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Passive
Transport
Fluid Mosaic Model
Passive Transport
Does not expend
cellular energy
for the
movement to
take place
Ex-rolling down a
hill
Parts of a Solution
Solute:
what gets dissolved
Solvent:
What does the dissolving, more plentiful that solute
Solution:
the mixture of solutes and solvent
Example: H2O and NaCl
Solute: NaCl
Solvent: H2O
Solution: H2O and NaCl
3 types of Passive
Transport:
1. Diffusion
2. Osmosis
3. Facilitated Diffusion
Diffusion
Passive Transport WITHOUT a
Membrane
I. DIFFUSION:
Definition:
Transport of molecules (of solutes
and solvents)
From an area of higher
concentration to an area of lower
concentration
Until equal distribution of
concentrations reached in all areas
(EQUILIBRIUM)
Due to the random movement of
molecules
Conceptual Diagram:
Review of the Types of
Membranes:
1. Permeable
2. Impermeable
3. Semi-permeable
1.
Permeable
ALL types of molecules can get
through, regardless of size or
charge.
2. Impermeable
(non-permeable)
NO molecules can get through
3.
SEMI-PERMEABLE !!!:
SOME
MOLECULES CAN
GET THROUGH
Very small or
Non-charged
Diffusion: Without a Membrane
Osmosis: With a Membrane
Osmosis and Facilitated
Diffusion
Passive Transport WITH a
Membrane
II.
OSMOSIS:
Definition:
Diffusion through a membrane:
Movement of H2O
from to high to low concentration
THROUGH A MEMBRANE
until equilibrium
II.
OSMOSIS:
II.
OSMOSIS:
U-tube Osmosis
How do you get different
concentrations of water (2
ways)?
1. Change the amount of solute or
solvent.
2. Add a membrane
3 Types of Solutions
(outside of cell):
1. Hypertonic
2. Hypotonic
3. Isotonic
1.Hypertonic:
MORE
More solute, less solvent
(H2O) outside of the cell
90% water
80% water
2. Hypotonic:
LESS
Less solute, more solvent outside of the
cell.
3. Isotonic:
EQUAL
Equal amounts of
solute/solvent
concentrations
on both sides of
membrane
(a)
Isotonic
Water concentration inside the
cells is equal to the water
concentration in the fluid
surrounding the cell. Therefore,
there is no net movement of
water either into or out of the
cell.
(b)
Hypertonic
Water concentration in the
surrounding medium is lower
than it is in the cell. Water
moves out of the cells and the
cells shrivel (crenate).
(c)
Hypotonic
Water concentration outside
the cell is greater than it is
inside the cell. Water moves
into the cell, which swell and
sometimes burst – a process
called lysis.
Consequences:
Hypertonic  Cell Shrinking
In a plant cell: PLASMOLYSIS
In an animal cell: CRENATION (Shriveled)
Examples:
Drinking out of ocean when you are dying of
thirst or
Placing a fresh water fish or plant in salt water…

Plant Wilting sue to lack of water 
Consequences:
(a)
Isotonic
Water concentration inside the
cells is equal to the water
concentration in the fluid
surrounding the cell. Therefore,
there is no net movement of
water either into or out of the
cell.
(b)
Hypertonic
Water concentration in the
surrounding medium is lower
than it is in the cell. Water
moves out of the cells and the
cells shrivel (crenate).
(c)
Hypotonic
Water concentration outside
the cell is greater than it is
inside the cell. Water moves
into the cell, which swell and
sometimes burst – a process
called lysis.
Consequences:
Hypotonic 
In a plant cell: TURGID (Firm)
In an animal cell: CYTOLYSIS (Lysed: Cell
Bursting)
Examples:
Place a salt water fish in fresh water 
Red Blood Cells in pure water
Plants standing tall after
being watered
Osmotic Pressure = Turgor Pressure
As a result of osmosis, extra water
molecules accumulate on one side
of membrane and cause pressure
on the membrane
 “Turgor”
Example:
water
III. FACILITATED DIFFUSION:
Protein Channels in the cell membrane
accept only specific molecules, like a lock
accepts a particular key.
III. FACILITATED DIFFUSION:
III. FACILITATED DIFFUSION:
Many of these protein channels are
“two-way” and are called PORES.
These transport ions or molecules
(solutes) through membranes in
either direction
III. FACILITATED DIFFUSION:
Like an open door allows you to pass into
or out of a room.
Different solute molecules fit different pores
This depends on
Size
Polarity
Shape of molecule
Eg. Glucose
III. FACILITATED DIFFUSION:
When a solute that
is plentiful on one
side of membrane,
they will pass by
diffusion toward
other side with the
lower
concentration.
Until concentration
becomes equal on
both sides
DON’T FORGET,
THESE WERE ALL
PASSIVE TRANSPORT
–SO THE CELL DID NOT NEED
TO EXPEND ANY NRG TO
MAKE IT HAPPEN!!!!!