Download Diffusion and Osmosis

Cellular Transport
Section 7.3
How cells move or transport the
stuff they want into the cell & get
the stuff they don’t want out!
Page 208 – “Think About It”
2 Types of Transport
• Passive Transport
– We will talk about this type of transport first!
– Requires no energy.
– 3 Types: diffusion, osmosis, & facilitated diffusion
• Active Transport
– Requires Energy
– 3 Types: Pumps, Endocytosis, Exocytosis
Diffusion
• Definition: movement of molecules from an
area of high concentration to low concentration
• What is concentration?
• Concentration is an amount.
• Example: What does it mean if a pool has a
high concentration of chlorine?
• Why?
– molecules in constant motion, collide, &
spread
– More molecules, higher probability to collide
• When all molecules are equally spread apart this
is called Equilibrium
Membrane Function
The Cell Membrane regulates what enters & exits the
cell!
Maintains Homeostasis!
Serves as a selective barrier meaning the
membrane “selects” what it will allow to
enter or exit the cell
 semi-permeable membrane!
How would the glucose move?
1M
glucose
0.1M
glucose
0.55M
glucose
0.55M
glucose
Types of Diffusion
• Special Case  Osmosis
• Definition = diffusion of water
Concentration Gradient
• Definition = a difference in concentration
across an area
• High  Low =
– down the gradient
• Low  High =
– up the gradient
How does osmosis apply to cells?
• Q: What would happen if we put a cell in pure
water?
What would happen if we put a cell in
salt water?
Shrink
Osmosis in Living Cells
Cellulose in
cell wall
Label the solutions below.