1. Passive Transport
This is going to show how cells transport substances in and out. 1

2. The cell membrane is trying to maintain HOMEOSTASIS
or balance, by moving substances (solutes or solvents) across the membrane to where they are needed.

3. Substances Solute Solvent The substance being dissolved
The substance that does the dissolving
Ex. Sugar dissolving in H2O
What is the solvent?
What is the solute?
Sugar
Water

4. How does a membrane know which direction a substance needs to move?
In most cases the substance tries to reach a state of equilibrium.

5. Equilibrium
A stable or balanced system.

6. Equilibrium
-EQUAL; the same - NOT EQUAL
amount throughout

7. Concentration Gradient Notice how both examples are NOT in Equilibrium
High Difference=
High Concentration Gradient
A concentration gradient represents a change in the concentration of a solute over a distance in a solution
Low Difference =
Low Concentration Gradient

8. Speed of movement based on Concentration Gradient
Low
Gradient
High
Gradient
Small difference = moves slow
Large difference = moves fast

9. Transport 1.) Passive Transport 2.) Active Transport
Materials can move in and out of the cell in two ways:
1.) Passive Transport
(no energy)
2.) Active Transport
(uses energy)

10. Passive Transport Does not use Energy
Goes with the Flow from High to Low (concentration)
Movement DOWN the concentration gradient
Ex: Diffusion
Osmosis

11. Examples of Passive Transport
Diffusion
Movement from High to Low Concentration
Osmosis
Movement of WATER from High to Low Concentration through a membrane

12. Diffusion Does NOT use energy (goes by itself) Goes with the FLOW from
HIGH to LOW

13. Diffusion of Liquids 13 The Plasma Membrane 12/3/2018
G. Podgorski, Biol. 1010 13

14. Proteins used for transport
Remember?
Proteins used for transport
Some proteins act like channels or tunnels where materials can flow through by PASSIVE TRANSPORT
This is called
Facilitated Diffusion

15. Facilitated Diffusion (Diffusion with Help)
Large molecules can diffuse across a membrane with the help of a protein

16. Facilitated Diffusion
The Plasma Membrane
12/3/2018
Facilitated Diffusion
Molecules will randomly move through the pores in Channel Proteins. 16
G. Podgorski, Biol. 1010 16

17. Facilitated Diffusion
The Plasma Membrane
12/3/2018
Facilitated Diffusion
Some Carrier proteins do not extend through the membrane.
They bond and drag molecules through the lipid bilayer and release them on the opposite side. 17
G. Podgorski, Biol. 1010 17

18. The Plasma Membrane
12/3/2018
Carrier Proteins
Other carrier proteins change shape to move materials across the cell membrane 18
G. Podgorski, Biol. 1010 18