Term
| Enzymes are neither _____ nor _______ during reactions, because they are biological __________. |
|
Definition
| formed, consumed, catalysts |
|
|
Term
| Most enzymes are _________, but some are ______ _______ such as __________. |
|
Definition
| proteins, nucleic acids, rRNA |
|
|
Term
| Enzymes significantly enhance the rate of reactions, by sometimes as much as ______. |
|
Definition
|
|
Term
| What enzyme catalyzes the dissociation of CO2 in H2O? |
|
Definition
|
|
Term
| Even though this reaction can occur spontaneously, how much faster does dissociation of CO2 in H2O happen in the presence of its catalyst? |
|
Definition
|
|
Term
| What value/unit of measure is used to rate the efficiency or productivity of an enzyme? |
|
Definition
|
|
Term
| What units does turnover number use? |
|
Definition
| How many molecules of reactant an enzyme can convert to product per second |
|
|
Term
| What is a proteolytic enzyme? |
|
Definition
| An enzyme that cleaves peptide bonds |
|
|
Term
| DNA polymerase has an error rate of? |
|
Definition
| 1 out of every 10^8 base pairs - very specific recognition capability |
|
|
Term
| What is one characteristic about substrates that allows enzymes to be so specific? |
|
Definition
| substrate stereochemistry - enzymes are stereospecific in that they often only recognize L conformers, and ignore D conformers |
|
|
Term
| What is one way enzyme activity is regulated? |
|
Definition
| Activation - many enzymes are produced in their inactive form and must be activated by some other mechanism |
|
|
Term
| What is the inactive form of Trypsin? |
|
Definition
| Trypsinogen - another enzyme cleaves a specific peptide bond, cutting trypsin into two parts, making one of the newly formed polypeptides an active form of trypsin |
|
|
Term
| What is covalent modification used for? |
|
Definition
| Regulation of enzyme activity |
|
|
Term
| Phosphorylation can either _______ or _______ enzyme activity, depending on the enzyme's conformation. |
|
Definition
|
|
Term
| What functional group among amino acids is often phosphorylated in order to regulate enzyme activity? |
|
Definition
| -OH groups - tyrosine, serine, and threonine |
|
|
Term
| What is feedback inhibition? |
|
Definition
| Regulation of enzyme activity by the resultant product of the enzyme's activity coming and binding to the enzyme when the product is in excess, thereby inhibiting the enzyme's activity |
|
|
Term
| Reversible inhibition falls into two types: |
|
Definition
| Competitive and noncompetitive |
|
|
Term
| What is competitive inhibition? |
|
Definition
| a molecule that is structurally similar that binds to the active site in an enzyme, "competing" for the active site with the substrate, thus inhibiting the enzyme from forming product |
|
|
Term
| What is noncompetitive inhibition? |
|
Definition
| a molecule that binds to a site on an enzyme that is not on the active site. so, regardless of whether the substrate concentration is in excess or not, the enzyme's activity is inhibited |
|
|
Term
| Which kind of inhibition can be remedied by increasing substrate concentration? |
|
Definition
| Competitive - if the mechanism acts competitively, then the molecule that is most concentrated will beat out the inhibitor substrate and thus the inhibition will be rememdied and enzyme activity will be restored |
|
|
Term
| What is a competitive inhibitor for the succinate ion? |
|
Definition
|
|
Term
| How does sulfanilamide work? |
|
Definition
| competitive inhibitor for an enzyme in bacteria that converts PABA into folic acid, thereby retarding bacterial growth. this does not affect mammals (hosts) b/c mammals absorb folic acid through their diets |
|
|
Term
| How is effectiveness increased in competitive inhibition when synthesizing antibiotics? |
|
Definition
| greater diversity - bacteria reproduce very quickly, so they are able to mutate and survive antibiotic treatment. so, providing greater diversity puts up roadblocks for mutations that will allow bacteria to survive |
|
|
Term
| How does methotrexate work? |
|
Definition
| binds 1000-fold more tightly (competitive inhibition) than tetrahydrofolate, the normal substrate, to the dihydrofolate reductase, which assists in the biosynthesis of purines and pyrimidines. it reduces nucleotide synthesis, and thus it inhibits DNA replication and can help treat cancer |
|
|
Term
| What is tetrahydrofolate? |
|
Definition
| it is the normal substrate for dihydrofolate reductase, the enzyme that assists in purine and pyrimidine synthesis, thus facilitating DNA replication by providing new nucleotide bases |
|
|
Term
|
Definition
| the Km of a competitive inhibitor for a given enzyme |
|
|
Term
| The lower the Km value, the greater the _________ for enzymes and substrates. |
|
Definition
|
|
Term
| The higher the Km value, the lower the ___________ for an enzyme and substrate. |
|
Definition
| affinity - Km and enzyme affinity for substrate have an inverse relationship |
|
|
Term
| What is an experimental way of determining whether an inhibitor is competitive or noncompetitive? |
|
Definition
| if a sample has a given amount of enzyme, then adding a given amount of inhibitor, by adding an increasing amount of substrate will tell you which - if Vmax can be achieved, then the inhibitor is competitive. if it is noncompetitive, then Vmax cannot be attained. |
|
|
Term
| How do irreversible inhibitors [often] bind to enzymes? |
|
Definition
| they make covalent linkages to amino acids at the active site in the enzyme - this is toxic to the cell |
|
|
Term
|
Definition
| diisopropylphosphofluoridate - has a F substituted for an -OH group on a phosphate, making it highly reactive - forms an ester linkage with a serine |
|
|
Term
|
Definition
| makes covalent linkage to cysteine residues |
|
|
Term
| How does penicillin work? |
|
Definition
| irreversible inhibitor that acts on bacterial transpeptidase. |
|
|
Term
|
Definition
| strengthens bacterial walls by forming peptide bonds between D-amino acids that cross link peptidoglycan structure, facilitating cell growth. so, if you inactive this enzyme, then the cell cannot grow and divide |
|
|
Term
| Why does penicillin not kill mammallian cells? |
|
Definition
| because MOST of our amino acids are the L enantiomer and the bacterial are D enantiomers |
|
|
Term
| Penicillin contains a beta-_______ ring (cyclic amide) fused to a ___________ ring. |
|
Definition
| lactam, thiazolidine - the 4-membered ring in the beta-lactam is highly reactive |
|
|
Term
| Penicilan forms what kind of linkage with what amino acid in the active site? |
|
Definition
| ester linkage, nucleophilic attack, serine |
|
|
Term
| What was the first penicillin that was stable in acidic conditions, and thus able to withstand oral ingestion? |
|
Definition
| Penicillin V - has a phenoxymethyl group on it - resonance stabilization |
|
|
Term
| What does PenVK stand for? |
|
Definition
| Penicillin V, Potassium salt - the COOH group gets a K+ associated with the O-, making it more soluble |
|
|
Term
| If you have an allergy to penicillin, are you able to take any other "cillins"? |
|
Definition
| no, if the person has an allergy to the beta-lactam ring or any other aspect of the "cillin" part of the antibiotic, then they cannot take it. |
|
|
Term
| Enzymes utilize what 4 rxns for catalysis? |
|
Definition
| acid/base, covalent, metal ion, alignment (approximation) |
|
|
Term
| Additional free energy is obtained through the _______? |
|
Definition
|
|
Term
| How can enzyme mechanisms be "visualized"? |
|
Definition
| X-ray crystallography/NMR, and chemical modification of active sites gives insight to what groups participate |
|
|
Term
| Genetically engineered enzymes can be used for what? |
|
Definition
| chemical modification for enzyme mechanism "visualization" |
|
|
Term
| Lysozymes use what kind of catalysis? |
|
Definition
|
|
Term
| Carbonic anhydrase uses what kind of catalysis? |
|
Definition
|
|
Term
| Lysozyme acts by cleaving _____________ that give structural integrity to bacterial cell walls |
|
Definition
|
|
Term
| Cell wall polysaccharides are composed of two kinds of glucose derivatives connected by what? |
|
Definition
|
|
Term
|
Definition
|
|
Term
|
Definition
|
|
Term
| Chitin has what kind of polysaccharide beta 1-4 linkage? |
|
Definition
|
|
Term
| What type of interaction brings the NAG-NAM hexamer into the active site of the enzyme? |
|
Definition
|
|
Term
| Between what two sites of the NAG-NAM hexamer is the molecule cleaved? |
|
Definition
|
|
Term
| How does an enzyme's active site have a different pH than physiologic pH? |
|
Definition
| A microenvironment is created, so isolated regions of the enzyme may have different pH, allowing for protonation of some residues and not others |
|
|
Term
| the enzyme cleaves the D-E NAG-NAM bond by __________ ________ on the -0H of the active site, deprotonating the -OH on the enzyme and donating that proton to the E residue, making it a leaving group |
|
Definition
|
|
Term
| Optimum pH for Lysozyme is? |
|
Definition
|
|
Term
| AT a pH>5, Glu-35 ______ and cannot supply the hydrogen ion required for cleavage |
|
Definition
|
|
Term
| For carbonic anhydrase, the limiting factor is what? |
|
Definition
| how fast the substrate (CO2 and H20) can diffuse into the active site (demonstrating how fast and efficient this enzyme is) |
|
|
Term
| WHat metal cofactor helps water prepare for formation of carbonic acid? |
|
Definition
|
|
Term
| Zinc reduces the pKa for water from 15.7 to what? |
|
Definition
|
|
Term
| The 3 residues bound to the Zinc in carbonic anhydrase are what? |
|
Definition
|
|
Term
| What residue on carbonic anhydrase shuttles the build-up of H+ ions in bicarb formation? |
|
Definition
|
|
Term
| Serine proteases act in what manner to cleave bonds? |
|
Definition
| as strong nucleophiles attacking carbonyl carbon in peptide bonds - (the OH on the functional group) |
|
|
Term
|
Definition
| catalyzes the hydrolysis of peptide bonds following amino acids with large, bulky nonpolar groups (no charge) hence its lack of specificity |
|
|
Term
| Chymotrypsin can be tricked into hydrolyzing a synthetic substrate that releases a highly colored substrate such as what? |
|
Definition
| p-nitrophenol - for study in the lab |
|
|
Term
| For chymotrypsin, Ser-195 attacks substrates forming what kind of linkage? |
|
Definition
|
|
Term
| After Ser-195 forms an ester linkage to a substrate, water enters and does what? |
|
Definition
| deacylates the enzyme by hydrolyzing the ester bond |
|
|
Term
| For chymotrypsin's action, which step of the reaction is rate-limiting? |
|
Definition
| hydrolysis of the ester bond |
|
|
Term
| How was the rate-limiting step determined for chymotrypsin? |
|
Definition
| Burst-phase kinetics = once all enzymes have been acylated, they wait for water to release the substrate and this can be measured with special instruments |
|
|
Term
| In burst phase kinetics, increasing the enzyme and substrate concentration will produce what on the absorbance plot? |
|
Definition
| a steeper and longer burst phase, but once they are all acylated, then the steady state is again attained |
|
|
Term
| For the serine in chymotrypsin, how do you achieve a stronger nucleophile? |
|
Definition
| the carboxyl group is negatively charged, drawing the h- off of the histidine, and then the histidine draws the h- off of the hydroxyl group of the serine. thus, resonance provides a more negative charge on the hydroxyl (alkoxide if fully deprotonated), making it a stronger nucleophile |
|
|
Term
| for chymotrypsin, once the resonance form has made the alkoxide on the serine (making a stronger nucleophile), then what happens? |
|
Definition
| the alkoxide oxygen reaches for the carbonyl carbon of a substrate, making an ester linkage (nucleophilic attack) |
|
|
Term
| the newly formed enzyme-substrate anion is called what for chymotrypsin? |
|
Definition
|
|
Term
| what does the production of an oxyanion achieve in catalysis in chymotrypsin? |
|
Definition
| lowered energy of activation |
|
|
Term
| BE ABLE TO DRAW SLIDE 34 OF ENZYME MECHANISMS |
|
Definition
| BE ABLE TO DRAW SLIDE 34 OF ENZYME MECHANISM |
|
|
Term
| How do different serine proteases (having the same mechanism) have different specificities? |
|
Definition
| a separate "pocket" with different amino acid side chains providing the diversity |
|
|
Term
| how do chymotrypsin and trypsin differ? |
|
Definition
| chymotrypsin has just the serine providing for specificity, whereas trypsin has an asp-189 with a negative charge, attracting positively charged substrates (arginine and lysine) |
|
|
Term
| Where are chymotrypsin and trypsin synthesized? |
|
Definition
| pancrease - inactive form |
|
|
Term
|
Definition
| a serine protease that is synthesized and stored in an inactive form in high concentrations in granules until they are summoned by the body |
|
|
Term
| What is the inactive precursor to chymotrypsin/trypsin? |
|
Definition
|
|
Term
| Crystalline, inactivity, and storage in granules are they body's mechanism for what? |
|
Definition
| protecting our tissues from enzymatic attack |
|
|
Term
| pi-chymotrypsin does what to activate trypsin? |
|
Definition
| binds to inactive chymotrypsinogen and cleaves it between 15 and 16 residues |
|
|
Term
| What is a 4th way that the body protects itself from proteolytic attack on its own tissues? |
|
Definition
| synthesizing competitive inhibitors |
|
|
Term
| How does the body's competitive inhibitor inhibit serine proteases? |
|
Definition
| it turns the histidine out of plane, impeding the flow of electrons forming resonance structures, so the alkoxide ion cannot form, inactivating the serine residue. |
|
|
Term
| Upon entering the duodenum, how is the inhibitor removed from the serine protease? |
|
Definition
| dilution causes it to dissociate from the enzyme |
|
|
Term
|
Definition
| type Z mutation in elastase inhibitor - lys substitutes for glu-53. |
|
|
Term
| What do elastase inhibitors do? |
|
Definition
| prevent elastase enzymes from digesting alveolar proteins in the lungs |
|
|
Term
|
Definition
| z-mutation in elastase inhibitor |
|
|
Term
| What do enzymatic cascades serve to do? |
|
Definition
| amplify a cellular signal |
|
|
Term
| What is an example of enzymatic cascade utilizing the consequential amplification? |
|
Definition
|
|
Term
| Aldoses and ketoses of appropriate lengths can cyclize forming what two rings? |
|
Definition
|
|
Term
| Aldehydes form what kind of linkages? |
|
Definition
|
|
Term
| Ketoses form what kind of linkages? |
|
Definition
|
|
Term
| The number 5 carbon in carbohydrate rings, this carbon is the what? |
|
Definition
|
|
Term
| Ketose sugars are capable of rearranging their structures into aldoses via what mechanism? |
|
Definition
|
|
Term
| When ketose and aldose forms of sugars are in equilibrium, which form predominates? |
|
Definition
|
|
Term
| What is another term for ketoses? |
|
Definition
|
|
Term
| Sugars with aldehyde groups (or potential aldehydes) are called what? |
|
Definition
|
|
Term
| Reducing sugars can reduce what (with blue solution) to what and is the basis for what test? |
|
Definition
| Cu2+ to Cu1+ (insoluble red precipitate) - Benedicts test |
|
|
Term
| What is Fehling's solution used for? |
|
Definition
| the benedict's test - testing for reducing sugars |
|
|
Term
| Manitol, sorbitol, and other things like this are examples of what? |
|
Definition
| sugar alcohols - aldoses that have been reduced to sweeten products that we consume |
|
|
Term
| What is the term for carbohydrates that are locked into their cyclic form (cannot open the ring preventing aldehyde formation)? |
|
Definition
|
|
Term
| What is the difference between hemiacetal and acetal linkages? |
|
Definition
| C-O-C-OH (hemiacetal) vs. C-O-C-O-CH3 (acetal) |
|
|
Term
| How is a nonreducing sugar produced? |
|
Definition
| by making an acetal group where otherwise a hemiacetal group would be present, locking the ring into ring form |
|
|
Term
| What two unique items are present in heparin polymers? |
|
Definition
|
|
Term
|
Definition
| prevents thrombin from converting fibrinogen into fibrin, so it is a anticoagulant |
|
|
Term
| Sucrose is formed by what? is it a reducing sugar? |
|
Definition
| a glycosidic linkage alpha(1-2) linkage between glucose and fructose - thus, it is NOT a reducing sugar |
|
|
Term
| Lactose is what kind of linkage? |
|
Definition
|
|
Term
| The most common polysaccharide in animal cells is what? |
|
Definition
|
|
Term
| Glycogen is a polymer of glucose, containing both _______ and ______ linkages at branch points |
|
Definition
| alpha (1-4) and alpha (1-6) |
|
|
Term
| Branching occurs about every ______ glucose molecules in glycogen |
|
Definition
|
|
Term
| The hemiacetal at the #1 carbon in the first monomer of the polymer of glycogen is significant because why? |
|
Definition
| it is the only reducing sugar in the whole polymer |
|
|
Term
| Starch is also called what? |
|
Definition
|
|
Term
| Amylose is a what kind of polysaccharide? |
|
Definition
|
|
Term
| The branched form of amylose is called what? |
|
Definition
|
|
Term
| Amylopectin has a lower degree of branching, occurring at a rate of 1 out of every _____ glucose residues. |
|
Definition
|
|
Term
| Fruits are gassed with what to prevent ripening? |
|
Definition
|
|
Term
| Once fruit has arrived at its destination, it is then gassed again with what to promote ripening? |
|
Definition
|
|
Term
| Methylcyclopropene is what with regard to fruit ripening? |
|
Definition
| a competitive inhibitor for the ethylene that ordinarily promotes ripening |
|
|
Term
| In aqueous solutions, starch molecules take what shape? |
|
Definition
|
|
Term
| Starch's helical structure in solution accommodates what into its color causing a color change to blue/black? |
|
Definition
|
|
Term
| What enzyme catalyzes starch in the food that we consume in the saliva? |
|
Definition
|
|
Term
| Amylase catalyzes the hydrolysis of what bonds? |
|
Definition
|
|
Term
| Starch -> ___________ -> maltose -> ____________? |
|
Definition
|
|
Term
| Partially __________ starches are more soluble than starch. |
|
Definition
|
|
Term
| Mixtures of what and what are used in baby foods and infant formulas? |
|
Definition
|
|
Term
| The large size of glycogen prevents what? |
|
Definition
| the glycogen molecules from diffusing out of the cells |
|
|
Term
| Storage of glycogen reduces _______ pressure? |
|
Definition
|
|
Term
| When glycogen becomes highly concentrated in the cell, it can __________ or ___________ into _________ __________. |
|
Definition
| precipitate or crystallize, glycogen granules |
|
|
Term
| Cellulose is the polyglucose polysaccharide that uses what kind of linkages? |
|
Definition
|
|
Term
| Cellulose has a much higher ________ strength than starches. |
|
Definition
|
|
Term
| Humans cannot digest cellulose because why? |
|
Definition
| We do not have an enzyme that is capable of breaking beta (1-4) linkages |
|
|
Term
| How are other animals able to digest cellulose? |
|
Definition
| Symbiotic bacteria present in the gut of these animals. these bacteria do synthesize enzymes that can hydrolyze beta (1-4) linkages |
|
|
Term
| What do glycotransylferases do? |
|
Definition
| synthesize polymeric carbohydrates |
|
|
Term
| In blood typing, what is the common oligosaccharide in what blood type polysaccharides? |
|
Definition
|
|
Term
| Type A blood has what that differs from O blood? |
|
Definition
| adds N-acetylgalactosamine |
|
|
Term
| Type B differs from type O how? |
|
Definition
|
|
Term
| The two enzymes' primary structure for A and B blood types differs by only how many amino acids? |
|
Definition
|
|
Term
| Some microorganisms utilize specific what to bind to host cells? |
|
Definition
| specific carbohydrate structures |
|
|
Term
| Influenza viruses recognizes what compound on cell surfaces of hosts? |
|
Definition
|
|
Term
| The fat content of foods is determined by what? |
|
Definition
| simple extraction (with hexane) |
|
|
Term
| How do you figure out fat content per serving? |
|
Definition
| samples are extracted in hexane for extended periods of time. the hexane is then separated from the food and then the hexane is evaporated off. the mass of residual materials is collectively called the fat content |
|
|
Term
| lipids can be broken down into two different categories called what? |
|
Definition
| saponifiable and non saponifiable |
|
|
Term
| Steroids and prostaglandins are what categorization of lipids? |
|
Definition
|
|
Term
| ________ _______ are the primary component of lipids. |
|
Definition
|
|
Term
| Almost all double bonds in naturally occuring fatty acids are in the ______ configuration. |
|
Definition
|
|
Term
| The IUPAC system assigns #1 to the ________ carbon of lipids |
|
Definition
|
|
Term
| For lipids, biochemists use the greek alphabet, and the #2 carbon becomes what? |
|
Definition
|
|
Term
| For lipids, the terminal carbon is always named the what? |
|
Definition
|
|
Term
| In lipids, double bonds are often identified by their distance from what? |
|
Definition
|
|
Term
| Why do you never have odd numbered carbon lipids? |
|
Definition
| b/c they are synthesized two carbons at a time |
|
|
Term
| Prostaglandins are synthesized from what acid? |
|
Definition
|
|
Term
| Prostaglandins also promote what? |
|
Definition
|
|
Term
| Aspirin and Ibuprofen inhibit what? |
|
Definition
| the first enzyme in the inflamm. pathway, prostaglandin H2 synthetase |
|
|
Term
| The fluidity (melting points) of lipids depends upon what? |
|
Definition
| chain length and degree of unsaturation |
|
|
Term
|
Definition
| an emulsion of oil and water |
|
|
Term
| What component of margarine influences its melting point? |
|
Definition
|
|
Term
| What is the main source of oil for margarin? |
|
Definition
|
|
Term
| A higher number of double bonds will do what to the texture of margarine? |
|
Definition
| make it softer. fewer double bonds makes it stiffer |
|
|
Term
| Cis-configured double bonds do what to the melting points of margarine? |
|
Definition
| they disrupt dipole interactions and the orderly stacking of saturated fatty acids, lowering the melting point |
|
|
Term
| Catalytic hydrogenation produces what? |
|
Definition
| sometimes when hydrogenating a double bond, the single bond will rotate into a trans configuration, producing trans-fats |
|
|
Term
| The degree of unsatruation is measured by what method? |
|
Definition
| titration of double bonds with molecular iodine |
|
|
Term
| The iodine number is the number of grams of iodine that reacts with what? |
|
Definition
|
|
Term
| The most common storage form of fats are what? |
|
Definition
|
|
Term
|
Definition
|
|
Term
| Three fatty acids are _________ to ________, one to each alcoholic group |
|
Definition
|
|
Term
| Most lipids found in membranes are what? |
|
Definition
|
|
Term
| Another class of saponifiable lipids are built around what rather than glycerol? |
|
Definition
|
|
Term
| Sphingomyelin contains a what kind of ester and a second fatty acid linked by what kind of bond? |
|
Definition
|
|
Term
| WHich bond is saponifiable in sphingomyelin? |
|
Definition
|
|
Term
| Cerebrosides are composed of what 3 things? |
|
Definition
| sphingosine, fatty acid, and a carbohydrate |
|
|
Term
| Cholesterol is a lipid with an entirely different what from other lipids? |
|
Definition
|
|
Term
|
Definition
|
|
Term
| Cholesterol is composed of what 4 things? |
|
Definition
| 4 fused hydrocarbon rings |
|
|
Term
| Cholesterol is synthesized by whom? |
|
Definition
| animals, not plants or prokaryotes |
|
|
Term
| Cholesterol is the starting material for the biosynthesis of what 3 things as examples? |
|
Definition
| hormones, vitamin D, and bile salts |
|
|
Term
| Bile salts are ________ agents that help solubilize dietary lipids in the aqueous environment if the GI |
|
Definition
|
|
Term
| Bile is synthesized where? |
|
Definition
|
|
Term
| Bile salts are stored where? |
|
Definition
|
|
Term
| Fresh bile is _______, but upon standing, it turns _______ and finally ________. |
|
Definition
|
|
Term
| The body excretes ________ to ________ grams of bile daily and is responsible for the color of what? |
|
Definition
|
|
Term
| Waxes (that are used to coat feathers) are what of long-chain fatty acids and fatty alcohols? |
|
Definition
|
|
Term
|
Definition
sheet-like structures only two molecules thick
consist of mainly lipids and proteins
form spontaneously into lipid bilayers
are non-covalent assemblies
are asymmetric
are fluid structures
are electrically polarized |
|
|
Term
| Ionized lipids such as phospholipids spontaneously form what? |
|
Definition
|
|
Term
| Sonication of phospholipid suspensions yield what? |
|
Definition
|
|
Term
| How are artificial lipid vessicles formed? |
|
Definition
| sonication of phospholipids |
|
|
Term
| How can liposomes be used to study cell behavior in different environments? |
|
Definition
| They can form artificial membranes through gel filtration that can be used to study different behavior on cells in solution with different solution contents |
|
|
Term
| Artificial BLM stands for what? |
|
Definition
|
|
Term
| ABLM's can be formed how? |
|
Definition
| can be formed across small millimeter-sized holes by "painting" the lipid mixture over the holes. this causes artificial BLM's form spontaneously, and then when this is complete, the bilayer looks black due to destructive interference of refracted light |
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Term
| In making ABLM's, the bilayer looks black due to what? |
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Definition
| destructive interference of refracted light |
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Term
| The hydrophobic nature of the middle of membranes makes them excellent barriers to what? |
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Definition
| ionic and polar molecules |
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Term
| membrane proteins are classified by how strongly they are held by what? |
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Definition
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Term
| Peripheral proteins are held by what? |
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Definition
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Term
| The fluid mosaic model of membranes explains what? |
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Definition
| why individual lipid molecules are free to diffuse latterally across the membrane, but they cannot easily flip over |
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Term
| What method can be used to visualize lipid molecules diffusing laterally across membranes? |
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Definition
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Term
| Bacteria regulate the fluidity of their membranes by varying the degree of what? |
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Definition
| the degree of unsaturation and the length of their fatty acids |
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Term
| Membrane fluidity is often characterized by their phase transition temperature, or what? |
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Definition
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Term
| Prostaglandin H2 synthetase is an integral protein and is held in its membrane by a set of _____ _______ coated with _________ side chains |
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Definition
| alpha helices, hydrophobic |
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Term
| In Prostaglandin H2, a hydrophobic channel shuttles what into position for conversion? |
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Definition
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Term
| Aspirin blocks what aspect of prostaglandin H2? |
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Definition
| the channel that shuttles in arachadonic acid |
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