CHEE 416 - Biochemical Engineering Exam 2 - ?'s

Often, the kinetic values of an enzyme are plotted using the Lineweaver-Burk equation: 1/v0 = Km/Vmax *1/[S] + 1/Vmax. Enter 'Yes' or 'No' to indicate if the equation and graphical terms match in each statement. 1) y-intercept and -1/Km 2) x-intercept and 1/Vmax 3) slope and Km/Vmax

1) No 2) No 3) Yes

Enzymes differ from other catalysts in that only enzymes: A) are not consumed in the reaction. B) display specificity toward a single reactant. C) fail to influence the equilibrium point of the reaction. D) form an activated complex with the reactants. E) lower the activation energy of the reaction catalyzed.

B) display specificity toward a single reactant.

Which of the following is true of the binding energy derived from enzyme-substrate interactions? A: It cannot provide enough energy to explain the large rate acceleration brought about by enzymes B: It is sometimes used to hold two substrates in the optimal orientation for reaction C: It is the result of covalent bonds formed between enzyme and substrate D: Most of it is derived from covalent bonds between enzyme and substrate E: Most of it is used up simply binding the substrate to the enzyme

B: It is sometimes used to hold two substrates in the optimal orientation for reaction

Which one of the following is considered best sterilizer for liquid culture medium? A: Ethylene oxide B: Membrane filters C: Surface active agents D: Alcohols

B: Membrane filters

In an enzyme controlled reaction, an increase in temperature will usually: A: Speed up a reaction (without limits) B: Speed up a reaction (within limits) C: Slow down a reaction (without limits) D: Slow down a reaction (within limits)

B: Speed up a reaction (within limits)

Enzymes are catalysts. They increase the rate of chemical reactions by: A: Raising the activation energy B: Stabilizing the transition state C: Temporarily increasing the temperature D: Covalently binding the substrate

B: Stabilizing the transition state

The concept of "induced fit" refers to the fact that: A: When a substrate binds to an enzyme, the enzyme induces a loss of water (desolvation) from the substrate B: Substrate binding may induce a conformational change in the enzyme, which then brings catalytic groups into proper orientation C: Enzyme-substrate binding induces an increase in the reaction entropy, thereby catalyzing the reaction D: Enzyme specificity is induced by enzyme-substrate binding E: Enzyme-substrate binding induces movement along the reaction coordinate to the transition state

B: Substrate binding may induce a conformational change in the enzyme, which then brings catalytic groups into proper orientation

When a substrate binds to an enzyme, which of the following is true? A: All enzymes work best at neutral pH B: There is an optimum pH for each specific enzyme C: Enzyme works well at any pH higher than optimum D: Enzymes work well at any pH lower that optimum E: At a low pH, an enzyme needs more kinetic energy to function

B: There is an optimum pH for each specific enzyme

Which statement is true? A: Enzymes generally have a functional temperature range that is identical to its optimal temperature range B: When an enzyme is denatured, its spatial structure is permanently changed C: Most enzymes are more sensitive to low temperature than high temperature D: All of the above

B: When an enzyme is denatured, its spatial structure is permanently changed

Which of the following statements in true of enzyme catalysts? A: To be effective, they must be present at the same concentration as their substrate B: They can increase the equilibrium constant for a given reaction by a thousand-fold or more C: They lower the activation energy for conversion of substrate to product D: Their catalytic activity is independent of pH E: They are generally equally active on D and L isomers of a given substrate

C: They lower the activation energy for conversion of substrate to product

Enzymes are classified by the: A: Size of the enzyme B: Size of the substrate C: Type of reaction they catalyze D: Rate of reaction

C: Type of reaction they catalyze

Which one of the following statements is incorrect? A: Chemical agents have oxidizing or alkylating abilities B: Many cellular materials absorb ultraviolet light, leading to DNA damage and consequently to cell death C: Ultraviolet rays (~265 nm) have a higher ability to penetrate than X-rays D: None of the above

C: Ultraviolet rays (~265 nm) have a higher ability to penetrate than X-rays

Which one of the following is false? A: After a reaction, the enzyme involved becomes available to catalyze the reaction again B: For substrate to product conversion, a catalyst shifts the reaction to the right C: Lowering the temperature of a reaction will lower the reaction rate D: Substrate binds to an ES active site

D: Substrate binds to an ES active site

Which of the following statements is true of enzyme catalysts? A: Their catalytic activity is independent of pH B: They are generally equally active on D and L isomers of a given substrate C: They can increase the equilibrium constant for a given reaction by a thousand fold or more D: They can increase the reaction rate for a given reaction by a thousand fold or more E: To be effective, they must be present at the same concentration as their substrate

D: They can increase the reaction rate for a given reaction by a thousand fold or more

Which one of the following statements is incorrect? A: The change in cell concentration in batch fermenter is equal to the cell growth rate B: rate of an autocatalytic reaction increases as cell multiple C: Continuous fermenter is considered as an open system D: Turbidostat is easier to operate than chemostat

D: Turbidostat is easier to operate than chemostat

Which of the following statements about a plot of V0 vs. [S] for an enzyme that follows Michaelic-Menten kinetics is false? A: Km is the [S] at which V0 = 0.5 Vmax B: The shape of the curve is a hyperbola C: The y-axis is a rate term with units of nano-m/min D: As [S] increases, the initial velocity of reaction, V0, also increases E: At very high [S], the velocity becomes a horizontal line that intersects the y-axis at Km

E: At very high [S], the velocity becomes a horizontal line that intersects the y-axis at Km

The transition state of a catalyzed reaction is lower in energy than that of the uncatalyzed reactions because: A: Of enthalpic interactions between the enzyme and the transition state B: Of favorable interactions with the substrate C: Of a smaller delta S between the [ES] and [EX] complex D: Enzymes only work at low temperatures E: Both A and C are correct

E: Both A and C are correct

Enzymes are potent because they: A: Are consumed in the reactions they catalyze B: Are very specific and can prevent the conversion of products back to substrates C: Drive reactions to completion while other catalysts drive reactions to equilibrium D: Increase the equilibrium constants for the reactions they catalyze E: Lower the activation energy for the reactions they catalyze

E: Lower the activation energy for the reactions they catalyze

Enzymes are potent catalysts. They: A: Drive reactions to completion while other catalysts drive reactions to equilibrium B: Are consumed in the reactions they catalyze C: Are very specific and can prevent the conversion of products back to substrates D: Increase the equilibrium constants for the reactions they catalyze E: Lower the activation energy for the reactions they catalyze

E: Lower the activation energy for the reactions they catalyze

Removal of pathogenic microorganisms except bacteria spores is known as A: Sterilization B: Disinfection C: Cleaning D: Decontamination

B: Disinfection

Alkylation of proteins and amino acids is not the attribute of the following: A: Formaldehyde B: Halogens C: Ethylene oxide D: Alcohol

B: Halogens

The active site of an enzyme remains: A: At the center of globular proteins B: Rigid and does not change shape C: Complementary to the rest of the molecule D: None of the above

D: None of the above

Microbial kill in the ozone sterilizer is achieved through a process called: A: Condensation B: Alkylation C: Cavitation D: Oxidation

D: Oxidation

Choose the incorrect statement about active site of an enzyme? A: The active site is a 3-D cleft B: Active site takes up a large part of the total volume of an enzyme C: Substrate is bound to enzymes by multiple weak attractions D: The specificity of binding depends on the precisely defined arrangements of atoms in an active site

B: Active site takes up a large part of the total volume of an enzyme

Which form of sterilization is widely employed on liquids as well as temperature resistance solid objects? A: Moist heat B: Dry heat C: Ozone treatment D: UV treatment

A: Moist heat

Which of the following is a wet sterilization system for unwrapped items? A: Peracetic acid B: Hydrogen peroxide gas plasma C: Ethylene oxide D: Ozone sterilization

A: Peracetic acid

While bound to active site, substrate is converted into? A: Product of reaction B: Another substrate of high energy C: Stable substrate D: All of the above

A: Product of reaction

Destroys all forms of microorganisms is known as A: Sterilization B: Disinfection C: Cleaning D: Decontamination

A: Sterilization

The relationship between an enzyme and a reactant molecule can best be described as: A: A temporary association B: An association stabilized by a covalent bond C: One in which the enzyme is changed permanently D: A permanent mutual alteration of structure E: Non-complementary binding

A: A temporary association

The curve of CX vs 1/rx, the shaded area under the curve is equal to: A: Batch growth time B: Fermentation time C: Time when MO are just inoculated in fermenter D: All of the above

A: Batch growth time

The benefit of measuring the initial rate of a reaction, V0, is that at the beginning of a reaction: A: Changes in [S] are negligible, so [S] can be treated as a constant B: [ES] can be measured accurately C: V0 = Vmax D: Changes in Km are negligible, so Km can be treated as a constant E: Varying [S] has no effect on V0

A: Changes in [S] are negligible, so [S] can be treated as a constant

Which sterilization techniques are applicable for plastic syringes and glass wares? A: Gamma rays and autoclaving, respectively B: Halogen and autoclaving, respectively C: Ethylene oxide and gamma rays, respectively D: Alcohol and ethylene oxide, respectively

A: Gamma rays and autoclaving, respectively

Activation energy is the energy required to? A: Get a reaction started B: Synthesize new compounds C: Break drown incoming molecule D: All of the above

A: Get a reaction started

Sterilization via oxidation is an attribute of which technique? A: Halogens B: UV C: Autoclaving D: Gamma rays

A: Halogens

Sterilization via oxidation is an attribute if which technique? A: Hot dry air B: Surface active agents C: Autoclaving D: Alcohol

A: Hot dry air

Enzyme action can be influenced by the presence of inhibitors. Which of the following statements correctly matches the type of inhibitor with its effect on an enzyme. A: Irreversible and renders the enzyme permanently inactive B: Competitive and inhibitor binds only to ES complex, only important when [S] high, Vmax lower, Km lower C: Noncompetitive and can be overcome with high [S]; Vmax unchanged, Km higher D: Noncompetitive and cannot be overcome with high [S]; Vmax lower, but Km unchanged

A: Irreversible and renders the enzyme permanently inactive

The transition state of a catalyzed reaction is: A: Lower in energy than that of an uncatalyzed reaction B: Lower in energy that the reaction substrate C: Bound very weakly to the catalyst D: A highly populated intermediate on the reaction pathway

A: Lower in energy than that of an uncatalyzed reaction

The active site of an enzyme differs from an antibody-antigen binding site in that the enzyme active site: A: Contains modified amino acids B: Catalyzes a chemical reaction C: Is complementary to a specific ligand D: Contains amino acids without side chains E: None of the above are correct

B: Catalyzes a chemical reaction

To increase the amount of end product in an enzyme facilitated reaction, you could: A: Boil the enzyme B: Add inhibitor C: Add more substrate D: Add ice

C: Add more substrate

***Which one of the following may no be the best sterilization techniques for metal objects, if used repeatedly? A: Ethylene oxide B: UV C: Autoclaving D: Gamma rays

C: Autoclaving

Moist heat is effective in sterilization because: A: Intrinsic heat resistance of bacterial cells is greatly increased in a completely dry state B: The heat conduction in dry air is less raid that in steam C: Both A and B D: None of the above

C: Both A and B

Removal of visible soil is known as A: Sterilization B: Disinfection C: Cleaning D: Decontamination

C: Cleaning

Anyone of the following processes except one are involved at the active site of an enzyme to accelerate the rate of reaction? A: Catalysis by bond strain B: Catalysis by bond proximity and orientation C: Covalent catalysis

C: Covalent catalysis

The role of an enzyme in an enzyme-catalyzed reaction is to: A: Ensure that the product is more stable than the substrate B: Make the free-energy change for the reaction more favorable C: Increase the rate at which substrate is converted into product D: Ensure that all substrate is converted into product E: Do none of the above

C: Increase the rate at which substrate is converted into product

Which of the following does not influence enzyme activity? A: pH B: Temperature C: Product degradation D: Effectors E: Substrate concentration

C: Product degradation

Which one of the following is related with disrupting the lipid bilayers of microorganisms by concentrating on the membranes of microorganism: A: Ethykene oxide B: Halogens C: Surface active agents D: Alcohols

C: Surface active agents

You are taking a tour of a municipal water treatment plant. Your guide discusses that water is sterilized before it is pumped as drinking water. What type of sterilization treatment should you expect to see on the tour? A: Iodine treatment B: Autoclaving C: Ethylene oxide percolation D: Ozone treatment

D: Ozone treatment

Which stage among the following exert greatest resistance for oxygen transfer from air bubbles to the surface of microbial cell: A: 1 B: 2 C: 3 D: 4

D: 4

An enzyme is A: A protein catalyst B: Under the direct control of DNA C: A substrate that lowers the activation energy D: All of the above

D: All of the above

Autoclaving is: A: Pressurizing a vessel at high temperatures B: Commonly operated at a steam pressure at about 30 psia C: sterilization technique operated at 121 C D: All of the above

D: All of the above

In a tubular flow fermenter: A: MO enter one end of cylindrical tube B: MO grow while they pass through the tube C: Flowing stream vary in longitudinal and radial direction D: All of the above

D: All of the above

To be functional, an enzyme must: A: Have a specific 3-D shape B: Attach to a substrate, forming an E-S complex C: Have a specific binding or attachment site D: All of the above

D: All of the above

Which one of the following statement is/are correct about fed-batch fermentation? A: Substrate and nutrients are added in small increments B: Low substrate concentration is maintained C: Volume increases with time in the reactor and reaches a maximum value D: All of the above

D: All of the above

Removal of pathogenic microorganisms is known as A: Sterilization B: Disinfection C: Cleaning D: Decontamination

D: Decontamination

In an enzymatic mechanism, substrate bind to enzyme active site to produce what? A: Reactant B: Products C: Enzymes D: ES Complex

D: ES Complex

The turnover number of an enzyme is the rate at which product is formed. E+S ES - k3 E+P turnover number = k3 = Vmax/[Et]. This is the maximum rate of product formation if all of the enzyme substrate binding sites are filled. What can the turnover number tell us about an enzyme? A: Number of binding sites B: Reaction mechanism C: Substrate concentration D: Enzyme efficiency

D: Enzyme efficiency

Which of the following statements is not true? A: Enzymes are proteins that bind to specific substrates and increase the velocity of reactions involving those substrates B: Enzymes function by overcoming the activation energy barrier of a reaction C: Enzymes make thermodynamically favorable reactions to proceed; they cannot make unfavorable reactions to occur D: Enzymes only function when they are in contact with the cells

D: Enzymes only function when they are in contact with the cells

Which of the statements regarding enzymes is false? A: Enzymes are specific B: Enzymes may be used many times for a specific reaction C: Enzymes are proteins that function as catalysts D: Enzymes provide activation energy for reactions

D: Enzymes provide activation energy for reactions

Plug flow fermenter does not have the following attribute: A: MO enter one end of cylindrical tube B: MO grow while they pass through the tube C: Flowing stream vary in longitudinal and radial direction D: Flowing stream vary in radial direction

D: Flowing stream vary in radial direction

Which of the following statements is false? A: A reaction may not occur at a detectable rate even though it has a favorable equilibrium B: At the end of an enzyme-catalyzed reaction, the functional enzyme becomes available to catalyze the reaction again C: Substrate binds to an enzyme's active site D: For S -> P, a catalyst shifts the reaction equilibrium to the right E: Lowering the temperature of a reaction will lower the reaction rate

D: For S -> P, a catalyst shifts the reaction equilibrium to the right

The role of an enzyme in an enzyme-catalyzed reactions is to: A: Bind a transition state intermediate. such that it cannot be converted back to substrate B: Ensure that all of the substrate is converted to product C: Ensure that the product is more stable than the substrate D: Increase the rate at which substrate is converted into product E: Make the free-energy change for the reaction more favorable

D: Increase the rate at which substrate is converted into product

Choose the correct statement. A: Oxygen is the most important gaseous substrate for anaerobic fermentation B: Oxygen is not a limiting factor for aerobic fermentation C: Oxygen is highly soluble in water D: Loop fermenter is a tank or column with a liquid circulation loop

D: Loop fermenter is a tank or column with a liquid circulation loop