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68 Cards in this Set
- Front
- Back
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do free ribosomes have membranes?
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no
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What are sugars extending on the extracellular surface of the cytoplasmic membrane a part of?
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glycocalyx
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What is the ratio of proteins to lipids in eukaryotic cell membranes?
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1:1
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What does amphipathic mean, and what membrane component exhibits this character?
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They have hydrophilic and hydrophobic domains
Phospholipids |
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What does a double bond do to hydrophobic tail structure?q
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introduces a kink
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What is a lipid micelle?
How many hydrophobic tails? |
A mono-layered phospholipid structure with hydrophobic compounds on the inside
Typical has a single hydrophobic tail |
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Why a spherical lipid bilayer more favorable?
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It keeps the hydrophobic inner layer from being exposed to water
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What do detergents do to membrane structure? What is this useful for?
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Disrupt the structure (hydrophilic head and a hydrophobic tail)
good for isolating proteins, and lipids from the cell membrane |
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What is the detergent CMC? and what does it determine?
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CMC: critical micelle concentration. if [detergent]> CMC then get micelles
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What does a strong detergent do to proteins, an example?
Example of a weak detergent? |
Denature proteins SDS
Triton X |
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Where are most lipids synthesized?
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Smooth ER
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Where does fatty acid degradation begin, and where?
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synthesis of fatty acyl CoA in mitochondria
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What is the precursor to triacylglycerol (fat)
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diacylglycerol
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What three components make up a phosphatidylcholine lipid?
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2 fatty acids, glycerol 3-phosphate, and choline
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What is zwitterionic?
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Has both positive and negative charges
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Which major phospholipid is not constructed from glycerol?
What is it important for? |
Sphingomyelin
insulation of nerve fibers |
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Which phospholipid carries a net positive charge?
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phosphatidyle serine
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What causes Neimann-Pick Disease? Presents as what type of deficiency?
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Deficiency of sphingomyelinase
neurological deficiencies |
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How long does it take for uncatalyzed flip/flopping of lipids in the membrane? What does a scramblase do? What about flipases and floppases generically? which requires energy?
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tens of minutes or days
- equilibrates lipid concentration across leaflets, energy independent - uphill lipid flipping, typically require ATP |
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What cell membrane things are glycolipids involved?
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cell recognition and adhesion
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Where are glycolipids predominantly found? and where are they generated?
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non-cytoplasmic leaflets of the plasma membrane
Golgi network |
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What is the charge of the inner leaflet of the plasma membrane? What causes this charge?
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(-), phosphytidylserine
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What binds to negatively charged phospholipids?
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Protein kinase C
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What membrane protein component does not flip?
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Integral membrane proteins
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What roles does lipid flip flop play?
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produces leaflet asymmetry leading to different events, or stop/start synethesis, or cell signalling
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What are the two signalling pathways that PIP2 is involved in?
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binding to a molecule and activating it.
can be degraded into two molecules that can activate signalling |
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What is target of over 50% of the current market for human therapeutics?
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GPCR- G protein coupled receptor. phosphatidylinoitol is involved in this
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Where can the inositol head group of phosphatidylinositol (PI) be phosphorylated at?
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3,4,5, and combination of all 1, or 2
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What are two potential effects of degradation of phosphatidylinositol?
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diacylglycerol activates protein kinase C
inosital releases Ca from endoplasmic reticulum |
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What are GPI anchored proteins and what is the benefit?
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Proteins that are anchored in the plasma membrane that are exposed to the extracellular space.
They all quick and easy release of the proteins when cleaved. Speeds release process |
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What are the three eicosanoids? What do they originate as? Where are they produced
Stored? half life? what are their actions mediated by? |
Prostaglandins, thromboxanes, and leukotrienes
1- polyunsaturated fatty acids with 20 carbons 2- produced locally 3- not stored, short half life 4- mediated by plasma and nuclear membrane receptors |
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What is the precursor of eicosanoids? where is it released from by phospholipase A2. what inhibits phospholipase A2?
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Arachidonic Acid
phospholipids hydrocortisone |
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What do leukotrienes do? Thromboxane A2, Prostacyclin?
Cell type origin of thromboxane and prostacyclin |
1- mediator of allergic response and inflammation
2- produced by activated platelets promotes clotting by promoting smooth muscle contraction and platelet adherence and aggregation 3- produced by vascular endothelial cells, inhibits clotting by stimulating vasodilation and inhibiting platelet aggregation |
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What does synthesis of TXA2 and Prostaglandins require? Details about the 2 isoforms
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COX 1- constitutive (always active and present
COX 2- inducible, the high prostaglandin levels induced by COX-2 result in pain,heat redness, and fever of infection |
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What do NSAIDS(nonsteroidal anti-inflammatory agents) like aspirin do to COX 1 &2? difference between high dosage and low dosage?
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Inhibits both
low doses thin blood (acetylates COX-1) inhibition can lead to damage of the stomach kidneys, and impaired blood clotting |
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What does celebrex do? What does it treat? side effects?
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Inhibits COX-2
treats arthritis, pain, menstrual cramps and colonic polyps causes heart problems, stroke, and blood clots |
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What does phospholipase C activated by and what does it play a role in?
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PIP2 system, and produces 2nd messengers
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What releases GPI-anchored proteins?
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Phospholipase C
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What does phospholipase A1 do?
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releases free fatty acids from lipids
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What does Phospholipase A2 do?
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releases arachidonic acid - precursor to prostaglandins
inhibited by glucocorticoids |
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What are the three lipid phases? Why is the last stage still ordered?
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Crystal, gel, liquid-crystalline
lipids are still oriented, heads face out, tails in |
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What does cholesterol do in the plasma membrane at low temp? at high temp? what lipid does it prefer?
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increases fluidity at low temperature, at high it stiffens the head group region thus decreasing solute permeability and decreasing fluidity (moderates)
sphingomyelin |
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What is a lipid raft? 2 things it is characterized by
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A detergent resistant lipid domain, characterized by high concentrations of sphingomyelins and cholesterol, thicker bilayer
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What is the purpose of the lipid raft?
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organize/localize membrane proteins for signalling purposes or transport, has many GPI-anchored proteins and proteins with one or more fatty acid or cholesterol molecules
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Main phospholipid in mitochondria?
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Phosphatidylcholine
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What are the two types of integral membrane proteins?
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alpha helical
beta sheet - aqueous channel |
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What do the graphed hydrophobicity peaks predict for alpha helix proteins, beta sheets/
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alpha - number of transmembrane helices
no peaks are in beta sheets |
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What is a characteristic of a peripheral membrane protein?
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Extractable with gentle procedures
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What are 4 types of peripheral membrane proteins association with the membrane?
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Hydrocarbon anchor
Electrostatic interaction partial membrane penetration association with integral proteins |
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What is the idea of cytoskeletal pickets?
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the idea that the cytoskeleton divides the membrane into compartments that all easily diffusion within, but which are hard to cross
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What is the membrane permeability coefficient? and what is the equation/
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Flux = permeability times the concentration difference
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What is membrane permeability determined by?
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hydrophobicity, and the size of the molecule
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What are the two types of gradients in a cell, and which is more powerful?
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electrical (membrane potential), and concentration
electrical is more powerful |
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Why is their an osmotic imbalance between cells and the ECM?
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Cells have a lot of negatively charged macromolecules that are balanced by a lot of positive counter ions. All the molecules cause water to be at a lower concentration and thus a gradient
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What is the solution of the osmotic problem within cells?
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Cells pump ions out to reduce the number of molecules in the cell and to reduce the osmotic pressure, leads to a slight positive charge outside
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What is the sodium potassium ATPase stoichiometry?
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3 Na+ pumped out, 2 K+ pumped in, and 1 ATP used
establishes the gradients |
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What type of solution is a crenated cell in? A swollen cell?
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Crenated - Hypertonic
Swollen - hypotonic |
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What is much much higher in the cell Na or K? Where is Cl highest?
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K, outside the cell
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Where is free calcium higher intracellularly or extracellularly?
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Extracellularly
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What does an aquaporin do?
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Transports water only down a concentration gradient, in areas that must have high water transport such as kidney, lungs, salivary glands
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What is a channel pore? a carrier?
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channel - simple hole, often selective, often gated
carrier- alters binding sites through conformation changes |
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What are 3 basic types of ion channel gates?
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Voltage gated, ligand gated, mechanical (sound in ear)
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What are the three types active carrier-mediated transport?
What is a passive tranpsort? |
Pump Na/K-ATPase, symporter down a concentration gradient, antiporter using a concentration gradient
uniporter |
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How is glucose transported into and out of cells?
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Into with a Na driven symporter, out the other side by passive diffusion
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What is Glut 1, where is it in highest levels, and what if there is a deficiency of it?
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The glucose transporter (a carrier protein and passive transporter)
High in erythrocytes and epithelial cells of BBB brain deficiency |
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What does the ABC stand for in ABC transporter? How does it work?
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ATP Binding Cassettes. Has a central compartment. ATP binds and closes it in. ATP is hydrolyzed, and it kicks out the molecule the other side
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What is the significance of multidrug resistance proteins?
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They are ABC transporters that kick out hydrophobic molecules like drugs, makes drug resistant. It is an advantage, cancer does it so does ome malaria
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What is the cause of cystic fibrosis?
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abnormal membrane Cl- permeability results in increased viscosity of bodily secretions. Usually Cl- flows out followed by Na+ and water which makes excretions more fluidy. By cystic fibrosis transmembrane regulator protein
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