1. Chapter 7.3 Cell Transport

2. Concentration Gradient
Concentration – the amount of solute compared to water in the solution
High Concentration = large amount of solute in the solution
Low Concentration = small amount of water in the solution
Concentration Gradient– the difference in the amount of solute between different parts of the solution (sometimes across two sides of a membrane).

3. Cell membrane transport
There are 2 types of cell membrane transport:
Passive Transport
Things flow from
High to low concentration
DOES NOT USE ATP (energy)
Active Transport
Low to high concentration
USE ATP (energy)

4. Another perspective on passive and active transport

5. THE GOAL IS…..Equilibrium!!!
When is equilibrium reached when discussing cell membrane transport?
When the concentrations of particles are the same on both sides

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

7. 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.

8. Facilitated diffusion

9. Passive transport Osmosis
The facilitated diffusion of water across a selectively permeable membrane
Important in maintaining cell homeostasis
Water moves from high concentration to low concentration

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

11. Review of Solution Terms
Solution = Saltwater Solvent = Water Solute = Salt

12. Osmosis – Types of Solutions
When dealing with osmosis, water can either move into the cell or out of it.
The solute cannot 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 %
solute
What are the concentrations?
40% solute

13. 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

14. Isotonic solution

15. 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

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

17. Plant and animals cells in a Hypertonic Solution

18. 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

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

20. Plant and animal cells in a hypotonic solution

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

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

23. Active Transport Molecular Transport – moves small molecules
Protein Pumps
Bulk Transport- moves larger molecules
Endocytosis
Exocytosis

24. Protein Pumps
Small molecules and ions carried across the cell membrane by proteins in the membrane that act like pumps

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

26. 2 types of Endocytosis Phagocytosis Pinocytosis
Engulfing of large particles
from outside the cell
Pinocytosis
Engulfing of
liquids from
outside the cell

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