chapter 5 membrane composition and fluidity.. you must know why membranes are selectively permeable....
TRANSCRIPT
Chapter 5Membrane composition and fluidity.
You Must Know
• Why membranes are selectively permeable.
• The structure and function of membrane proteins.
Figure 5.4-1
Mouse cellHuman cell
Membrane proteins
The Fluidity of Membranes
Membranes must be fluid to work properly; they are usually about as fluid as salad oil.
Amphipathic molecules
Fluid Mosaic Model
Figure 5.2
Glyco-protein Glycolipid
Fibers of extra-cellular matrix (ECM)
Carbohydrate
Cholesterol
Microfilamentsof cytoskeleton
Peripheralproteins
EXTRACELLULARSIDE OF
MEMBRANE
CYTOPLASMIC SIDE OF MEMBRANE
Integralprotein
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Which of the amino acids below would you be more likely to find in section “A” of the protein?
Integralprotein
A
Which of the amino acids below would you be more likely to find in section “B” of the protein?
Integralprotein
B
Figure 5.5
Fluid
Unsaturated tails preventpacking.
Viscous
Saturated tails packtogether.
Cholesterol reducesmembrane fluidity atmoderate temperatures,but at low temperatureshinders solidification.
© 2014 Pearson Education, Inc.
Cholesterol
Evolution of Differences in Membrane Lipid Composition
Would bacteria adapted to living in very hot conditions have more saturated or unsaturated fatty acids in their membranes?
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Unsaturated tails Saturated tails
Evolution of Differences in Membrane Lipid Composition
• Would bacteria adapted to living in very cold conditions have more saturated or unsaturated fatty acids in their membranes?
© 2014 Pearson Education, Inc.
Unsaturated tails Saturated tails
Evolution of Differences in Membrane Lipid Composition
The ability to change the lipid compositions in response to temperature changes has evolved in organisms that live where temperatures vary.
© 2014 Pearson Education, Inc.