Ch. 14 HW Flashcards
The standard free energy change for the hydrolysis of ATP to ADP and inorganic phosphate (Pi) is about -30 kJ/mol but in the red blood cell the actual free energy change for this reaction is about -52 kJ/mol. This means that:
The concentration of inorganic phosphate is much lower that that of ADP.
The concentration of ATP is more than 1 M.
The concentration of ATP is greater than the product of the concentrations of ADP and Pi.
The product of the concentrations of ADP and Pi is greater than the concentration of ATP.
The concentration of ATP is greater than the product of the concentrations of ADP and Pi.
.
Which of the following is FALSE for catabolic pathways
They generate ATP.
They are oxidative.
They extract usable chemical energy from fuel molecules.
They generate oxidized enzyme cofactors.
They generate oxidized enzyme cofactors.
Correct Answer: Catabolic pathways generate reduced enzyme cofactors such as NADH and FADH2.
Which of the following is always involved in biological oxidation-reduction reactions?
Inner mitochondrial membrane.
Transfer of electron(s).
Oxygen.
Formation of water.
Transfer of electron(s).
Which of the following terms accurately describes an enzyme catalyzed pathway that can be both reductive and can extract usable chemical energy from fuel molecules?
Catabolic
Amphibolic
Anabolic
None of the above
Amphibolic
Which of the following statements concerning metabolic pathways is TRUE?
Metabolic pathways may have either a net positive or net negative free energy.
Opposing metabolic pathways do NOT occur.
Many of the reactions in a metabolic pathway are thermodynamically reversible.
All reactions in a metabolic pathway are tightly regulated.
Many of the reactions in a metabolic pathway are thermodynamically reversible
Which of the following phosphorylated compounds would be considered a “low-energy” intermediate in metabolism, relative to the others?
Glucose-6-phosphate
ATP
Phosphocreatine
1,3-Bisphosphoglycerate
Phosphoenolpyruvate
Glucose-6-phosphate
Which of the following terms accurately describes enzyme-catalyzed pathways that yield energy and breakdown complex molecules to simpler precursors?
Anabolic pathways
Metabolic pathways
Catabolic pathways
Amphibolic pathways
Catabolic pathways
Examine the following reactions:
Reaction 1. Glycerol 1-phosphate + H2O —-> Glycerol + Pi ∆G = -9
Reaction 2. ATP + H2O ——–> ADP + Pi + H+ ∆G = -30
What is the balanced equation and ∆G of the coupled reaction?
Glycerol + ATP —–> Glycerol 1-phosphate + ADP + H+ ∆G = -21
A hypothetical metabolic pathway is depicted below. A, B, C, D and E are the metabolic intermediates. E1 through E4 catalyze the 4 reactions. The free energy change for each reaction is shown below the arrow in kJ/mol. What MOST LIKELY happens if the concentration of metabolite C is increased?
The increased concentration of C will feedback inhibit enzyme E1.
The increased concentration of C will feed-forward activate enzyme E4.
The flux through the pathway from C to E will increase.
The reverse reaction C to B will be driven to equilibrium.
The flux through the pathway from C to E will increase.
True or False?
ΔGo and ΔGo’ mean the same thing.
False
True or False?
A ΔG value of zero indicates that the reactions or processes are at equilibrium.
True
*When a process is at equilibrium there is no net change in the concentration of reactants and products. Thus there is no change in free energy.
Under standard conditions is the oxidation of NADH by pyruvate sufficiently exergonic to drive the synthesis of ATP? Pick the statement below which best answers this question.
No, because the oxidation of NADH by pyruvate requires 25.1 kJ/mol of energy, which is endergonic.
Yes, because the oxidation of NADH by pyruvate generates -96.5 kJ/mol of energy.
No, because the oxidation of NADH by pyruvate only generates -25.1 kJ/mol of energy.
Yes, because the oxidation of NADH by pyruvate generates 96.5 kJ/mol of energy
No, because the oxidation of NADH by pyruvate only generates -25.1 kJ/mol of energy.
**ΔGo’ = -nF(ΔEo’) and ΔEo’ for NADH and pyruvate = 0.13V. This generates only -25.1 kJ/mol of energy which is insufficient to drive the synthesis of ATP.
Under standard conditions, the free energy change for the hydrolysis of phosphoarginine is – 32 kJ/mol. What is the actual free-energy change for the reaction at 25oC and pH 7.0 where the concentrations of phosphoarginine, arginine and Pi are 6.8 mM, 2.6 mM and 5 mM, respectively?
-47.5 kJ/mol
∆Go’ for the hydrolysis of ATP is – 31 kJ/mol. How will the magnitude of the standard free energy change alter if the pH increases to 8.0?
It will decrease.
It will stay the same.
It will increase.
It will stay the same.
** ∆Go’ is the standard free energy of the reaction, which does not change.
Fill in the blank
Cells carry out anabolic as well as catabolic pathways, with some enzymes functioning in both types of pathways. These enzymes catalyze near-equilibrium reactions because the direction of ________ depends on the relative concentrations of substrates and ___________. Consequently, these enzymes can catalyze both the _________ (e.g., anabolic) and__________ (e.g., catabolic) reactions.
flux; products; forward; reverse
