Quiz 4 Questions

Which of the following is true of a reaction that adds an amino acid to the end of a growing polypeptide chain (condensation reaction)? A) Condensation reactions are anabolic B) Condensation reactions are exergonic and therefore spontaneous C) Condensation reactions result in increased entropy D) Products have the same free energy as the reactants E) Reactants are less stable than products

A) Condensation reactions are anabolic

Which of the following best summarizes the relationship between condensation and hydrolysis reactions? A) Condensation reactions create polymers; hydrolysis reactions break down polymers B) ∆G is negative for condensation reactions; delta G is positive for hydrolysis reactions C) Condensation reactions break covalent bonds; hydrolysis reactions break hydrogen bonds D) Condensation reactions lead to greater entropy; hydrolysis reactions lead to less entropy E) Condensation reactions require a molecule of water; hydrolysis reactions produce a molecule of water

A) Condensation reactions create polymers; hydrolysis reactions break down polymers

Which of the following is false regarding a spontaneous reaction? A) Free energy of products is greater than free energy of reactants B) ∆G is negative C) Reactants are less stable than products D) Reactants are more ordered than products

A) Free energy of products is greater than free energy of reactants

What is an important adaptation that psychrophilic (cold loving) enzymes might have? A) Less rigid tertiary structure so that they maintain the flexibility to carry out their function. B) The melting point of the enzymes will be increased by a large number of disulfide bonds. C) The active site is smaller so that the rate of catalysis is faster. D) An increased number of ionic bonds to ensure that protein stability is not compromised. E) The number of hydrophobic amino acid side groups is increased in the active site because there is not enough energy in the system to form ionic and hydrogen bonds.

A) Less rigid tertiary structure so that they maintain the flexibility to carry out their function.

Which of the following statements is true? A) Spontaneous reactions have a negative ∆G. B) Spontaneous reactions occur at a rapid rate. C) Endergonic reactions have a negative ∆G. D) Non-spontaneous reactions only need enzymes for them to proceed forward.

A) Spontaneous reactions have a negative deltaG.

A hydrolysis reaction: A) Usually results in increased entropy. B) Is rarely an enzyme-mediated reaction in cells. C) Tends to occur slowly in a humid environment. D) Is a reaction in which the products have more free energy than the reactants. E) Tends to happen more efficiently at lower temperatures.

A) Usually results in increased entropy.

Conservation of energy, as stated in the first law of thermodynamics means that A) energy can neither be created nor destroyed B) energy can be destroyed but not created C) energy can be created but not destroyed D) energy can both be created and destroyed

A) energy can neither be created nor destroyed

All of the following are true about enzymes EXCEPT A) enzymes lower the ΔG of a chemical reaction B) enzymes bind their substrates non-covalently C) doubling the enzyme concentration will double reaction rate, provided substrate is unlimited D) enzymes decrease the activation energy needed to get a reaction going E) enzymes stabilize the transition state

A) enzymes lower the ΔG of a chemical reaction

Exergonic reactions A) have a negative ∆G. B) consume energy. C) have a positive ∆G. D) do not occur spontaneously.

A) have a negative ∆G.

Which of the following is the most accurate description of the role of an enzyme in catalyzing a biochemical reaction? A) Enzymes decrease the ∆G of the reaction, making it go faster B) Enzymes stabilize the transition state and decrease the free energy of the transition state C) Enzymes provide the activation energy necessary to reach the transition state D) Enzymes increase the amount of product formed

B) Enzymes stabilize the transition state and decrease the free energy of the transition state

In order to do an enzyme activity assay you must isolate your favorite enzyme from the cell. After isolating your enzyme you find that the active form of the enzyme is 6x the size that the primary structure would suggest. What is likely true about your enzyme? A) It has denatured and aggregated B) It has quaternary structure C) It has lost its original primary structure D) It has mostly beta-strand secondary structure E) It has denatured, but NOT aggregated

B) It has quaternary structure

Which of the following is true of a catabolic reaction? A) It is endergonic B) It leads to increased entropy C) Reactants have a lower free energy than products D) It has a +∆G

B) It leads to increased entropy

What must be TRUE of ALL of the chemical reactions that take place to link nucleotides together with a phosphodiester bond? A) Overall, the reactions must be endergonic since entropy is decreasing B) Overall, there will be both condensation and hydrolysis reactions C) Overall, the reactions will be exergonic because condensation reactions result in release of energy D) These reactions will only occur in organisms without a nucleus E) Overall, energy will be consumed

B) Overall, there will be both condensation and hydrolysis reactions

Condensation reactions, like the formation of a peptide bond: A) Tend to occur less efficiently when substrate concentration is in excess B) Tend to result in less entropy C) Tend NOT to be enzyme catalyzed reactions in biological systems D) Tend to occur more efficiently in a dry environment E) Tend to release energy

B) Tend to result in less entropy

The energy of activation A) is the same for most biochemical reactions. B) is the amount of energy required to reach a chemical reaction’s transition state. C) is the same as the ∆G for a spontaneous reaction. D) is the release of energy that occurs after a reaction is complete.

B) is the amount of energy required to reach a chemical reaction’s transition state.

Gibb's free energy represents A) the amount of energy consumed in a reaction. B) the energy available to do work. C) the total amount of energy. D) the amount of energy lost as heat.

B) the energy available to do work.

What occurs in the active site of an enzyme? A) It is where the reactants bind to the enzyme. B) It is the site where reactants are converted into products. C) All answer choices are correct statements about what can occur in the active site of an enzyme. D) Non-covalent interactions occur.

C) All answer choices are correct statements about what can occur in the active site of an enzyme.

A chemical reaction that has a positive ΔG is best described as _____. A) Exergonic B) Enthalpic C) Endergonic D) Spontaneous E) Entropic

C) Endergonic

Which of the following is not an example of an energy transformation? A) A chemical reaction converts the energy in sunlight into the chemical energy in glucose B) The electrical energy flowing through a lightbulb’s filament is converted into light and heat C) Sunlight strikes a prism and separates into distinct wavelengths D) A shoe drops, converting potential energy into kinetic energy

C) Sunlight strikes a prism and separates into distinct wavelengths

Which of the following statements about enzymes is not correct? A) Enzymes lower activation energy of a reaction B) Induced fit may occur, whereby the active site of the enzyme may undergo a slight change in shape when substrate binds C) The presence of an enzyme will change the outcome of a reaction D) Enzymes speed up the rate of a chemical reaction

C) The presence of an enzyme will change the outcome of a reaction

Which of the following is TRUE of an enzyme-catalyzed reaction vs the same reaction that happens in the absence of enzyme? A) The ∆G between the reactants and products is LESS in an enzyme-catalyzed reaction vs the same reaction that happens in the absence of enzyme. B) The energy of activation is the SAME in an enzyme-catalyzed reaction vs the same reaction that happens in the absence of enzyme. C) The ∆G between the reactants and products is the SAME in an enzyme-catalyzed reaction vs the same reaction that happens in the absence of enzyme. D) The energy of activation is HIGHER in an enzyme-catalyzed reaction vs the same reaction that happens in the absence of enzyme. E) The ∆G between the reactants and products is LARGER in an enzyme-catalyzed reaction vs the same reaction that happens in the absence of enzyme.

C) The ∆G between the reactants and products is the SAME in an enzyme-catalyzed reaction vs the same reaction that happens in the absence of enzyme.

Which statement is true about the reaction shown below? glucose 6-phosphate + H20 ⟶ glucose + Pi A) This reaction is an example of a condensation reaction. B) This reaction requires an input of energy for it to occur. C) This reaction has a negative ∆G D) This reaction is non-spontaneous.

C) This reaction has a negative ∆G

Thermal energy is A) mechanical energy B) the temperature increase that occurs when any form of energy is added to a system C) the kinetic energy of molecular motion, measured as heat D) a form of potential energy

C) the kinetic energy of molecular motion, measured as heat

Enthalpy represents A) the degree of disorder. B) the total amount of energy available to do work. C) the total amount of energy. D) the amount of energy lost as heat.

C) the total amount of energy.

Reactants capable of interacting to form products in a chemical reaction must first overcome a thermodynamic barrier known as the reaction's _____. A) Endothermic level B) Equilibrium point C) Free or Potential energy barrier D) Activation energy E) Entropy

D) Activation energy

Which statement about a chemical reaction's transition state is false? A) The transition state is highly unstable. B) An input of energy is required for reactants to reach the transition state. C) During the transition state, chemical bonds are breaking and new ones are forming. D) Enzymes do not affect the energy required to reach the transition state.

D) Enzymes do not affect the energy required to reach the transition state.

Which of the following reactions could be coupled to ATP hydrolysis to make it energetically favorable or spontaneous? ("to" is equivalent to an arrow) A) Glucose-1 phosphate + H2O to glucose + Pi ΔG= -5.0 B) Creatine phosphate + H20 to creatine + Pi ΔG = -3.0 C) Glucose + Pi to glucose-6 phosphate + H20 ΔG= +9.4 D) Glutamic acid + NH3 to glutamine ΔG=+3.

D) Glutamic acid + NH3 to glutamine ΔG=+3.

When coal is burned to produce electricity, the electrical energy produced is less than the potential energy of the coal. Which best explains this observation? A) As coal is heated, the molecules move so fast that they are destroyed B) Some of the energy in the coal is destroyed by the intense heat required to release its potential energy C) The amount of energy in the coal is not known D) Some of the potential energy in the coal is converted into forms of energy other than electricity

D) Some of the potential energy in the coal is converted into forms of energy other than electricity

When comparing an uncatalyzed reaction and the same reaction with a catalyst, which of the following is false? A) The catalyzed reaction will reach the transition state faster B) The catalyzed reaction will occur faster C) The catalyzed reaction will have a lower activation energy D) The catalyzed reaction will release more energy

D) The catalyzed reaction will release more energy

Which statement is false about the shown reaction? ATP + H2O ⟶ ADP + Pi A) It is an example of a hydrolysis reaction. B) The reaction releases energy. C) It is an exergonic reaction. D) The reaction requires an input of energy.

D) The reaction requires an input of energy.

Non-competitive inhibitors A) bind to the enzyme at the active site. B) can decrease the energy of activation. C) can activate an enzyme. D) bind to an enzyme at a site different than the active site.

D) bind to an enzyme at a site different than the active site.

Which of the following is true of a chemical reaction that splits a 6-carbon glucose molecule into two 3-carbon molecules (hydrolysis reaction)? A) the reaction results in decreased entropy B) the products in the reaction have the same free energy as the reactants C) the reactants are more stable than products D) the reaction is exergonic and therefore spontaneous E) the reaction is anabolic

D) the reaction is exergonic and therefore spontaneous

Which of the following would be most likely to destroy the primary structure of an enzyme? A) Competitive inhibitor B) Chaperone protein C) Denaturation D) Noncompetitive inhibitor E) Hydrolysis

E) Hydrolysis

You are studying enzyme "X" whose active site consists of 5 amino acids; 2 acidic amino acids and 3 amino acids with R-groups containing only non-polar covalent bonds. What chemical properties would you expect the substrate for enzyme "X" to have? A) Great capacity to form covalent bonds that would stabilize the substrate in the active site B) No capacity to make chemical interactions C) No capacity to make hydrogen bonds, but able to make hydrophobic interactions D) Hydrophobic and acidic properties E) Hydrophobic and basic properties

E) Hydrophobic and basic properties

Which of the following is true of hydration (hydrolysis) reactions? A) They are endergonic B) They lead to decreased entropy C) They have a positive delta Gibbs free energy D) Polymers are created from monomers E) They are catabolic

E) They are catabolic

The first law of thermodynamics states that energy cannot be created or destroyed. For living organisms, which of the following is an important consequence of the first law of thermodynamics? A) The entropy of any biological system is constant. B) The entropy of an organism decreases as the organism grows in complexity. C) Organisms grow by converting free energy into organic matter. D) The amount of potential energy in an organism is constant. E) Ultimately, all living organisms must acquire the energy needed for life from their environment.

E) Ultimately, all living organisms must acquire the energy needed for life from their environment.

You are running an enzyme catalyzed reaction in the presence of a non-competitive inhibitor. All of the following are true EXCEPT A) the inhibitor binds away from the active site, causing a conformational change in the protein B) the inhibitor binds to the enzyme reversibly C) the inhibitor typically binds to the enzyme non-covalently D) Vmax will always be lower in the presence of the inhibitor E) the effects of the inhibitor are decreased if substrate concentration is increased

E) the effects of the inhibitor are decreased if substrate concentration is increased