Exam 13: Principles of Bioenergetics

During transfer of two electrons through the mitochondrial respiratory chain,the overall reaction is: NADH + 1/2 O₂ + H⁺ $\rightarrow$ NAD⁺ + H₂O For this reaction,the difference in reduction potentials for the two half-reactions ( $\Delta$ E'°)is +1.14 V.Show how you would calculate the standard free-energy change, $\Delta$ G'°,for the reaction.(The Faraday constant,,is 96.48 kJ/V·mol. )

Classify each of the *ed atoms as an electrophile or a nucleophile:

The immediate precursors of DNA and RNA synthesis in the cell all contain:

Explain in quantitative terms the circumstances under which the following reaction can proceed. Citrate $\rightarrow$ isocitrate $\Delta$ G'° = +13.3 kJ/mol

Which one of the following compounds does not have a large negative free energy of hydrolysis?

The reaction ATP $\rightarrow$ ADP + P_i is an example of a reaction.

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 $\rightarrow$ 2-phosphoglycerate

The first law of thermodynamics states that the amount of energy in the universe is constant,but that the various forms of energy can be interconverted.Describe four different types of such energy transduction that occur in living organisms and provide one example for each.

Consider the reaction: A + B $\rightarrow$ C + D.If the equilibrium constant for this reaction is a large number (say,10,000),what do we know about the standard free-energy change ( $\Delta$ G'°)for the reaction? Describe the relationship between K_eq' and $\Delta$ G'°.

The free energy of hydrolysis of phosphoenolpyruvate is -61.9 kJ/mol.Rationalize this large,negative value for $\Delta$ G'° in chemical terms.

The expression $\Delta$ G = $\Delta$ G'° + RT ln K_eq' for the actual free-energy change for the reaction A + B $\rightarrow$ C + D is incorrect.Why is it wrong,and what is the correct expression for the real free-energy change of this reaction?

Which of the following is not true?

E'° of the NAD⁺/NADH half reaction is -0.32 V.The E'° of the oxaloacetate/malate half reaction is -0)175 V.When the concentrations of NAD⁺,NADH,oxaloacetate,and malate are all 10^-5 M,the "spontaneous" reaction is:

During glycolysis,glucose 1-phosphate is converted to fructose 6-phosphate in two successive reactions: Glucose 1-phosphate $\rightarrow$ glucose 6-phosphate $\Delta$ G'° = -7.1 kJ/mol Glucose 6-phosphate $\rightarrow$ fructose 6-phosphate $\Delta$ G'° = +1.7 kJ/mol $\Delta$ G'° for the overall reaction is:

Glycerol 3-phosphate dehydrogenase catalyzes the following reversible reaction: Glycerol 3-phosphate + NAD⁺ $\rightarrow$ NADH + H⁺ + dihydroxyacetone phosphate Given the standard reduction potentials below,calculate $\Delta$ G'° for the glycerol 3-phosphate dehydrogenase reaction,proceeding from left to right as shown.Show your work.(The Faraday constant,F,is 96.48 kJ/V·mol. )

For each pair of ions or compounds below,indicate which is the more highly reduced species. (a)Co²⁺/Co⁺ (b)Glucose/CO₂ (c)Fe³⁺/Fe²⁺ (d)Acetate/CO₂ (e)Ethanol/acetic acid (f)Acetic acid/acetaldehyde

The standard reduction potentials (E'°)for the following half reactions are given. Fumarate + 2H⁺ + 2e^- $\rightarrow$ succinate E'° = +0.031 V FAD + 2H⁺ + 2e^- $\rightarrow$ FADH₂ E'° = -0.219 V If you mixed succinate,fumarate,FAD,and FADH₂ together,all at l M concentrations and in the presence of succinate dehydrogenase,which of the following would happen initially?

Which of the following is true about oxidation-reduction reactions?

In glycolysis,the enzyme pyruvate kinase catalyzes this reaction: Phosphoenolpyruvate + ADP $\rightarrow$ pyruvate + ATP Given the information below,show how you would calculate the equilibrium constant for this reaction.(R = 8.315 J/mol·K;T = 298 K) Reaction 1)ATP $\rightarrow$ ADP + P_i $\Delta$ G'° = -30.5 kJ/mol Reaction 2)phosphoenolpyruvate $\rightarrow$ pyruvate + P_i $\Delta$ G'° = -61.9 kJ/mol

If $\Delta$ E'° for an oxidation-reduction reaction is positive,will $\Delta$ G'° be positive or negative? What is the equation that relates $\Delta$ G'° and $\Delta$ E'°?