Flashcards
MCAT enzymes
Cards in this deck (32)
- 1what are enzymes?biological catalysts that are unchanged by the reaction they catalyze and are reusable; lower the activation energy of reactions; do not alter the free energy or enthalpy nor the final equilibrium position, but change the rate at which equilibrium is reached
- 2oxidoreductasescatalyze oxidation-reduction reactions that involve the transfer of electrons
- 3transferasesmove a functional group from one molecule to another
- 4hydrolasescatalyze cleavage with the addition of water
- 5lyasescatalyze cleavage without the addition of water and without the transfer of electrons; the reverse reaction is often more important biologically
- 6isomerasescatalyze the interconversion of isomers, including both constitutional isomers and stereoisomers
- 7ligasesresponsible for joining two large biomolecules, often of the same type
- 8active sitesite of catalysis; where enzyme binds to the substrate
- 9lock and key theorythe enzyme and substrate are completely complementary
- 10induced-fit modelthe enzyme and substrate undergo conformational changes to interact fully
- 11coenzymes/cofactorscoenzyme: an organic molecule that helps an enzyme carry out its function
cofactor: an inorganic molecule or ion that helps an enzyme carry out its function - 12holoenzymes vs apoenzymesapoenzymes: enzymes without their cofactors
holoenzymes: enzymes with their cofactors - 13B vitaminsB1: thiamine
B2: riboflavin
B3: niacin
B5: pantothenic acid
B6: pyridoxal phosphate
B7: biotin
B9: folic acid
B12: cyanocobalamin - 14saturation kineticsas substrate concentration increases, the reaction rate does as well until a maximum value is reached
- 15Michaelis-Menten ratesE + S -> or <- ES -> E + P
arrows: K1/K-1 and Kcat - 16Michaelis-Menten equationv = vmax(S) / km + (S)
***when the reaction rate is equal to half of vmax, km = (s) - 17Turnover number (kcat)vmax = (E)(kcat)
- 18Michaelis-Menten plotrepresents the relationship between substrate concentration and reaction rate; hyperbola
- 19Lineweaver-Burk plotrepresents the relationship between 1/substrate concentration and 1/reaction rate; straight line; x-intercept is -1/km and y-intercept is 1/vmax
- 20What does Km represent?the enzyme's affinity for its substrate; the substrate concentration in which the enzyme is functioning at half its maximum velocity; as Km increases, the affinity decreases
- 21cooperativitythe interactions between subunits in a multisubunit enzyme or protein; the binding of a substrate to one unit can either change the other units from a tense state to a relaxed state (encouraging binding) or change the units from a relaxed state to a tense state (encouraging unbinding); display a sigmoidal curve
- 22factors that can affect enzyme activitytemperature & pH (in vivo); salinity (in vitro)
- 23zymogensinactive enzymes; are activated by cleavage
- 24phosphorylation/glycosylationcovalent modification with phosphate and carbs which can alter the activity or selectivity of enzymes
- 25irreversible inhibitionalters the enzyme in such a way that the active site is unavailable for a prolonged duration or permanently; new enzyme must be synthesized for the reaction to occur
- 26competitive inhibitionthe inhibitor binds to the active site; can be overcome by adding more substrate; Vmax is unchanged; Km increases
- 27noncompetitive inhibitionthe inhibitor binds to an allosteric site; binds with equal affinity to the enzyme and enzyme-substrate complex; Vmax is decreased; km is unchanged
- 28mixed inhibitionthe inhibitor binds to an allosteric site; binds with unequal affinity to the enzyme and enzyme-substrate complex; Vmax is decreased; Km varies
- 29uncompetitive inhibitionthe inhibitor binds to an allosteric site; binds only to the enzyme-substrate complex; Km and Vmax both decrease
- 30feedback inhibitiona regulatory mechanism whereby the catalytic activity of an enzyme is inhibited by the presence of high levels of a product later in the same pathway
- 31reversible inhibitionthe ability to replace the inhibitor with a compound of greater affinity or to remove it using mild laboratory treatment
- 32allosteric activators vs inhibitorsactivator: makes the active site more available for binding
inhibitor: makes the active site less available for binding
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- Flashcards on MCAT enzymes, created by Saige Boris on 17/08/2020.
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- Saige Boris
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