Help
Options
Didn't know it?
click below
click below
Knew it?
click below
click below
Don't Know
Remaining cards (0)
Know
retry
shuffle
restart
0:00
Embed Code - If you would like this activity on your web page, copy the script below and paste it into your web page.
Normal Size Small Size show me how
Normal Size Small Size show me how
Lipids and Membranes
Biochemistry, Medicine, Phase 1
| Term | Definition |
|---|---|
| Components of plasma membrane structure | hydrophobic regions, hydrophilic regions, proteins, glycoprotein, carbohydrate side chain |
| Carbohydrate side chain | will usually face out into the extracellular space |
| Membrane composition | varies according to cellular location |
| Carbohydrates only found in which membrane | plasma membrane; 8% |
| 1:1 protein protein:lipid ratio | plasma membrane, out mitochondrial membrane |
| 3:1 protein: lipid ratio | inner mitochondrial membrane; nuclear membrane |
| Most common lipid is cell membrane | phos/choline |
| Other lipids found in membranes (Varying degrees) | phos/serin, spingomyel, cholesterol, others |
| Lipids | insoluble in water, soluble in fat and organic solvents |
| Function of lipids | energy stores (triacylglycerol), precursor for vitamins and hormones, bile acids (cholic acid), membrane structure (phospholipids) |
| Phospholipids | essential and major component of all membranes; |
| Hydrophilic component of a phospholipid | composed of polar head group (serine, choline, ethanolamine, inositol) attached to a backbone of glycerol through a phosphate group |
| Hydrophobic component of a phospholipid | two fatty acyl side chains linked to the glycerol backbone via ester bonds |
| Amphipathic | phospholipids f.e.g; both polar and nonpolar components |
| Common head groups found in phospholipids | choline, serine, ethanolamine, inositol |
| Sphingomyelin | lacks a glycerol backbone; component of neural membrane of myelin; polar head is choline attached to the phosphate group; phosphate group directly attaches to ceramide which is connected to a fatty acyl chain (only one) |
| Shingosine | ceramide + fatty acyl chain |
| Glycerol backbone | CH2, CH, CH2 (across), two O down which attach to the fatty acid chains |
| Each glycerophospholipid | contains two fatty acids |
| Fatty acids can be | fully saturated, mono-unsaturated and poly-unsaturated |
| Fully saturated | no double bonds (number of carbon atoms in the fatty acid: number of double bonds) |
| Stearic acid | 18:0; 18 carbon atoms in fatty acid, no double bonds, SFA |
| Palmitic acid | 16:0; 16 carbon atoms in fatty acid, no double bonds, SFA |
| Myristic acid | 14:0; 14 carbon atoms in fatty acid, no double bonds, SFA |
| Mono-unsaturated | one double bond, MUSFA |
| Oleic acid | 18:1; 18 carbon atoms; 1 double bond, MUSFA |
| Poly-unsaturated | several double bonds |
| Arachidonic acid | 20:4; 20 carbon atoms, 4 double bonds; PUSFA |
| Delta | indicates position of double bonded in relation to the carboxyl group ; counting from the carboxyl terminal |
| Kink | produced by a double bond in a fatty acid |
| Cholesterol | hydroxyl group on cholesterol interacts with the polar head groups of the membrane phospholipids and sphingolipids; the bulky steroid and the hydrocarbon chain are embedded in the membrane, alongside the nonpolar fatty-acid chain of the other lipids. |
| Lipid bilayers are asymmetrical | two halves of the bilayer have different membrane composition |
| Phospholipids facing extracellular environment | phosphatidylcholine; sphingomyelin |
| Phospholipids facing intracellular environment | phosphatidylerserine, phosphatidylethanolamine |
| Generation of phospholipids | within the cell; requires an enzyme to get them in the right place in the membrane |
| Glycolipids | are lipids with a carbohydrate attached |
| Fluidity | the ease in which lipid molecules move about in the plane of bilayer - important in the regulation of membrane function (e.g. movement of proteins, signalling, exocytosis) |
| Regulation of fluidity | fatty acids are crucial regulators of fluidity, determined by chain length and degree of saturation |
| Short chain fatty acids | reduce the tendency of hydrocarbon chains to interact and hence increase fluidity |
| Kinks in unsaturated fatty acids | result in less stable van der Waals interactions with other lipids and hence inrease fluidity |
| High cholesterol | content restricts the random movement of polar heads, orders the lipid bilayer and decreases fluidity - rich in highly ordered regions of the membrane lipid rafts |
| Impaired fluidity | can damage cells; increased cholesterol content of red blood cell membranes is associated with severe liver diseases e.g. Cirrhosis |
| Abnormal cholesterol levels | when content of red blood cells is increased by 20-60% above normal, leading to decreased fluidity; alters cell shapes; impairs oxygen transport, destruction of red blood cells and anaemia |
| Structural cell membrane proteins | cell-cell contact, cytoskeletal organisation |
| Receptor cell membrane proteins | signal transduction and recognition |
| Ion channel cell membrane proteins | maintenance of ion gradients, transmission |
| Transporter cell membrane proteins | important and export substances |
| Enzyme cell membrane proteins | catalysis |
| Actin, spectrin, ankyrin | structural cell membrane proteins |
| Insulin receptor, glucagon receptor | receptor cell membrane proteins |
| Acetylcholine (nicotine), GABAa | ion channel cell membrane proteins |
| Glucose and glutamate transporters | transporter cell membrane proteins |
| Adenylyl cyclase | enzyme membrane proteins |
| Sramblase | |
| Integral (intrinsic) proteins | embedded in lipid bilayer, most span the entire bilayer; transmembrane spanning domains are either alpha helices or beta sheets; can span the membrane completely or not properly but are embedded within the membrane; channel or transporter |
| Anchored proteins | anchored to membrane by covalently bound fatty acids |
| Peripheral (extrinsic) proteins | attach to membrane surface by ionic interactions with integral proteins or with polar head group of phospholipids |
| Integral membrane protein (2) | |
| Anchored membrane proteins (2) | not deeply embedded in the bilayer by covalently linked to fatty acid chains (e.g. myristic or palmitic acid) or on the cell surface to a glycolipid |
| Alkaline phosphate | enzyme; example of a glycolipid anchored protein |
| RAS | example of fatty acyl anchored protein; signalling protein; relays information from the cell membrane |
| Peripheral proteins (2) | attach to the membrane surface by interactions with other membrane proeins or with the polar head group of phospholipids |
| Spectrin | important structural protein; on the cytoplasmic surface of erythrocytes; interacts with other proteins such as ankyrin |
| Phospholipase A2 | peripheral protein; binds to bilayer to cleave fatty acids from phospholipids |
| Sites of action of phospholipases | polar head (choline, ethanolomaine, myo-inositol) from phosphate group (PLD); phosphate group from glycerol backbone (PLC); remove the fatty acids (PLA1 - usually saturated), (PLA2, usually unsaturated) |
| High salt, urea treatment | removes peripheral proteins from the bilayer |
| Detergent (protein solution) | removes peripheral, anchored and integral proteins of the bilayer |
| Phospholipase | removes peripheral and anchored proteins of the bilayer; peripheral proteins (PLA, 2) |
| Detergents | are preferred method over organic solvents; like soaps; similar structure of phospholipids with a hydrophilic head and a hydrophobic tail; detergent monomers form detergent polymer micelles |
| Micelles | polymer of detergent monomers |
| Micelles + membrane proteins | results in water-soluble-lipid-detergent complex and water-soluble-lipid-detergent micelles; removing detergent and adding phospholipids back to proteins allows you to study your protein of interest and its function |
Created by:
emmaallde
Popular Biochemistry sets