1. Passive Transport
Unit 2
Cytology

2. Passive Transport
Movement of substances across a membrane without any input of energy
3 Types:
Diffusion
Osmosis
Facilitated diffusion
Move with the concentration gradient

3. Concentration Gradient
Difference in concentration across a space

4. Diffusion Driven by molecules’ kinetic energy (No extra energy needed)
Molecules move from an area of high concentration to an area of low concentration.
Depends on
Molecule concentration
Molecule size
Temperature

6. Facilitated Diffusion
Larger or polar molecules move across membrane with the help of protein channels
Glucose, water, amino acids
No extra energy needed

7. No ATP is involved!!

8. Osmosis A specific type of diffusion
Movement of WATER across semi-permeable membrane.
From high water concentration to low water concentration
Water moves from low
solute to high solute.
Continues to equilibrium
is reached.

9. Effects of Osmosis on Cells
Solution
What it looks like
Animal Cell
Plant Cell
Isotonic:
The concentration of solutes is the same inside and outside of the cell
10% solute
90%water
Hypertonic:
Solution has a higher solute concentration than the cell
20% solute
80%water
Hypotonic:
Solution has a lower solute concentration than the cell
0% solute
100%water
H2O
10% solute
90%water
Plasmolysis: cell membrane peels away from cell wall.
H2O
Crenellation
10% solute
90%water
Turgor Pressure: Won’t burst because of cell wall.
H2O
10% solute
90%water
Lysis