Help
Options
Didn't know it?
click below
click below
Knew it?
click below
click below
Don't Know
Remaining cards (0)
Know
retry
shuffle
restart
0:00
Embed Code - If you would like this activity on your web page, copy the script below and paste it into your web page.
Normal Size Small Size show me how
Normal Size Small Size show me how
Biochem Old Exam
| Question | Answer |
|---|---|
| Enzymes that bind reaction transition state analogs with greater affinity than substrates or products | Are inhibited by the transition state analogs |
| Metalloenzymes | All of the above (Bind substrates to orient them properly for rxn, mediate redox rxns through reversible changes in metal ion's oxidation state, electrostatically stabilize or shield negative charges) |
| Metal catalysis is generally more efficient than base catalysis because | All of the above (Act like proton to neutralize negative charge, bind water, accelerate reaction rate) |
| Biological nucleophiles are ______ and take part in __________ catalysis. | Negatively charged or contain unshared pairs that can form covalent bonds with electron deficient centers; covalent |
| Which of the below characteristics are NOT found in enzyme catalyzed reactions? | Higher delta G of transition state |
| Which of the below statements are true for enzyme catalyzed reactions? | Alkl of the above (enzymes exhibit electronic comp for substrates, some enzymes exhibit induced fit, specific binding is necessary but not sufficient for catalysis, enzymes exhibit comp for substrates) |
| NAD | Haloenzyme |
| Cofactor permanently associated with enzyme | Prosthetic group |
| Inactive enzyme due to loss of cofactor | Cofactors |
| Small organic molecule | Coenzymes |
| Can be metal ion or small organic molecules | Apoenzyme |
| Catalytically active enzyme-cofactor complex | Cosubstrate |
| Of the below ways that enzymes utilize promimity and orientation effects to facilitate rxns, which one is thought to have the greatest effect on the reaction rate? | All of the above (enzymes bring substrate in contact with catalytic groups, enzymes place substrates in proper orientation for rxn, charged groups may stabilize TS of rxn, enzymes "freeze out" translational and rotational motions) |
| The 2A --> B reaction is | Bimolecular (second order) |
| The rate (velocity) of the reaction 2A --> B is determined by | k[A]2 |
| The zeroth order reaction's rate is dependent on the | Rate constant |
| The rate (velocity) of the reaction A B is determined by | k[A] |
| The type of enzyme inhibition in which Vmax is unaffected is | Competitive inhibition |
| In uncompetitive inhibition, the inhibitor binds only to the | ES complex |
| A common type of covalent modification of regulatory enzymes involves ______ to serine | Phosphorylation |
| In _______ the inhibitor binds to a site involved in both substrate binding and catalysis | Mixed inhibition |
| What is the velocity of a first order rxn when the reactant concentration is 6 x 10^-2 M and the rate constant is 8 x 10^3/sec? | 4.8 x 10^2 M/sec |
| Second-order reactions | Occur when two reactants collide |
| For a reaction A + B --> C, if the concentration of B is much larger than [A] so that [B] remains constant during the reaction while [A] is varied, the kinetics will be | Pseudo first order |
| Km is | A measure of the affinity of substrate binding |
| When [S] = Km, vo = _____ vmax | 0.5 |
| A Lineweaver-Burk plot is also called | A double reciprocal plot |
| If the half-life of a given reaction is constant (not dependent upon the initial concentrations), the reaction must be | First order |
| Pseudo-first order rxn kinetics would be observed for the reaction A + B --> C | None of the above |
| E + S <--> ES --> P + E The overall transformation | All of the above (Is composed of the 2 elementary rxns, can be zeroth order in [S] if [S]>>[E], may be described by the Michaelis-Menten equation) |
| For the reaction, the steady state assumption assumes that | [ES] is constant |
| A compound that reversibly reduces the concentration of enzyme available for substrate binding is called | A competitive inhibitor |
| Compounds that function as "mixed inhibitors" | All of the above (interfere with substrate binding to the enzyme, bind to the enzyme reversibly, can bind to the enzyme/substrate complex) |
| Enzyme activity in cells is controlled by processes including | All of the above (modulation of expression levels, feedback inhibition, binding to allosteric effectors, temporary covalent modifications) |
| Allosteric activators bind to enzymes | Covalently |
| Protein kinases are involved in | Phosphorylation of a wide variety of proteins |
| What is the definition of allosteric effector? | Work by altering the structure of an enzyme to either increase or decrease enzyme reactivity |
| Which of the below enzymatic modifications do hormones utilize to alter cellular enzyme activity? | Allosteric modification |
| A reaction with a _______ delta H and a _______ delta S, will always be spontaneous | Negative Positive |
| Phosphoric acid is a polyprotic (pk1=2.12, pk2 = 7.21, pk3 = 12.67). Which ionic form predominates at pH 7? | HPO4 2- |
Created by:
14madmil