Membrane Bilayer Structure: Lipids Flashcards
What are the major function of biological membranes?
Continuous, highly selective permeability barrier. Control of the enclosed electrochemical environment. 1- Recgonition, 2- Signalling, 3-Adhesion proteins, 4- Immune Surveillance, signal generation in response to stimuli.
What are epithelial cells membrane specialised for?
Interaction with basement membrane interaction with adjacent cells, absorption of body fluids, secretion and transport
What do membranes contain, by dry weight?
40% lipid, 60% protein, 1-10% carbohydrate (can be glycoproteins or glycolipids)
What are lipid membrane constituents?
Phospholipids, glycolipids and cholesterol
What does lipid amphipathicity mean?
One part of the molecule is hydrophilic and another part is hydrophobic.
What are the 3 parts of glycerophospholipids?
Polar group (hydrophilic head), glycerol ‘backbone’, fatty acid chains (hydrophobic tail).
What’s the difference between saturated and unsaturated?
Saturated- no C=C bond in fatty acid chains, unsaturated- one C=C bond in one fatty acid chain.
What is sphingomyelin?
It is a phospholipid but has no glycerol backbone.
What are the common structural features of membrane lipids- fatty acid?
Amphipathic: hydrophilic head and a hydrophobic tail. The tails are unsaturated and saturated.
What is the role of cholesterol in lipid membrane?
It acts as a buffering molecule preventing abrupt changes in membrane fluidity over a range of temperatures.
Role of water in cell membranes.
Provides the environment for membrane formation, is also a highly dynamic structural component of living cell membranes.
Role of lipid rafts.
Stabilising and organising proteins, it acts as organising domains for receptors and signalling molecules. Optimises kinetic interaction for signal transduction.
