PG. 21
Types of Cellular Transport:
Passive Transport
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1
Keywords/ Essential Questions
1. Semipermeable membrane
2.Passive transport
a) Diffusion
b) Osmosis
c) Solute concentrations
d) Facilitated Diffusion
Semipermeable Membrane
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-Only small and
uncharged
molecules can
freely pass
through
membrane.
-Bigger, charged
(+/-) molecules
cannot freely
pass.
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Three Forms of Transport Across the Membrane
Passive
transporttransport that
does NOT
require energy
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Passive Transport
Simple Diffusion
❖ Doesn’t require energy
❖ Molecules moves from high to low
concentration, down the concentration
gradient
❖ Example: Oxygen or water diffusing into
a cell and carbon dioxide diffusing out.
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Diffusion through a
Membrane
Cell membrane
Solute moves DOWN concentration gradient (HIGH to LOW)
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Osmosis
Diffusion across a membrane
• Diffusion of water across
a membrane
• Moves from HIGH water
potential (low solute) to
LOW water potential
(high solute)
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Semipermeable
membrane
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Example of Osmosis: Aquaporins
• Water Channels
• Protein pores used during
OSMOSIS
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WATER
MOLECULES
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VOCAB
_____________
SOLUTE
= substance that is
dissolved in a solvent to make a solution
SOLVENT = substance in which a
_____________
solute is dissolved
http://www.makash.ac.il/h_school/hst/hstsb/chem/luach/dissolve.jpg
Use new vocab to make Koolaid
Koolaid powder
sugar
Solutes = ______________&
__________
Water
Solvent = ____________
solution
Koolaid drink = ______________
http://www.makash.ac.il/h_school/hst/hstsb/chem/luach/dissolve.jpg
Solute Concentrations
Water
moves
INTO
the cell
Less solute
(more water) on
the outside of
cell than the
inside
HYPOTONIC
Water
moves
IN and
OUT of
the cell
equally
Water
moves
OUT of
the cell
Equal solutes
(equal water)
on both sides
of cells
More solutes (less
water) on the
outside of the cell
than the inside
ISOTONIC
HYPERTONIC
http://www.stchs.org/science/courses/sbioa/metenergy/bloodcells.gif
Animal cells
Isotonic
Hypotonic
= CYTOLYSIS
Hypertonic
Plant cells
http://www.stchs.org/science/courses/sbioa/metenergy/aplantturgor.gif
Isotonic
Hypotonic
_____
keeps
plant cells from bursting
Hypertonic
___________
= PLASMOLYSIS
VACUOLES store WATER
http://www.biology4kids.com/files/cell_vacuole.html
OSMOTIC PRESSURE
_____________________________
=
Pressure exerted by the movement of water
during osmosis
Passive Transport
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.
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Facilitated Diffusion
Molecules will randomly move through the
pores in Channel Proteins.
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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.
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17
Cell in Isotonic Solution
10% NaCL
90% H2O
ENVIRONMENT
CELL
10% NaCL
90% H2O
NO NET
MOVEMENT
HINT: Ask yourself where is
there more water?
- There is equal amounts of
water on the inside and
outside of the cell, 90%
H20.
Water will always want to
move from HIGH
concentration to LOW!
- Since concentrations are
equal water will move in
BOTH directions .
What is the direction of water movement?
equilibrium
The cell is at _______________.
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Cell in Hypotonic Solution
10% NaCL
90% H2O
CELL
20% NaCL
80% H2O
HINT: Ask yourself where
is there more water?
- There is more water
outside of the cell, 90%
H20
Water will always want to
move from HIGH
concentration to LOW!
- Water will move into the
cell where there is less
water.
What is the direction of water movement?
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Cell in Hypertonic Solution
15% NaCL
85% H2O
ENVIRONMENT
CELL
5% NaCL
95% H2O
HINT: Ask yourself where
is there more water?
- There is more water
inside of the cell, 95%
H20
Water will always want to
move from HIGH
concentration to LOW!
- Water will move out of
the cell into the
environment where
there is less water.
What is the direction of water movement?
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