Anatomy and Physiology
Cell Transport
Types of Transport
Diffusion
• Characteristics
– Particles move from
an area of high
concentration to an area
of low concentration.
– Moves “down” or “with”
the concentration
gradient. (difference in
concentration)
– Does not require energy.
Types of Transport
• Factors effecting the rate of
diffusion
– Temperature - as temperature
increase, rate of diffusion increases.
– Pressure - as pressure increases, rate
of diffusion increases.
– Steepness of the concentration
gradient - the steeper the gradient,
the faster the rate of diffusion.
Types of Transport
• Diffusion will continue until dynamic
equilibrium is reached.
• Dynamic equilibrium - continuous
movement of particles, but no overall
concentration change. (Everything is
equally distributed).
Type of Transport
Osmosis
• Characteristics
– Movement of
water across a cell
membrane.
– Cell has no control
over movement of
water. It continues
to move until
[inside] =
[outside].
[ ] =concentration
Osmosis
DILUTE SOLUTION
CONCENTRATED SOLUTION
Cell membrane
partially
permeable.
Sugar molecule
VERY Low
concentrationof
water molecules.
Inside cell
Outside cell
VERY High concentration
of water molecules.
AS Biology, Cell
membranes and Transport
6
Osmosis
Cell membrane
partially
permeable.
Low conc. of
water molecules.
OSMOSIS
High conc. of
water molecules.
Inside cell
Outside cell
AS Biology, Cell
membranes and Transport
7
Osmosis
Cell membrane
partially
permeable.
OSMOSIS
Inside cell
Outside cell
EQUILIBRIUM. Equal water concentration on each side.
Equal water potential has been reached. There is no net
movement of water
– waterCell
moves in and out of8 cell at the
AS Biology,
same rate.
membranes and Transport
What is a
solution?
2 Parts:
•Solvent – Usually a liquid like water
•Solute – Usually a solid such as sugar,
salt
Isotonic Solution
•
Osmosis
Animations for
isotonic, hypertonic,
and hypotonic
solutions
Isotonic: The concentration of solutes in the solution
is equal to the concentration of solutes inside the cell.
ISO = THE SAME
Result: Water moves equally in both directions and
the cell remains same size! (Dynamic Equilibrium)
Osmosis - Types of Solutions
Isotonic
• [water inside] =
[water outside]
• Dynamic
equilibrium
reached
immediately.
Normal Red blood cells
Hypotonic Solution
•
Osmosis
Animations for
isotonic, hypertonic,
and hypotonic
solutions
Hypotonic: The solution has a lower concentration
of solutes and a higher concentration of water than
inside the cell. (Low solute (HYPO); High water)
Result: Water moves from the solution to inside the
cell): Cell Swells and bursts open (cytolysis)!
Osmosis - Types of Solutions
Hypotonic
• [water inside] <
[water outside]
• Solutes are higher
inside the cell.
• Water flows in, cell
swells.
• Cell could burst if
water flow
continues.
Swollen red blood cells
Hypertonic Solution
•
Osmosis
Animations for
isotonic, hypertonic,
and hypotonic
solutions
Hypertonic: The solution has a higher
concentration of solutes and a lower concentration
of water than inside the cell. (High solute (HYPER);
Low water)
shrinks
Result: Water moves from inside the cell into the
solution: Cell shrinks (Plasmolysis)!
Osmosis - Types of Solutions
Hypertonic
• [water inside] >
[water outside].
• Solutes are higher
outside the cell.
• Water leaves the
cell, cell shrinks.
Dehydrated red blood
cells
Types of transport
Passive vs. Active Transport
• Passive - no energy required
• Active - energy required
Types of Cellular
Transport
•
Weeee!!
!
Passive Transport
cell doesn’t use energy
1. Diffusion
2. Facilitated Diffusion
3. Osmosis
•
•Animations of Active
Transport & Passive
Transport
high
low
Active Transport
cell does use energy
1. Protein Pumps
2. Endocytosis
3. Exocytosis
This is
gonna
be hard
work!!
high
low
Types of Transport
• Passive Transport
– Movement across
a membrane by
diffusion.
– Facilitated diffusion
- moves down the
concentration
gradient with the aid
of a protein molecule.
• Most glucose
moves this way
Passive Transport:
2. Facilitated Diffusion A
2. Facilitated diffusion:
diffusion of specific
particles through
transport/carrier
proteins found in the
membrane
a.Transport Proteins are
specific – they “select”
only certain molecules
to cross the membrane
b.Transports larger or
charged molecules
•
Facilitated
diffusion
(Channel
Protein)
http://bio.winona.edu/berg/Free.htm
Carrier Protein
B
Diffusion
(Lipid
Bilayer)
Types of Transport
• Active Transport
– moves from an area
of low concentration
to an area of high
concentration.
– Moves up or against
the concentration
gradient.
– Glucose moving from
blood stream into
liver for storage.
Types of Transport
• Bulk Transport
– Moving large particles across the cell
membrane.
– Endocytosis - movement
– into the cell
– Exocytosis - movement out of the cell
• Cell changes shape –
requires energy
• EX: Hormones or
wastes released from
cell
Paramecium
Contractile vacuole full
Contractile vacuole empty
Bulk Transport
• Endocytosis - 2 types
– Pinocytosis- bulk
transport of liquids
into the cell.
– Phagocytosis- “cell
eating”- bulk transport
of solids into the cell.
•
•
•
•
Cell membrane in-folds around food particle
“cell eating”
forms food vacuole & digests food
This is how white blood cells eat bacteria!