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116 Cards in this Set
- Front
- Back
- 3rd side (hint)
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Being polar on one end and non-polar on the other is...
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amphipathic
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ex: detergents, cholesterol, phosphatidylcholine
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what is a fatty acid?
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aliphatic and amphipathic, can be saturated or unsaturated, have a hydroxyl head with a hydrocarbon chain
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what is a triglyceride?
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esters of fatty acids with glycerol, hydrophobic
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what are sphingolipids?
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Lipids with a variety of carbohydrates attached
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what is a phospholipid?
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Like triglycerides but the third position of glycerol has a phosphate attached with a polar head group attached through a phosphodiester bond.
They are amphipathic |
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what are the 2 ways to synthesize phospholipids?
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activate the head group first or the diacylglycerol first
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what are 4 functions of phospholipids?
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1.Membrane components
2. signaling molecules 3.surfactant 4.platelet activating factor |
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what are 2 signaling functions of phospholipids?
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phosphotidylinositides and aracidonic acid metabolism
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How does phosphatidylinositol make DAG and IP3?
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PI is phosphorylated by PI kinase into PIP, this is then phosphorylated by PIP kinase into PIP2, the PIP2 is hydrolyzed by PLC into DAG and IP3
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what is surfactant?
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phospholipids and proteins
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what makes up a cholesterol?
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polar head, steroid nucleus and alkyl side chain
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Describe the steps in cholesterol synthesis?
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3 acetyl CoA's combine, then the rate limiting step(reduction) makes mevalonate, 3 phosphate groups are added to make isoprene, then 6 activated isoprenes make squalene, this is cyclized to cholesterol
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what are the different lipid transport molecules called?
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chylomicrons
VLDL's IDL's LDL's HDL2 and 3 |
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How is cholesterol disposed?
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By bile acids or free cholesterol
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what do cholystyramines do?
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bind to bile acids and prevent reabsorption
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what are eicosanoids?
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prostaglandins and related compounds
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What are the functions of Apo A,B,C and E?
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A=activation of LCAT(to esterify the cholesterol)
B=receptor binding C=LPL activator(to transfer lipids) E=remenant receptor binding |
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what makes corticosteroids anti-inflammatory?
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prevent inducible Phospholipase A2 expression, reducing arachidonate release
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What are highly specialized proteins with extraordinary catalytic power and a high degree of specificity for substrates?
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Enzymes
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inorganic ions required by some enzymes for catalytic action
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cofactors
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complex organic or metallo-organic molecules required by some enzymes for catalytic action
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coenzymes
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coenzyme or metal ion covalently bound to enzyme
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prosthetic group
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the complete catalytically active enzyme complex along with the bound coenzyme
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holoenzyme
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catalytically inactive protein part of the enzyme without the prosthetic group
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apoenzyme/apoprotein
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area on enzyme containing the amino acid side chains that are involved in catalyzing the reaction.
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active site
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the molecule that is bound in the active site and is acted on by the enzyme to form product.
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substrate
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what are the 2 distinguishing features of an enzyme catalyzed recation?
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1. it only takes place within the active site
2.the molecule bound selectively and acted upon by the enzyme is the substrate |
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the starting point for either a forward or reverse chemical reaction
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ground state
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when the molecules raised to a higher energy level reach the top of the energy hill, there is a point at which decay to the S or P state is equally probable.
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transition state
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the difference between the energy levels of the ground state and the transition state
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activation energy
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a higher activation energy corresponds to a (faster/slower) reaction?
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slower
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2 ways reaction rates can be increased?
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1. increase temp
2.lowering activation energy |
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what is the rate limiting step in a reaction?
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the one with the highest activation energy
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how do enzymes contribute to life?
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selectivity and efficiency of reactions
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what is binding energy?
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energy released when substrate binds to active site in formation of ES complex
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what is the major source of lowering activation energy?
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binding energy
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molecular agents that
interfere with catalysis, slowing or halting enzymatic reactions. |
enzyme inhibitor
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how does a competitive inhibitor interfer with a reaction?
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it competes with the substrate for the active site, it is overcome by adding more substrate(reversible)
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how does a non-competitive inhibitor interfer with a reaction?
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it binds covalently(irreversibly)or destroys a functional group in the active site, unable to be overcome by adding more substrate
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a special class of irreversible
inhibitors. They are relatively un-reactive until they bind to the active site of a specific enzyme. |
suicide inactivator
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what is maximum velocity?
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the point at which all active sites are filled with substrate
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what is Km?
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the concentration of substrate that produces half max velocity
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How does competitive inhibition affect Vmax and Km?
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Vmax stays the same, Km is increased
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How does non-competitive inhibition affect Vmax and Km?
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Vmax is lowered and Km stays the same
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Enzymes that undergo conformational changes
induced by the binding of modulators |
allostreic enzymes
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what are allosteric modulators?
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usually small metabolites or cofactors
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what are homo/heterotropic regulatory enzymes?
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homo=substrate and modulator are the same
hetero=substrate and modulator are different |
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what is feedback inhibition?
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when the end product of a reaction inhibits(turns off) regulatory enzymes
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what are 2 ways of modulating regulatory enzymes?
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1. reversible non-covalent binding of modulators(allosteric enzymes)
2. reversible covalent modification(phosphoralation) |
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what is the function of protein kinases?
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attach phosphoryl group to amino acid residue on regulatory enzyme(the glue)
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what is the function of protein phosphatases?
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removes the phosphoryl group from the regulatory enzyme(the scissors)
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what is the difference between a micelle, bilayer and liposome?
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micelle is single layer lipid "tube", liposome is a bilayer lipid "tube" which entraps water in the center of the tube
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Glycerol molecule with a phosphate esterified at the a-carbon with two long-chain fatty acids
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glycerophospholipids
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carbohydrates that attach to proteins to form glycoproteins
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membrane carbohydrates
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what are the 3 major lipid components of eukaryotic membranes?
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glycerophospholipids, spingolipids, cholesterol
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what are 4 ways that phospholipids move?
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1. lateral diffusion
2. hydrocarbon chain flexing 3. rotational diffusion 4. transverse exchange |
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what promotes the transverse movement of lipids from one layer to another?
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lipid transporter
ex:flippase |
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List 6 examples of things that can affect lipid fluidity
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1. temperature
2. phospholipid composition 3. head size/charge 4. cis double bond 5. cholesterol 6. fatty acid length |
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These membrane proteins have sequences of hydrophobic amino acids, which create hydrophobic domains that interact with the hydrophobic hydrocarbons of the lipids and stabilize the protein–lipid complex. They need a detergent or organic solvent to be released from the membrane.
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integral/intrinsic proteins
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These proteins are released by treatment with salt solutions of different ionic strength or extremes of pH and are typically water soluable
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peripheral/extrinsic proteins
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what is the difference between a channel and a pore for facilitated movement through a membrane?
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pores are non-selective for inorganic and organic molecules but channels are selective for inorganic anions and cations
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an area of varying size where the plasma membranes of neighboring cells are separated and can open and close
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gap junction
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how is a pore formed?
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Alignment of connexons from each cell across the gap junction. several cells combine to form the pore
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hormonal stimulation of one cell can lead to signal propagation to a cluster of cells.
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metabolic coupling through gap junctions
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Depolarization of one group of muscle cells rapidly spreads to adjacent cells
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electrical coupling through gap junctions
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How does a voltage gated channel work?
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voltage gated channels sense electrical gradients and selectively filter based on amino acid residues lining the channle area and the size of the open area
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How does a ligand gated channel work?
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when the receptor sites are occupied, the channel opens allowing diffusion of ions
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How do membrane transporters work?
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they physically bind to a molecule and carry it across the membrane
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What is the difference between facilitated and active transport?
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facilitated transport occurs passively down a gradient and active transport requires energy to move the solute
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How does uniport differ from symport and antiport?
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symport and antiport are cotransporters, symport requires the solute to be carried along with another molecule and antiport requires an exchange of molecules, uniport moves solute alone across the membrane
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How do primary and secondary active transport differ?
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primary transport moves a solute across one membrane either in or out of the cell, secondary transport moves the solute through the cell via 2 separate membrane transporters
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what is group translocation?
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when molecules such as amino acids are modified in order to transport across the membrane, large energy expenditures required
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List 5 functions of lipids
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1. energy source
2.structural components of cell membranes 3. chemical messengers 4.vitamin absorption and transportation 5. shock absorber to protect organs and insulate from temp extremes |
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How do saturated and unsaturated fatty acids differ structurally?
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saturated FA's are straight and unsaturated FA's have a kink in the chain
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What are the 4 products in phosphatidylcholine synthesis?
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1.choline
2. phosphocholine 3. CDP-choline 4. phosphatidylcholine |
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What are the enzymes that act on the 4 products during phosphatidylcholine sysnthesis?
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1. choline kinase
2. CTP choline cytidylyl transferase 3.CDP-choline diacylglycerol phosphocholine transferase |
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Which kind of fatty acid has greater fluidity, saturated or unsaturated?
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unsaturated
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What does IP3 do?
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activates the ligand gated Ca channel for slow release of Ca
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What does DAG do in the cytosol?
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combines with Ca released by IP3 to activate protein kinase C
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How is PAF(platelet activating factor) made?
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sysnthesized and released from activated immune cells
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Where are the receptors for PAF?
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on the lipid layer of the cell
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How does PAF work?
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it activates PLC and PLA2 and can aggregate platelets
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What is the precursor to all steroid hormones except estradiol?
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cholesterol
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In what form is most of the cholesterol in the body?
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cholesterol esters
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Why is cholesterol esterified?
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to help in transport between cells so it isn't taken back up by the cell it came from
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Where does cholesterol synthesis take place?
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in the liver
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Where do statins work?
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at the rate limiting step, HMG Co-A reductase conversion to mevalonate
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Which is the largest cholesterol transport mechanism?
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chylomicrons
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Where are each of the following made?
chylomicrons, VLDL, LDL, HDL |
chylomicrons-small intestines
VLDL-liver LDL-from IDL(which is made from VLDL degredation) HDL-liver and intestine |
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What is the primary function of each of the following?
chylomicron, VLDL, LDL, HDL |
chylomicron-transport dietary lipids
VLDL-transport endogenous triglycerides LDL-cholesterol transport HDL-reverse cholesterol transport |
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Which apoprotein does HDL have that the others do not and what is it's function?
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Apo A, it activates LCAT to esterify the cholesterol so it can't move back into the tissue cell it was taken from
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How are LDL's removed from the blood?
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bind to apo b recpetor site and taken into cell by endocytosis. Broken down by lysosome into AA's FA's cholesterol droplets and the receptor and are recycled.
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How are apo B receptors synthesized?
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by the ER of the cell, packaged by golgi and transported to surface for use
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Which is the "bad" cholesterol for CV health, LDL or HDL?
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LDL
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What are 2 ways to lower total cholesterol?
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statins (decrease synthesis)and cholysteramines(increase removal)
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What effect does insulin and glucagon have on cholesterol synthesis?
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insulin actiavtes while glucagon inactivates the HMG Co-A reductase in cholesterol synthesis, therefore, insulin=increase cholesterol
glucagon=decrease cholesterol |
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What effect does free cholesterol levels have on cholesterol regulation?
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higher free cholesterol levels (in the cell)
1.inhibit ACAT (enzyme)formation of cholesterol esters 2. inhibit uptake of cholesterol from extracellular sources 3. feedback inhibition of HMG Co-A reductase in synthesis of new cholesterol |
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Why are ecosinoids considered "local hormones"?
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They act on target cells close to their site of formation and they are broken down quickly so they do not travel far.
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prostaglandins, thromboxanes, and leukotrienes are all...
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eicosanoids
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What is PLA2's role in the synthesis of eicosinoids?
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it cleaves the AA from the membrane phospholipid
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What is the impulse conduction on a myelinated sheath called?
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saltatory conduction
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What does the nernst equation defune?
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The relation of the diffusion potential to the concentration difference of an ion
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What does propagate mean?
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conducted without reduction
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What are characteristics of action potentials?
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1. all or nothing events
2. constant amplitude 3. initiated by depolarization 4.involve changes in membrane permeability 5. rely on voltage gated channels |
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What state are the channels in during resting membrane potential?
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the activation gates are closed and the inactivation gates are open
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What state are the channels in during depolarization?
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voltage gated Na channels are open and voltage gated K channels start to open
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what state are the channels in during repolarization?
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voltage gated Na channels are closed and voltage gated K channels are open
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What state are the channels in during end repolarization and afterpotential?
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voltage gated Na channels are closed, diffusion of K produces afterpotential
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Can a action potential initiate depolarization during the absolute refractory period?
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No
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How does action potential depolarization during the relative refractory period affect the threshold?
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lower threshold until after relative refractory period is complete
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List 4 functions of action potentials?
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1. info delivery to CNS
2. info encoding 3. rapid transmission over distance 4. initiators of cellular responses in non-nervous tissue |
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What makes perkinjie and pacemaker cells different from nerve cells related to action potential?
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They rely on Ca channels asopposed to Na channels for their action.
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What channels are located in the subneural cleft of a NMJ?
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Ach gated channels at the top and voltage gated Na channels on the bottom
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Describe the 4 steps in transmission of action potential at NMJ motor end plate.
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1. action potential causes voltage gated Ca channels to open
2. Ca in presynaptic terminal causes release of Ach 3. Diffusion of Ach to post-synaptic muscle fiber causing inc permeability of ligand gated Na channels 4. Na permeability results in depolarization |
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What happens to Ach after it's use on post-synaptic receptors?
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AchE breaks it down and the choline is taken back up by pre-synaptic cell to be recycled into more Ach
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What is the function of Mg on the RYR1 receptor?
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Mg attached to high and low affinity binding sites keeps Ca channels closed
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