Osmosis
Learning Objective:
In order to be successful in this lesson you must be able to:
Distinguish between facilitated diffusion and diffusion
Osmosis
define osmosis in
terms of water
potential
explain the effect of
osmosis on plant and
animal cells
Interpret data from
experiments on
osmosis and use it to
find the
concentration of
solutions inside cells
Fluid Mosaic Model
Intrinsic Protein
Carbohydrate
Glycolipid
Glycoprotein
A
C
O2
B
Fatty acids
Phospholipid
F
Bilayer
E
Extrinsic Protein
D
Phosphate
CO2
Free Template from www.brainybetty.com
Cholesterol
3
Which is not a function of cell surface
membranes?
1) Forms a boundary between cell surface and
the environment that can control the
substances that enter and leave the cell
2) Allows different conditions to be established
inside and outside the cell
3) Allows cells to communicate with each other
4) Provides surfaces on which reactions can
occur
Name the formation that is created when
phospholipids are shaken in water.
Which is not a function of the
phospholipid bilayer?
1) Allow lipid soluble substances to enter and
leave the cell
2) Prevent water soluble substances entering
and leaving the cell
3) Make the membrane self flexible and self
sealing
4) Provide structural support
Which is a function of extrinsic
proteins?
1. To form channel proteins to allow water
soluble ions to diffuse across the cell
membrane
2. To form carrier proteins that bind to
molecules like glucose and change shape to
move them across the membrane
3. Provide structural support
4. To prevent leakage of water and dissolved
ions from the cell
Which is not a function of cholesterol?
1) Act as recognition site
2) Reduce lateral movement of other molecules
including phospholipids
3) Make the membrane less fluid at high
temperatures
4) Prevent leakage of water and dissolved ions
from the cell
Is cholesterol more common in plant
or animal cells? Why?
Which does a glycolipid consist of?
Which is not a function of a glycolipid?
1) Act as recognition site
2) Maintain stability of the membrane
3) Help cells attach to one another to form
tissues
4) Act as channels transporting water soluble
substances across the membrane
What does a glycoprotein consist of?
Explain the reasons that the fluid mosaic model of the
cell surface membrane is called the fluid mosaic model
Which is not a function of cell surface
membranes?
1) Forms a boundary between cell surface and
the environment that can control the
substances that enter and leave the cell
2) Allows different conditions to be established
inside and outside the cell
3) Allows cells to communicate with each other
4) Provides surfaces on which reactions can
occur
Name the formation that is created when
phospholipids are shaken in water.
Micelles
Which is not a function of the
phospholipid bilayer?
1) Allow lipid soluble substances to enter and
leave the cell
2) Prevent water soluble substances entering
and leaving the cell
3) Make the membrane self flexible and self
sealing
4) Provide structural support
Which is a function of extrinsic
proteins?
1. To form channel proteins to allow water
soluble ions to diffuse across the cell
membrane
2. To form carrier proteins that bind to
molecules like glucose and change shape to
move them across the membrane
3. Provide structural support
4. To prevent leakage of water and dissolved
ions from the cell
Which is not a function of cholesterol?
1) Act as recognition site
2) Reduce lateral movement of other molecules
including phospholipids
3) Make the membrane less fluid at high
temperatures
4) Prevent leakage of water and dissolved ions
from the cell
Is cholesterol more common in plant
or animal cells? Why?
• Animal cells- no cell wall to provide support
What is your definition of osmosis?
http://highered.mheducation.com/sites/0072495855/student_view0/chapter2/animation__how_osmosis_works.html
OSMOSIS
Movement of water through a
selectively/partially permeable
membrane
from a region of higher water
potential
to a region of lower water potential.
Water potential?
What does that mean?
Lower solute
concentration
Higher water
concentration
Higher water
potential
Higher solute
concentration
Lower water
concentration
Lower water
potential
Cell surface membranes and other
membranes in the cell are partially
permeable.
They are permeable to water molecules
and some other small molecules. They
are not permeable to large molecules
such as protein.
Water potential is given the Greek
letter psi.
Y
Water potential is the pressure exerted
by water molecules in a solution.
Pure water has a water potential of 0.
Therefore all solutions have a water
potential that is less than 0.
That is, the water potential of a
solution is a negative number.
Water will pass by osmosis from
a solution with a less negative
water potential to a solution
with a more negative water
potential, through a partially
permeable membrane.
A
B
Solution A Y = -20kPa
Solution B Y = -30kPa
Solution A has a higher water potential
than solution B.
Water will pass from solution A to solution
B through the partially permeable
membrane.
Partially
permeable
Visking
tubing
Sucrose
solution
Water
The water has a higher Y than the sucrose
solution. Water passes into the Visking
tubing by osmosis. Weigh the Visking tubing
before placing in the water and again after
20 mins. What will happen to the mass?
Potato experiment
• https://www.youtube.com/watch?v=GQAVND
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