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Membrane Fluidity : Its contribution to the Dynamic Nature of the Membrane
TeamMawadda Al-Naeeli
Pat Cipriano, Kim Conner, Lopa Das,Thea Edwards, Tara Luke
Facilitators: Michelle Withers & Karen York
Goal
• Understand how the chemical structure of cell membranes underlie their function and adaptability.
• u
OutcomesUpon completion of this teachable unit the student will:
• Explain how fluidity is changed by changes in the components of the membrane.
• Predict how the lipid composition changes to maintain fluidity in extreme environments.
• Practice drawing, reading and interpreting graphs.
Context
Introductory Biology
Omega 3 Fatty Acids
Have you ever heard of Omega 3 fatty acids?
What are they?
What are some good sources of Omega 3 fatty acids?
C-CC-H
Membrane proteins
Mouse cellHuman cell
http://www.youtube.com/watch?v=LicQb_SnCSI
Mixed proteinsafter 1 hour
Hybrid cell
Fluid nature of lipid bilayer of cell membrane
Fluid
Unsaturated hydrocarbontails
Viscous
Saturated hydrocarbon tails
A B
Decrease in fluidity with increase in cholesterol content
Clicker Question
How does an increase in temperature affect membrane fluidity?
A. Increases fluidityB. Decreases fluidityC. No change
Clicker Question
How does an increase in temperature affect membrane fluidity?
A. Increases fluidityB. Decreases fluidityC. No change
Cholesterol Unsaturated Fatty Acids
Saturated Fatty Acids
Cold Water Fishes
Warm Water Fishes
Consider cold water and warm water fishes.
How would membrane composition differ to maintain similar fluidity?
↑ ↓ --
Cholesterol Unsaturated Fatty Acids
Saturated Fatty Acids
Cold Water Fishes
↓ ↑ ↓
Warm Water Fishes
↑ ↓ ↑
Consider cold water and warm water fishes.
How would membrane composition differ to maintain similar fluidity?
↑ ↓ --
Cholesterol Unsaturated Fatty Acids
Saturated Fatty Acids
Cold Water Fishes
↓ ↓
Warm Water Fishes
↑ ↑
Consider cold water and warm water fishes.
How would membrane composition differ to maintain similar fluidity?
↑ ↓ --
Cholesterol Unsaturated Fatty Acids
Saturated Fatty Acids
Cold Water Fishes
↓ ↑ ↓
Warm Water Fishes
↑ ↓ ↑
Consider cold water and warm water fishes.
How would membrane composition differ to maintain similar fluidity?
↑ ↓ --
Cholesterol Unsaturated Fatty Acids
Saturated Fatty Acids
Cold Water Fishes
↓ ↑
Warm Water Fishes
↑ ↓
Consider cold water and warm water fishes.
How would membrane composition differ to maintain similar fluidity?
↑ ↓ --
Cholesterol Unsaturated Fatty Acids
Saturated Fatty Acids
Cold Water Fishes
↓ ↑ ↓
Warm Water Fishes
↑ ↓ ↑
Consider cold water and warm water fishes.
How would membrane composition differ to maintain similar fluidity?
↑ ↓ --
• Using your dataset, draw a graph that would show the effects of changing temperature on membrane cholesterol and omega-3 fatty acid (unsaturated) content.
Hassett R P , and Crockett E L J Exp Biol 2009;212:71-77
Relationship between cholesterol content and habitat temperature in copepods.
Which of the following would occur when a tropical fish suddenly finds itself in the Arctic?
1. Membranes are more rigid2. Membranes are more fluid3. Membranes maintain the same fluidity
Which of the following would occur when a tropical fish suddenly finds itself in the Arctic?
1. Membranes are more rigid2. Membranes are more fluid3. Membranes maintain the same fluidity4. The organism dies5. The organism survives6. Membrane maintains function7. Membrane loses function8. Lipid composition changes9. Lipid composition stays the same
Which of the following would occur when considering the membrane of an organism that…
(is exposed to colder temperatures than it normally experiences?)(is exposed to warmer temperatures than it normally experiences?)(is a psychrophile?)(is a thermophile?)(has a high level of cholesterol in its membrane?)(has a low level of cholesterol in its membrane?)(contains mostly saturated fats?)(contains mostly unsaturated fats?)
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