Membrane bilayer ICPP Flashcards
What are the components of a lipid bilayer?
40% lipid
60% protein
1-10% carbohydrate
Lipids involved are..
amphipathic phospholipids
What is the only phospholipid not based on glycerol?
sphingomyelin
What is the head group in cerebrosides
a sugar
if the head group is an oligosaccharide is is a..
gangliosides
Describe the structure of cholestrol? How much of the membrane lipid component is it?
polar head group, rigid planar sterol ring structure, non-polar H-C tail
45 %
What are the ways phospholipids can move in a bilayer?
flexion
rotation
flip-flop
lateral diffusion
What happens if cis double bond present in HC chain
kink introduced–> reduced PL packing increasing motion
How does cholestrol contribute to membrane stability?
prevent melting- endothermic phase transition abolished
paradoxical effect
decrease packing to increase motion
decrease lipid chain motion therefore reduce motion
Evidence for membrane proteins?
functional:
ion gradients
facilitated diffusion
specificity of cell responses
biochemical:
membrane fractionation
freeze fracture
How can membrane proteins move?
conformational change
rotational
lateral
flip-flop not thermodynamically possible
How is membrane protein movement restricted?
lipid mediated effects- aggregate in cholestrol rich regions
membrane protein association
association with extra membranous proteins
What is a peripheral protein? How can they be removed?
bound to surface
electrostatic + h bond interactions
removed by changes in pH and ionic strength
What is an integral protein? how can they be removed?
interact with hydrophobic domains of bilayer
removed by detergents and organic solvents that compete or non-polar interactions
What do haemolytic anaemias result from?
problems with RBC cytoskeleton
