5. Fluid-Mosaic Model Protein Pump: Cholesterol:
Use ATP (energy) to pump substance across the membrane
Cholesterol:
Lipid that controls the fluidity of the cell membrane

6. Cell membrane transport
There are 2 types of cell membrane transport:
Passive Transport
Things flow from
High to low
Active Transport
Low to high

7. Another perspective on passive and active transport

8. Passive Transport Diffusion
The movement of particles from areas of high concentration to low concentration

9. Equilibrium
When is equilibrium reached when discussing cell membrane transport?
When the concentrations of particles are the same on both sides

10. Facilitated Diffusion
Particles flow from high concentration to low concentration but this time they need the help of proteins to get through the cell membrane.

11. Facilitated diffusion

12. Passive transport Osmosis
The diffusion of water across a selectively permeable membrane
Important in maintaining cell homeostasis
Water flows to side of membrane where the water concentration is lower until equilibrium is reached

13. Osmosis
Osmosis is controlled by the amount of solutes on either side of a membrane

14. Osmosis – Types of Solutions
When dealing with osmosis, water can either move into the cell or out of it.
The solute can not move to equal out the solution so the water has to.
We describe the solutions that cells are in as either hypotonic, isotonic, or hypertonic.
90%
What are the concentrations?
40%

15. Isotonic Solution
Isotonic solution – Concentration of solute is the same in the cell and the area around the cell.
Give me an example of an isotonic solution that some of you use everyday

16. Isotonic solution

17. Hypotonic Solution
Hypotonic Solution – Concentration of solute is lower in the solution than in the cell.
Where is water going to move in order to reach equilibrium (Equal concentrations)?
Inside the cell

18. Hypotonic solutions
Since water moves into the cell the cell can explode
So, Hypotonic solution, low concentration of solute, cell can explode

19. Plant and animal cells in a hypotonic solution

20. Hypertonic Solution
Hypertonic solution – concentration of solute is higher in the solution than in the cell.
Where is water going to move in order to reach equilibrium (Equal concentrations)?
Outside the cell

21. Hypertonic solutions
Since water moves out of the cell the cell will shrink
So, Hypertonic solution, high concentration of solute, cell will shrink

22. Plant and animals cells in a Hypertonic Solution

23. Osmosis http://www2.nl.edu/jste/osmosis.htm

24. Active Transport
Molecules move from low concentration to high concentration
Requires energy….why?

25. Active Transport Molecular Transport – Bulk Transport Protein Pumps
Small molecules and ions carried across the cell membrane by proteins in the membrane that act like pumps
Bulk Transport
Endocytosis – in!
Exocytosis – out!

26. Other membrane transport activities that require energy
Endocytosis
Engulfing of large particles or liquids from outside the cell

27. 2 types of Endocytosis Phagocytosis Pinocytosis
Engulfing of large particles
from outside the cell
Pinocytosis
Engulfing of
liquids from
outside the cell

28. Other membrane transport activities that require energy
Exocytosis
Release of large particles or liquids from inside the cell
Outside the cell
Inside the cell