Cell Transport
The cell membrane lets thing in and out of the cell
Carbohydrates
Cholesterol
Protein Channel
Cytoskeleton
Phospholipids
The cell membrane is selectively
permeable
• This means:
it selects what can come
into the cell
• “Semipermeable”
outside cell
H 2O
NH3
inside cell
sugar
lipid
aa
salt
Remember...
• Phosphate group head
–hydrophilic (likes water)
• Fatty acid tails
–hydrophobic (hates water)
• Arranged as a bilayer (bi = 2)
 Cell membrane is the boundary between inside &
outside…
 separates cell from its environment
Can it be an impenetrable boundary?
IN
OUT
food
carbohydrates
sugars, proteins
amino acids
lipids
salts, O2, H2O
•
OUT
waste
ammonia
salts
CO2
H2O
products
IN
cell needs materials in & products or
waste out
How do things get through the cell
membrane?
• Passive Transport
• Diffusion
• Osmosis
• Facilitated Diffusion
• Active Transport
Diffusion
• Movement of solutes from high to low
concentration
• No energy is needed
SOLUTE
MEMBRANE
WATCH
• The ink will diffuse in the water
Facilitated Diffusion
• Facilitated Diffusion:
Molecules need a
protein channel to pass through the cell
membrane, no ATP needed
Protein Channel
Facilitated Diffusion
facilitated = with help
•
•
•
Protein channel allows
specific molecules to
pass
Like the bouncer of a
club!
No energy is needed
high
low
“The Bouncer”
Osmosis
• Osmosis: the diffusion of water through
a cell membrane
Concentration of water
 Direction of osmosis is determined by
comparing total solute concentrations
Hypertonic - more solute, less water

Hypotonic - less solute, more water

Isotonic - equal solute, equal water

 Cell survival depends on balancing water
uptake & loss
Active Transport
•
•
•
Active Transport:
Molecules need a
protein pump to get
into cell
Uses Energy =
low
ATP
ATP
Goes from low to
high= UP the
concentration gradient
high
“The Doorman”
Endocytosis
phagocytosis
•
•
Endocytosis: taking
things into the cell in
vesicles
Examples:
Phagocytosis and
Pinocytosis
pinocytosis
How do larger molecules get in and
out of the cell?
endocytosis
 phagocytosis =
“cellular eating”
 pinocytosis =
“cellular drinking”
 exocytosis

Exocytosis
•
Exocytosis: molecules
exit the cell in vesicles
Watch & Try
• http://www.classzone.com/cz/books/bio
_07/get_chapter_group.htm?cin=2&rg=
animated_biology&at=animated_biolog
y&var=animated_biology
Review
Work on cell transport worksheet