Transcript Types of Transport Across Cell Membranes

Types of Transport
Across Cell
Membranes
Simple Diffusion
• Requires NO energy, passive movement
• Molecules move from area of HIGH to LOW
concentration
• Random movement
of particles
Brownian Movement
Diffusion of Liquids
Diffusion through a Membrane
Cell membrane
Solute moves DOWN concentration gradient
(HIGH to LOW)
Osmosis
• Diffusion of WATER across a membrane
• Moves from HIGH water concentration to LOW
water concentration
Diffusion across a membrane
Semipermeable
membrane
Three types of conditions
• Isotonic solutions
– When the amount of solutes is equal inside and
outside of cell (cell will stay the same)
• Hypotonic solution
– When solutes outside are lower than inside cell
(cell will swell) * more water outside
• Hypertonic solution
– When solutes outside are higher than inside cell
(cell will shrink) * more water inside cell
Cell in Isotonic Solution
10% NaCL
90% H2O
ENVIRONMENT
CELL
10% NaCL
90% H2O
NO NET
MOVEMENT
What is the direction of water movement?
equilibrium
The cell is at _______________.
Cell in Hypotonic Solution
10% NaCL
90% H2O
CELL
20% NaCL
80% H2O
H2O
What is the direction of water movement?
Cell in Hypertonic Solution
15% NaCL
85% H2O
ENVIRONMENT
CELL
5% NaCL
95% H2O
H2O
What is the direction of water movement?
Cells in Solutions
Isotonic Solution
NO NET
MOVEMENT OF
H2O (equal amounts
entering & leaving)
Hypotonic
Solution
CYTOLYSIS
Hypertonic
Solution
PLASMOLYSIS
Osmosis in Red Blood Cells
Isotonic
Hypotonic
Hypertonic
Hypotonic
Hypertonic
Hypertonic
Isotonic
Isotonic
Hypotonic
Moving Things in and out of Cells
Cellular Transport
A.Passive Transport
(2 types)
1.Simple Diffusion
 Doesn’t require energy
 Moves high to low
concentration (Down)
 Example: Oxygen or
water diffusing into a
cell and carbon dioxide
diffusing out.
2. Facilitated diffusion
Doesn’t require energy
Uses transport
proteins to move high to
low concentration
Examples: Glucose or
amino acids moving from
blood into a cell.
2.Facilitated Diffusion
Molecules will randomly move through
the pores in Channel Proteins.
2.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.
B.Active Transport
Requires energy or
ATP
Moves materials from
LOW to HIGH
concentration
AGAINST (up)
concentration gradient
Sodium-Potassium Pump
3 Na+ pumped in for every 2 K+ pumped
out; creates a membrane potential
1. Endocytosis Moving the “Big Stuff”
Large molecules move materials into the cell by.
Endocytosis
• Cell forms an
invagination
• Materials dissolve
in water to be
brought into cell
• Called “Cell
Drinking”
2.Exocytosis
The opposite of endocytosis is exocytosis. Large
molecules that are manufactured in the cell are
released out of the cell through the cell
membrane.
Inside Cell
Cell environment
Exocytosis