L8. Membrane Flashcards
Give 4 properties of the plasma membrane
Highly selective
Can change shape
Can deform without tearing
Polar
What is the most burdens type of phospholipid
Phosphatidyl choline
What word describes the polarity in the phospholipid bilayer
Amphipathic
Why is it energetically stable to keep the hydrophobic tails on the interior
Because hydrophobic will repel hydrophobic molecules
What is flip flop motion
Where 2 phospholipids either side of the bilayer completely swap sides
What is the function of the phospholipid translocators
Synthesise the membrane
Only made in a monolayer on the cytosolic side so the enzyme flips half the lipids fo form the bilayer
How to close regular packing of tails affect the membrane properties
More viscous
More induced dipoles as closer together
How does low saturation levels affect membrane properties
More double bonds More kinks in the tails Can’t pack as closely together Less induced dipoles More fluid
What is cholesterol
Short rigid molecules that pack in between phospholipids
Cause kinks in unsaturated tails
Less tails
Why are eukaryotic membrane rigid
Have a 1:1 between phospholipids and cholesterol
Why is the membrane described as asymmetrical
2 sides of the membrane have different compositions of glycolipids and phospholipids ans proteins
Where is the membarne produced
ER
What are glycoplipids
Lipids on the extracellular side of the plasma membrane which get a sugar group from the GA
What is the function of glycolipids on epithelial cells
Protect plasma membrane from harsh conditions- pH or enzymes
What is the function of glycolipids on nerve cells
Specialised type = ganglioslides (charged type of glycolipid)
Important for electrical effects
GM1 is a receptor for cholera
What is the function of glycolipids on lectins
Cell recognition
Viruses can bind
Why is an alpha helices a good shape for transport proteins through the membrane
They can slide against each other which selectively opens and closes channels
Why are beta barrels less specific transport proteins
Very rigid
Can’t yhdrgi conformational changes
Only have lids
