20 terms

The Structure and Function of Biological Membranes

Properties of Lipids
Insoluble in water, soluble in fat and organic solvents
Functions: energy stores, precursors for vitamins and hormones, bile acids (cholic acids), membrane structure
Properties of Phospholips
Polar head group made up of serine, choline, ethanoline, inisol which are attached to the glycerol backbone by ester bonds
Amphipathic - possess both hydrophobic and hydrophilic regions
Found in myelin sheaths, lacks a glycerol backbone
Saturated fatty acids
Stearic acid (18,0), Palmatic acid (16,0), Myristic Acid (14,0)
Monounsaturated fatty acid
Oliec acid (18,1)
Poly unsaturated
Aranchadonic acid (20,4)
Phospholipids facing extracellular environment
Phosphatidyl choline and sphingomyelin
Phospholipids facing intracellular environment
Phosphatidylserine and phophatidylethanolamine
Factors that increase fluidity of cell membranes
Increase in proportion of short chain fatty acids and unsaturated fatty acids
Factors that reduce fluidity of cell membrane
Cholesterol. (In cirrhosis cholesterol content of the RBCs increase by 20 - 60 % which alters cell shape, impairs oxygen transport and causes erythrolysis and anaemia
Function and examples of structural protiens
Cell to cell contact, cytoskeletal organisation
Eg: actin, spectrin
Function and examples of receptor protiens
Signal recognition and transduction
Eg: Insulin receptor
Function and examples of ion channels
Maintenance of membrane potentials, transmission of action potentials
Function and examples of transport protiens
Import/ export of substances
Eg: Glut transporters
Function and examples of enzymatically active protiens
Catalyse reactions
Eg: Adenylate cyclase
Anchored Proteins
Covalently bound to phospholipids
Extrinsic Protiens
Ionic interactions with phosophlipids and intrinsic protiens
Treatment of high salt/ urea protein test
Peripheral- Removed, Anchored-stay , Integral- stay
Treatment of Detergent - protein test
Peripheral removed, Anchored removed, Integral, removed
Treatment with phospholipase
Peripheral removed, Anchored stay, Integral stay