Flashcards
Enzymes
Flashcards do conjunto (82)
- 1what are enzymes?proteins (exceptions are ribozymes - RNA enzymes)
highly specific for the reactions they catalyze for - 2what are biological catalysts?accelerate the rate of a chemical reaction by lowering the activation E
- 3true or false: the rate of a reaction is often decreased dramatically by the presence of an enzymefalse
- 4what the formula to calculate the Rate VRate V = product amount/time
- 5true or false: enzymes change the delta Gfalse
- 6true or false: enzymes do not change the equilibrium {} of substrates (reactants) nor productstrue
- 7true or false: enzymes can catalyze overall endergonic reactionsfalse
- 8true or false: enzymes can catalyze overall exergonic reactionstrue
- 9true or false: heat released by the enzyme catalyzed will help accelerate enzyme activityfalse
- 10what do active sites provide to the environment?favours the transition state formation
- 11what are active sites?pocket with key amino acid side chains (functional groups) located within the enzyme to which the substrate binds;
stress the substrate & stabilize the transition state - 12what is an induced fit?conformational change of the enzyme when bound with substrate that favours transition state formation;
enzyme changes shape so its active site embraces the substrates - 13true or false: enzymes are modified by the reaction and are not recycledfalse
- 14what holds the substrates in the active sites?weak interactions {hydrogen bonds & ionic bonds}
- 15what is enzymologist?the study of velocity of enzyme catalyzed reactions & of factors that affect velocity
[substrate], [enzyme], T, pH - 16what is the velocity?rate of product formation (or rate of substrate disappearing)
- 17what is vmax?the maximal velocity reached at a given enzyme concentration
- 18when is vmax reached?when [S] is in excess & all enzyme molecules are bound with a substrate
- 19what is Km?it is equal to substrate [] that will give a Velocity=Vmax/2
- 20Km in some cases can be considered the (blank) of the enzyme for the substrateaffinity
- 21for Michaelis-Menton enzymes: initial rate of reaction for a given enzyme [] (increases or decreases) linearly with increased substrate []s in low rangeincreases
- 22as more substrate molecules are present, the number of collisions with the enzymes (blank)increases
- 23why, in high range, does the initial rate level off at Vmax?because the enzyme molecules become limiting
- 24in what situation does increased enzyme []s also increase the initial rates of reaction?when the substrate(s) are in excess
- 25~Major groups of enzymes~ what enzymes are classified as?oxidoreductases
- 26~Major groups of enzymes~ what type of reactions do oxidoreductases carry out?redox reactions
- 27~Major groups of enzymes~ what is a basic explanation of redox reactions?a transfer of electrons
- 28~Major groups of enzymes~ explain and provide an example of transferasestransfer functional groups from one molecule to another
e.g. protein kinases - 29~Major groups of enzymes~ explain and provide an example of hydrolasesuse water to cleave chemical bonds, usually dividing a large molecule into two smaller molecules
e.g. proteases like trypsin - 30~Major groups of enzymes~ explain and provide an example of isomerasesconvert a molecule from one isomer to another
e.g. glycolysis - 31~Major groups of enzymes~ explain and provide an example of ligasescreate covalent bonds
e.g. ligase during DNA replication; Rubisco & Pep carboxylase in photosynthesis - 32~Major groups of enzymes~ explain and provide an example of lyasescleave C-C, C-O, C-N bonds by other means than hydrolysis or oxidation
e.g. glycolysis - 33~Enzyme Cofactors~ which enzymes require cofactors?apoenzymes
- 34~Enzyme Cofactors~ true or false: can cofactors be organic or inorganic?true
- 35~Enzyme Cofactors~ what is another name for organic cofactors?coenzymes
- 36~Enzyme Cofactors~ list examples of coenzymes (aka organic cofactors)NADH,
NADPH,
FADH2,
vitamin B,
chlorophyll - 37~Enzyme Cofactors~ list examples of inorganic cofactorsFe,
Cu,
Zn,
Mn - 38~Enzyme Cofactors~ true or false: can apoenzymes be active without their cofactors?false
- 39~Enzyme Cofactors~ what is a cofactor?a non-protein chemical compound or metallic ion that is required for a protein's biological activity to happen
"helper molecules" - 40~Changing Environmental Conditions~ what happens to enzyme activity when it is below optimal temperature?substrate molecules do not have enough kinetic E & the # of collisions with enzyme are low
- 41~Changing Environmental Conditions~ what happens to enzyme activity when it is above optimal temperature?denaturation --> secondary, tertiary & quaternary structures are disrupted
- 42~Changing Environmental Conditions~ what happens to enzyme activity when it is below or above optimal pH?changes in charges of R groups affect their ionic interactions & therefore the 3D structure of enzymes (proteins in general)
- 43~Changing Environmental Conditions~ what happens when there's an addition of H+ or of OH- in the cell?charge of acidic or of basic R is affected --> ionic interaction is disrupted
- 44~Effect of Heavy Metals, Salt & Reducing Agents~ heavy metals & salt disrupt which interactions?ionic interactions
+/-
disulfide bonds - 45~Effect of Heavy Metals, Salt & Reducing Agents~ reducing & oxidizing agents disrupt which interaction?S-S bonds
- 46~Effect of Heavy Metals, Salt & Reducing Agents~ what happens to the protein-enzyme when there is a change from a polar to nonpolar solvent?the protein-enzyme flips inside out
- 47~Effect of Heavy Metals, Salt & Reducing Agents~ denatured (unfolded) enzymes/proteins maintain which structure?primary
- 48~Effect of Heavy Metals, Salt & Reducing Agents~ what are two consequences of denaturing your protein/enzyme?looses activity
sometimes aggregates (from clumps --> think of cooked egg white) - 49~Enzymes of Metabolic Pathways~ A->B->C->D E1 E2 E3 enzymes are found in the same (blank) compartment?cellular
- 50~Enzymes of Metabolic Pathways~ A->B->C->D E1 E2 E3 enzymes function together to form a (blank)common product
- 51~Enzymes of Metabolic Pathways~ A->B->C->D E1 E2 E3 product of one serves as a (blank) for nextsubstrate
- 52~Enzymes of Metabolic Pathways~ A->B->C->D E1 E2 E3 in what situation would the overall pathway be ON & delta G be negative?if the initial substrate is in excess & final product is immediately removed/utilized
- 53in which compartment are situated cellular respiration enzymes?mitochondria
- 54in which compartment are situated lipid synthesis enzymes?SER
- 55~Enzyme Regulation~ how are enzymes regulated?1. amount of enzyme produced by gene expression --> slow & coarse
2. small modifying molecules --> rapid & fine - 56~Enzyme Regulation~ describe activators and list some examplesincrease the activity of enzymes
e.g. Pi or ADP - 57~Enzyme Regulation~ describe inhibitors and list some examplesend-products of metabolic pathways decrease the activity of enzymes
e.g. ATP - 58~Enzyme Regulation~ describe what competitive inhibition isthe competitive inhibitor, which mimics the substrate, binds to the active site
- 59~Enzyme Regulation~ describe what noncompetitive inhibition isthe noncompetitive inhibitor binds to the allosteric site
- 60~Enzyme Regulation~ true or false: inhibition of enzyme activity is nonreversiblefalse
- 61~Enzyme Regulation~ what is another word for noncompetitive inhibition?allosteric regulation
- 62~Comparison of Competitive & Non Competitive Inhibition~ inhibitor binds to ...competitive: active site
non competitive: allosteric site - 63~Comparison of Competitive & Non Competitive Inhibition~ inhibitor resembles ...competitive: substrate
non competitive: different from substrate - 64~Comparison of Competitive & Non Competitive Inhibition~ Vmax ...competitive: same as before
non competitive: lower - 65~Comparison of Competitive & Non Competitive Inhibition~ Km ...competitive: is greater
non competitive - 66~Comparison of Competitive & Non Competitive Inhibition~ which of the two inhibitors can be overcome? and how?the competitive one, by increasing [substrate]
- 67~Enzyme Regulation~ explain the pathway of feedback inhibitionwhen end product accumulates
1. binds to allosteric site of first enzyme in pathway
2. changes active site
3. initial substrate can no longer bind
4. velocity is decreased
5. pathway activity is reduced or OFF - 68~Enzyme Regulation~ is feedback inhibition a type of competitive or non competitive inhibition?non competitive
- 69~Enzyme Regulation~ how would feedback inhibition be positive?if the end product activated enzyme 1 to produce more end product
- 70~Enzyme Regulation~ are allosteric enzymes similar or different to simple Michaelis-Mention (MM) enzymes?different
- 71~Enzyme Regulation~ what is a basic definition of allosteric enzymes?multi-subunit enzymes with multiple sites
- 72~Enzyme Regulation~ what structure do allosteric enzymes have?quaternary structure
- 73~Enzyme Regulation~ true or false: allosteric enzymes exist in active & inactive forms?true
- 74~Enzyme Regulation~ substrate binding of allosteric enzymes are (blank)cooperative
- 75~Enzyme Regulation~ how are allosteric enzymes stabilized?by the binding of activators or inhibitors to allosteric site(s)
- 76~Enzyme Regulation~ ADP is an allosteric activator or inhibitor?activator
- 77~Enzyme Regulation~ ATP is an allosteric activator or inhibitor?inhibitor
- 78~Enzyme Regulation~ what is an example of an allostericphosphofructokinase (glycolysis)
- 79~Enzyme Regulation~ how many substrates must bind active sites of one subunit of an allosteric enzyme to lock all subunit in active conformation?only one
- 80~Enzyme Regulation~ which types of inhibitions are reversible?competitive,
non competitive,
allosteric - 81~Enzyme Regulation~ when does irreversible inhibition occur?when the inhibitor destroys the enzyme by covalently binding to it
- 82~Enzyme Regulation~ what are some examples of irreversible inhibition?nerve gase inhibits acetylcholine esterase --> prolonged muscle contraction
penicillin inhibits formation of bacterial cell wall
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- Biology 2 (Unit 1) FlashCards sobre Enzymes, criado por Bianca Adams em 30-01-2017.
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- Bianca Adams
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