L15 Bioenergetics Part 1 of 2

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Question #1

In the cell, ATP carries 4 positive charges.

A TRUE

B FALSE

Question #2

The breakdown of a “super-high-energy compound”, can release the energy necessary for the synthesis of ATP from ADP and Pi.

A TRUE

B FALSE

Question #3

A phosphorylated compound is considered a high energy compound.

A TRUE

B FALSE

Question #4

The formation of ATP (or GTP) by the direct transfer of a phosphoryl group to ADP (or GDP) is called substrate level phosphatase.

A TRUE

B FALSE

Question #5

ATP has the highest phosphoryl-transfer potential among phosphoryl containing molecules.

A FALSE

B TRUE

Question #6

Inorganic polyphosphate is store in the cytosol.

A FALSE

B TRUE

Question #7

The binding of magnesium to ATP makes the hydrolysis reaction more exergonic.

A FALSE

B TRUE

Question #8

Magnesium is a coenzyme.

A TRUE

B FALSE

Question #9

Phosphorylation reactions are catalyzed by kinases.

A FALSE

B TRUE

Question #10

Phosphorylation usually occurs when the phosphorous of the phosphoryl group reacts with an electrophile, such a the oxygen of an hydroxyl group of an alcohol.

A TRUE

B FALSE

Question #11

The transfer of a phosphoryl group to a compound puts free energy into that compound, making it more stable.

A TRUE

B FALSE

Question #12

The orthophosphate ion is stabilized by resonance.

A FALSE

B TRUE

Question #13

The repulsion between the four negative charges of the phosphate groups is greater in the reactants of the hydrolysis reaction of ATP.

A FALSE

B TRUE

Question #14

The products of hydrolysis of ATP are more unstable that ATP

A TRUE

B FALSE

Question #15

Pyrophosphate contains

A one phosphate

B three phosphates

C four phosphates

D two phosphates

Question #16

The hydrolysis of one mole GTP provides 30 kJ in standard conditions.

A TRUE

B FALSE

Question #17

The free energy necessary for the synthesis of ATP is provided when carbon containing molecules undergo exergonic reactions such as oxidation reactions.

A TRUE

B FALSE

Question #18

The synthesis of ATP from ADP and Pi is an endergonic reaction.

A FALSE

B TRUE

Question #19

Hydrolysis of the alpha phosphate group release the largest amount of energy

A FALSE

B TRUE

Question #20

ATP contains

A 3 phosphate groups

B 3 phosphoanhydride bonds

Question #21

ATP can be stored for long time and then used but the cell to provide chemical energy

A TRUE

B FALSE

Question #22

The hydrolysis of ATP

A releases energy

B absorbs energy

Question #23

The energy of ATP is

A chemical energy

B thermal energy

C atomic energy

D chemical potential energy

Question #24

The positive value of ΔG°’ predicts that, in any conditions, the reaction will tend not to proceed spontaneously in the direction written.

A TRUE

B FALSE

Question #25

The free energy changes of reactions that have a common intermediate can be multiplied to provide the total free energy change.

A FALSE

B TRUE

Question #26

The free-energy change depends both on the nature and the initial concentration of reactants and products.

A FALSE

B TRUE

Question #27

Decreasing the concentration of reactants ensure that a reaction is spontaneous in the backwards direction.

A TRUE

B FALSE

Question #28

Decreasing the concentration of products ensure that a reaction is spontaneous in the forward direction.

A TRUE

B FALSE

Question #29

Changing the energy of the reactants or the products is a cellular strategy to increase to spontaneity of a reaction.

A TRUE

B FALSE

Question #30

The conditions inside a cell or organism can be very different from these standard conditions, so ∆G values for biological reactions in vivo may vary widely from their standard free energy change (ΔG°’) values.

A TRUE

B FALSE

Question #31

The standard free energy change is often measured in kjoules or kcalories.

A TRUE

B FALSE

Question #32

A value of equilibrium constant equal to 4.3 x 10-2 corresponds to a non-spontaneous reaction.

A FALSE

B TRUE

Question #33

A spontaneous reactions has a large equilibrium constant.

A FALSE

B TRUE

Question #34

If a reaction is exergonic converting reactants to products, then it’s be endergonic converting products to reactants.

A FALSE

B TRUE

Question #35

When, during a chemical reaction, the system changes so as to possess more free energy, the free-energy change has a positive value and the reaction is said to be exergonic.

A TRUE

B FALSE

Question #36

When a reaction proceeds with a net release of free energy, the free-energy change has a positive value and the reaction is said to be exergonic.

A TRUE

B FALSE

Question #37

Which of the following serves as the “chemical currency” of metabolism?

A NADH

B acetyl CoA

C glucose

D ATP

E NADPH

Question #38

The hydrolysis of ATP has a large negative ∆G’°; nevertheless it is stable in solution due to:

A ionization of the phosphates.

B resonance stabilization.

C entropy stabilization.

D the hydrolysis reaction being endergonic.

E the hydrolysis reaction having a large activation energy.

Question #39

All of the following contribute to the large, negative, free-energy change upon hydrolysis of “high-energy” compounds except:

A stabilization of products by solvation.

B low activation energy of forward reaction.

C stabilization of products by ionization.

D electrostatic repulsion in the reactant.

E stabilization of products by extra resonance forms.

Question #40

The standard free-energy changes for the reactions below are given.
Phosphocreatine -> creatine + Pi ∆G’° = –43.0 kJ/mol
ATP -> ADP + Pi ∆G’° = –30.5 kJ/mol
What is the overall ∆G’° for the following reaction?
Phosphocreatine + ADP -> creatine + ATP

A +73.5 kJ/mol

B +12.5 kJ/mol

C ∆G’° cannot be calculated without Keq’.

D –12.5 kJ/mol

E –73.5 kJ/mol

Question #41

During glycolysis, glucose 1-phosphate is converted to fructose 6-phosphate in two successive reactions:
Glucose 1-phosphate -> glucose 6-phosphate ∆G’° = –7.1 kJ/mol
Glucose 6-phosphate -> fructose 6-phosphate ∆G’° = +1.7 kJ/mol
∆G’° for the overall reaction is:

A –7.1 kJ/mol.

B –5.4 kJ/mol.

C +5.4 kJ/mol.

D –8.8 kJ/mol.

E +8.8 kJ/mol.

Question #42

For the following reaction, ∆G’° = +29.7 kJ/mol.
L-Malate + NAD+ -> oxaloacetate + NADH
The reaction as written:

A cannot occur because of its large activation energy.

B can occur only in a cell in which NADH is converted to NAD+ by electron transport.

C can occur in a cell only if it is coupled to another reaction for which ∆G’° is positive.

D can never occur in a cell.

E may occur in cells at some concentrations of substrate and product.

Question #43

The reaction A + B -> C has a ∆G’° of –20 kJ/mol at 25° C. Starting under standard conditions, one can predict that:

A at equilibrium, the concentration of C will be less than the concentration of A.

B at equilibrium, the concentration of B will exceed the concentration of A.

C at equilibrium, the concentration of C will be much greater than the concentration of A or B.

D C will rapidly break down to A + B.

E when A and B are mixed, the reaction will proceed rapidly toward formation of C.

Question #44

Hydrolysis of 1 M glucose 6-phosphate catalyzed by glucose 6-phosphatase is 99% complete at equilibrium (i.e., only 1% of the substrate remains). Which of the following statements is most nearly correct? (R = 8.315 J/mol·K; T = 298 K)

A ∆G’° is –11 kJ/mol.

B ∆G’° is 0 kJ/mol.

C ∆G’° is –5 kJ/mol.

D ∆G’° is +11 kJ/mol.

E ∆G’° cannot be determined from the information given.

Question #45

When a mixture of glucose 6-phosphate and fructose 6-phosphate is incubated with the enzyme phosphohexose isomerase (which catalyzes the interconversion of these two compounds) until equilibrium is reached, the final mixture contains twice as much glucose 6-phosphate as fructose 6-phosphate. Which one of the following statements is best applied to this reaction outlined below? (R = 8.315 J/mol·K; T = 298 K)
Glucose 6-phosphate -> fructose 6-phosphate

A ∆G’° is incalculably large and positive.

B ∆G’° is incalculably large and negative.

C ∆G’° is +1.72 kJ/mol.

D ∆G’° is zero.

E ∆G’° is –1.72 kJ/mol.

Question #46

When a mixture of 3-phosphoglycerate and 2-phosphoglycerate is incubated at 25 °C with phosphoglycerate mutase until equilibrium is reached, the final mixture contains six times as much 2-phosphoglycerate as 3-phosphoglycerate. Which one of the following statements is most nearly correct, when applied to the reaction as written? (R = 8.315 J/mol·K; T = 298 K)
3-Phosphoglycerate -> 2-phosphoglycerate

A ∆G’°is incalculably large and positive.

B ∆G’° is –4.44 kJ/mol.

C ∆G’° cannot be calculated from the information given.

D ∆G’°is +12.7 kJ/mol.

E ∆G’° is zero.

Question #47

If the ∆G’° of the reaction A -> B is –40 kJ/mol, under standard conditions the reaction:

A will not occur spontaneously

B will proceed spontaneously from A to B

C will proceed at a rapid rate

D is at equilibrium

E will never reach equilibrium

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L15 Bioenergetics Part 1 of 2

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