Team “Insane in the Membrane”
Team members: Heather Addy, Anna Davis, Cindy
Graham, Joan Marshall, Vesal Mahanian
Membrane Structure
and Function
26 July 2012
Learning Goals




Understand why phospholipids
spontaneously arrange into micelles and
vesicles when mixed in water
Identify the properties/structure of
phospholipid bilayers make them selectively
permeable.
Collaborate with others to solve a problem
Learn to communicate and defend a
scientific argument based on experimental
evidence
After this session you will be able
to…
(1)
(2)
(3)
Predict (and draw) the arrangements of
phospholipids in an aqueous solution,
based on their chemical properties
Deduce the properties that govern
membrane permeability of molecules from
experimental data
Evaluate whether different compounds
can diffuse across a simple lipid bilayer
based on polarity, size and charge.
Foundations
 Previously
we learned about the…
Importance of intermolecular forces
 Relationship between polarity and
hydrophobicity
 How functional groups influence the
chemical properties of molecules
 Properties of water

Oil and water don’t mix
Oleic Acid (Lipid)
Water
Phospholipids are amphipathic
Properties of Phospholipids
If we mix phospholipids
in water, how will they
organize?
In a group of 3, draw at
least 2 arrangements of
phospholipid molecules
in water...
2 minutes
Phospholipids spontaneously form
micelles and bilayers in water

Fatty acid chains
aggregate together

Phosphate-containing
head groups
associate with water
Is this arrangement possible?
What properties determine whether a
molecule crosses a phospholipid
bilayer?
Small Group Activity

In a recent experiment, the
permeability coefficient of
various molecules was
determined

Organize the molecules in order
of permeability and consider
what structural/chemical
features contribute to their
permeability
5 minutes
Summative Assessment:
#1
Which can pass
through a membrane
more readily?
Why?
#2
Summative Assessment: Answer
#1 Vitamin B2: Water soluble, cannot pass
through a phospholipid bilayer because it’s
large and polar
Which can pass
through a membrane
more readily?
Why?
#2
#2 Vitamin E: Fat soluble, is
able to pass through the
phospholipid bilayer because
it’s non-polar (looks like a fat)
#1
Thank you!
Supplemental Material
Progesterone
P=3.5x10E-4
cm/s
O=O
Oxygen
P=42
cm/s
Small
Group
Activity
Cards
Acetate
P=1x10E-12
cm/s
Acetic acid
P=2x10E-2 cm/s
Glycerol
P=5x10E-5 cm/s
Na
+
Glucose
P=2x10E-7 cm/s
Sodium ion
P=1x10E-12 cm/s
Water
P=5x10E-2 cm/s