diffusion
Selectively Permeable Membrane
to choose
to pass through
thin outer boundary
A?
B?
Gate keeper for friendly folks but not enemies
Selectively Permeable Membrane
Membrane is
permeable to:
Membrane is NOT
permeable to:
H2O
NaCl2
O2
Macromolecules
(potassium,
Calcium, sodium)
CO2
Then how do these important substances move in and out of the cell membrane?
They move in & out of the membrane
by one of these ways:
1-diffusion
passive transport
2- osmosis
3- transport protein
active transport
4- engulfing
What is Diffusion?
 Molecules tend to move from an area of higher concentration
to an area of lower concentration.
Diffusion
How do these paramecium get the oxygen they need to
survive from the water around them?
More oxygen in water than inside their cell so it diffuses
from high to low concentration.
What is OSMOSIS?
-diffusion of water molecules through a
selectively permeable membrane
Osmosis
Diffusion and Osmosis are
considered Passive Transport.
H2O
O2
CO2
Passive Transport-no energy
needed, just equilibrium.
Diffusion & Osmosis
If Passive transport doesn’t use energy then
what about Active transport?
NaCl2
Calcium
Potassium
Sodium
Transport protein
Bigger molecules need energy to get in
What do you think this cool
Active transport is called?
ENGULFING !!!
Match these:
 1. Permeable
 2. Osmosis
 3. Membrane
 4. Diffusion
 5. Active Transport
 6. Selectively
 7. Passive Transport
 8. Transport Protein
 9. Engulfing
A. Thin outer boundary
B. Spreading out of particles
C. To choose
D. Amoeba seeking food
E. No energy needed
F. To pass through
G. Revolving door using
energy
H. Water moving across a
membrane
I. Energy needed to scooter
uphill
Cell Movement and Transport