10 Principles Of Bioenergetics

If the ΔG'° of the reaction A → B is -100 kJ/mol, under standard conditions the reaction:

• Is at equilbirum

• Will never reach equilibrium

• Will not occur spontaneously

• Will proceed at a rapid rate

• Will proceed spontaneously from left to right

Which is INCORRECT?  Energy is required by cells for:

• Transport of molecules or ions against a concentration gradient

• Synthesis of new chemical bonds

• Maintenance of body temperature

• Mechanical movement

• Hydrolysis of a molecule during an exothermic reaction

Which is NOT a mechanism for regulating metabolic pathways?

• Control of intracellular substrate concentration

• Control of allosteric enzymes by inhibitors and activators

• Control of cell temperature

• Control of amount of enzymes

• Control of enzymes through signalling substances (e.g. hormones)

If the ΔG'° of the reactions A → B is +20kJ/mol, under standard conditions the reaction:

• Will proceed spontaneously from right to left

• Will proceed spontaneously from left to right

• Will never reach equilbrium

• Will proceed to equilibrium at a rapid rate

• Is currently at equilibrium

What is the standard-state free energy (ΔG°) for the hydrolysis of ATP to ADP? 

• +45.6 kJ/mol

• -45.6 kJ/mol

• -30.5 kJ/mol

• 15.6 kJ/mol

• 12.2 kJ/mol

Reciprocal regulation refers to:

• The division of energy from the catalytic pathway by the anabolic pathway

• The opposite reaction type that is being referred to

• The ability of cells to simultaneously activate anabolic and catabolic reactions

• The ability of cells to simultaneously inactive anabolic and catabolic reactions

• Activation of one pathway, while suppressing the opposite pathway

When a mixture containing an equal concentration of glucose 6-phosphate and fructose 6-phosphate is incubated with the enzyme phosphohexose isomerase, the final mixture contains twice as much glucose 6-phosphate as fructose 6-phosphate.  Which one of the following statements is correct, when applied to the reaction below (R = 8.315 J/mol•K and T = 298 K)? Glucose 6-phosphate ↔ fructose 6-phosphate

• ΔG'° is +1.7 kJ/mol

• ΔG'° is –1.7 kJ/mol

• ΔG'° is incalculably large and negative

• ΔG'° is incalculably large and positive

• ΔG'° is zero

Given the following information, calculate the actual free energy of the below reaction. A → B;  K_eq = 10; concentration in the cell of A = 0.2 M; B = 0.05 M; R = 8.315 J/mol.K; T = 298 K?

• -9.1 kJ/mol

• -15.8 kJ/mol

• -200.2 kJ/mol

• +22.5 kJ/mol

• 0 kJ/mol

Which is NOT true about the following reactions?A → B   ΔG = +20 kJ/mol = reaction 1C → D   ΔG = –30 kJ/mol = reaction 2 A + C → B + D = reaction 3 

• Reaction 1 will proceed from right to left

• Reaction 2 will proceed from left to right

• Reaction 3, the sum of reaction 1 and 2, will occur spontaneously with overall free energy of –10 kJ/mol

• Reaction 1 will not proceed from left to right unless an enzyme is present

• Reaction 2 will proceed spontaneously

Describe why anabolism and catabolism need to be precisely regulated. Include in your answer what is meant by reciprocal regulation of anabolic and catabolic pathways.

Describe using an equation, how a reaction in a biochemical pathway may occur spontaneously despite the standard free energy for that reaction being positive. Outline the difference between free energy and standard free energy in your answer.