Lipids and membrane structures Flashcards
Definition of lipids
Insoluble in water, soluble in fat/organic solvents. Energy state, precursors for vitamins, steroid hormones, bile acids and phsopholipids
Definition of fully saturated
No C=C in FA
Definition of unsaturated
1 C=C in FA
Definition of polyunsaturated
Many C=C in FA
Definition of phospholipases
Important class of enzymes that bind to membrane and selectively hydrolyses components of phospholipids
Structure of a triglyceride
Ester of 3 FA/glycerol
How to form and hydrolyses triglyceride
Dehydration/synthesis
Hydrolysis
Structure of a fatty acid
Long chain aliphatic carboxylic acids
Metabolised via B-oxidation pathway => ATP generation
Naming unsaturated triglycerides
(18:1 ∆9)
No of C in chain
No of C=C
Position of C=C in relation to COOH
Describe the fluid mosaic model of membrane structure
Thickness of membrane
Islands of proteins in a sea of lipid
4-5nm
Structure of a phospholipid
PO3 2- and serine/choline/ethanolamine/inositol
Glycerol
2 FA
Structure of a glycolipid
Carbohydrate
Glycerol
2 FA
Properties of phospholipid
Bilayer in aqueous environment Polar head group (PO3 2- serine, choline, ethanolamine, inositol) 2FA side chains Ester bond to glycerol, hydrophobic Amphipathic
Structure of sphingomyelin
Choline
Phosphate
Ceramide Sphingomyelin
Fatty acyl chain
Features of the lipid bilayer
Asymmetrical
Very fluid, ease which lipid molecules move about, don’t move from 1 plane to another
Regulation of fluidity
Lipid composition of membrane defines fluidity
Increased SCFA, decreased VDW, increased fluidity
Increased UFA, decreased VDW, increased fluidity
Increased cholesterol, decreased random movements of polar heads, decreased fluidity
Structure of a lipid raft
Specialized membrane micro domain
More ordered, less fluid, section of limited movement
Increased cholesterol and sphingomyelin
Allows close interaction between receptors and signaling molecules
Types of membrane protein
Structural Receptors Ion channels Transporters Enzymes
Function of structural proteins
Cell-cell contact, attachment of cytoskeleton
Function of receptor proteins
Signal recognition and transmission
Function of ion channel proteins
Maintenance of ionic gradients and transmissions
Function of tranporter proteins
Import and export of substrates
Function of enzymes
Catalysis
Organization of membrane proteins
Integral/intrinsic proteins
Anchored proteins
Peripheral/extrinsic proteins
Properties of integral proteins
Embedded in bilayer
Most are transmembrane, spanning domains=a helices, b sheets
Properties of anchored proteins
Anchored to membrane by covalent bonds with FA
Properties of peripheral proteins
Attach to membrane surface by ionic interaction with integral proteins or with polar head groups of phospholipids
Types of phospholipases
Phospholipase A1 (Ester between FA and G) Phospholipase A2 (Ester between FA and G) Phospholipase C (Ester between G and PO3 2-) Phospholipase D (Ester between PO3 2- and polar head)
High salt/urea treatment on peripheral, anchored and integral proteins
Removed
Remain
Remain
Detergent treatment on peripheral, anchored and integral proteins
Removed
Removed
Removed
Phospholipase treatment on peripheral, anchored and integral proteins
Removed/Remain
Removed
Remain
Detergent action of bilipid layer
Detergent molecules completely disrupt lipid structure, whole thing falls apart, can isolate proteins
