Deck 6: An Introduction to Energy, Enzymes, and Metabolism

Question 1

Which of the following represents two general factors that determine the fate of a chemical reaction in living cells?

A) its enzyme and rate
B) its enzyme and direction
C) its direction and rate
D) its rate and product
E) its enzyme and products

Answer 1

its direction and rate

Question 2

According to the first law of thermodynamics

A) the transfer of energy increases the disorder of a system.
B) the transfer of energy increases entropy.
C) energy cannot be created or destroyed.
D) once energy is created it can be destroyed.
E) kinetic energy is based on location.

Answer 2

energy cannot be created or destroyed.

Question 3

Which of the following is TRUE for a reaction that has a ? G< 0 ?

A) The reaction will require energy.
B) The reaction will yield energy.
C) The reaction is spontaneous.
D) The reaction will require energy and is spontaneous.
E) The reaction will yield energy and is spontaneous.

Answer 3

The reaction will yield energy and is spontaneous.

Question 4

hich is True of the following reaction: Pi+ADP?ATF?

A) It has a change in free energy that is less than 0.
B) It has a change in free energy that is greater than 0.
C) It can be used to drive endergonic reactions.
D) It yields energy.
E) It has a change in free energy that is greater than 0, and hence can be used to drive endergonic reactions.

Question 5

Which of the following statements about enzymes is FALSE?

A) The active site of the enzyme is where the chemical reaction takes place.
B) The substrate binds to the enzyme with low affinity.
C) The enzyme undergoes a conformational change that brings substrates closer together in an induced fit.
D) The optimal activity of an enzyme occurs over a narrow temperature range.
E) The optimal activity of an enzyme occurs within a narrow pH range.

Question 6

Which of the following would best reflect the general steps of an enzyme-catalyzed reaction?

A) enzyme undergoes conformational changes ? substrates bind to enzyme ? substrates are converted to products ? products are released.
B) substrates bind to enzyme ?substrates are converted to products ? enzyme undergoes conformational changes ? products are released
C) substrates bind to enzyme ? enzyme undergoes conformational changes ? substrates are converted to products ? products are released
D) enzyme undergoes conformational changes ?substrates are converted to products ? substrates bind to enzyme ? products are released
E) substrates bind to enzyme ? substrates are converted to products ? products are released ? enzyme undergoes conformational change

Question 7

Which of the following is NOT true for ATP?

A) It is produced from ATP synthase.
B) It is produced by a rotary machine.
C) Its production requires an exergonic reaction.
D) Its hydrolysis yields energy.
E) Its hydrolysis can drive endergonic reactions.

Question 8

Which of the following statements about catabolic reactions is FALSE?

A) They recycle organic building blocks.
B) They produce energy like ATP.
C) They produce energy in the form of energy intermediates like NADH.
D) They occur through the oxidation of substrates.
E) They usually require an input of energy.

Question 9

Which of the statements in INCORRECT about the following reaction? Phosphoenolpyruvate + ADP ? Pyruvate + ATP (?G = -7.5 kcal/mole)

A) It is anabolic.
B) It is catabolic.
C) It can be used to drive an endergonic reaction.
D) The synthesis of ATP occurs by substrate-level phosphorylation.
E) It is a reaction that yields energy.

Question 10

For the generalized equation Ae- +B ?A + Be-, where e represents an electron. Which of the following statements is TRUE?

A) Molecule A is reduced.
B) Molecule B is oxidzied.
C) Molecule A is oxidized.
D) Molecule B is reduced.
E) Both molecule A is oxidized and molecule B is reduced.

Question 11

Which of the following statements about feedback inhibition in metabolic pathways is most CORRECT?

A) The product of the pathway inhibits its own production by binding reactants in the metabolic pathway.
B) The product of the pathway inhibits its own production by competitively inhibiting the binding of a substrate to the active site of an enzyme within the metabolic pathway.
C) The product of the pathway inhibits its own production by noncompetitively inhibiting the binding of a substrate to the active site of an enyzme within the metabolic pathway.
D) The product of the pathway inhibits its own production by noncompetitively binding to reactants.
E) All of the choices are correct.

Question 12

In the biochemical regulation of metabolic pathways, how would one overcome the effects of a competitive inhibitor on enzyme activity?

A) Increase the amount of substrate for the enzyme.
B) Increase the amount of competitive inhibitor.
C) Increase the temperature of the reaction.
D) Decrease the amount of enzyme.
E) Add a noncompetitive inhibitor of the enzyme.

Question 13

Which of the following structures or molecular machines is important for protein degradation in eukaryotes?

A) cytoskeleton
B) flagellum
C) ribosome
D) ATP synthase
E) proteasome

Question 14

Which of the following statements about ubiquitin is TRUE?

A) Ubiquitin recognizes improperly folded proteins.
B) Ubiquitin targets proteins for degradation.
C) Ubiquitin targets proteins for post-translational processing.
D) Ubiquitin recognizes improperly folded proteins and targets them for degradation.
E) Ubiquitin targets proteins for degradation and post-translational processing.

Question 15

Which is the correct sequence of events for protein degradation in eukaryotes?

A) ubiquitin binds target protein ? protein unfolds and enters proteasome ? protein directed to proteasome ? protein digested ? amino acids are released and recycled
B) ubiquitin binds target protein ? protein directed to proteasome ? protein unfolds and enters proteasome ? protein digested ? amino acids are released and recycled
C) protein directed to proteasome ? ubiquitin binds target protein ? protein unfolds and enters proteasome ? protein digested ? amino acids are released and recycled
D) protein directed to proteasome ? protein unfolds and enters proteasome ? ubiquitin binds target protein ? protein digested ? amino acids are released and recycled
E) protein directed to proteasome ? protein unfolds and enters proteasome ? protein digested ? ubiquitin binds target protein ? amino acids are released and recycled

Question 16

Which two are primary complexes for protein synthesis and degradation in eukaryotes?

A) ribosomes and proteasomes
B) ribosomes and lysosomes
C) proteases and lysosomes
D) proteases and proteasomes
E) ribosomes and mRNA

Question 17

Reactions that produce glucose have less entropy than those that oxidize glucose.

Question 18

A reaction with a ?G > 0 is endergonic and requires a net input of energy.

Question 19

Noncompetitive inhibition within a metabolic pathway prevents excess accumulation of the pathway's product. This occurs when the product binds the active site of an enzyme, reducing its activity, and the subsequent accumulation of product.

Question 20

The half-life of a molecule is the time it takes for 50% of the molecule to be broken down and recycled.

Question 21

Autophagy is an important process that removes worn-out organelles, recycles components, then release them into the cytosol.