Membrane Flashcards
Functions of membrane
Signaling, transport, growth, motility, form organelles/compartments
Thickness of lipid bilayer
8-9 nm
Why does lipid bilayer form compartments?
Edges are energetically unfavorable, membrane will spontaneously form spheres and self-seals if broken
Selective permeability
Allows through small hydrophobic and uncharged molecules, larger, polar and charged particles require specific transport
Effect of saturation on membrane
Unsaturated fatty acids pack less densely and allow more fluidity, saturated chains decrease fluidity
Effect of cholesterol on membrane
Stiffens to distortion, decreases fluidity overall
Extracellular phospholipids
High in phosphatidylcholine, sphingomyelin, glycolipids
Intracellular phospholipids
Phosphatidylserine, phosphatidylethanolamine
How is membrane asymmetry maintained?
Lipids are generally added to cytosolic side, specific flippase can transfer to other half
Production of glycolipids
Produced in lumen of Golgi -> vesicle -> external layer (usually remain outside to form glycocalyx)
Categories of membrane proteins (4)
Transmembrane, monolayer, lipid linked, protein attached (integral includes trans and monolayer, peripheral is linked to lipid or protein)
Functions of transmembrane proteins (5)
Transport, receptors, anchors, enzymes, structural
Glycoprotein vs proteoglycan
Long carbohydrate chain is proteoglycan vs short chain is glycoprotein
Structural membrane proteins
Link membrane to cell, ex spectrin holds RBCs in shape
Function of glycocalyx
Mostly for recognition, ex lectin induces neutrophil migration during an infection
