23 Questions
What is the value of Eo’tot for the reaction CoQ + H+ + NADH + 2e- CoQH2 + NAD+ + 2e?
$0.37 V$
What can be concluded about the energetically favorability of the reaction: Glutamate + NH4+ glutamine?
It is energetically unfavorable
In order to synthesize glutamine from glutamate and NH4+ in cells, what type of reaction can be coupled to make the process energetically favorable?
Hydrolysis of ATP
What is the standard free energy change ($ riangle G^{ heta}$) for the overall reaction: glutamate + NH4+ + ATP glutamine + ADP + Pi?
$-15.3 kJmol^{-1}$
What is the value of $ riangle G^{ heta}$ for the hydrolysis of ATP (Eqn 2)?
$-30.5 kJmol^{-1}$
What is required for Eo’tot to be positive in a reaction?
The overall reaction must have a positive standard reduction potential
What does a negative value of $ riangle G^{ heta}$ indicate about a reaction?
The reaction is energetically favorable.
What does a positive value of $ riangle G^{ heta}$ indicate about a reaction?
The reaction is energetically unfavorable.
What does a zero value of $ riangle G^{ heta}$ indicate about a reaction?
The reaction is at equilibrium.
In which case would a cell couple a non-spontaneous process with a spontaneous one?
To synthesize an energetically unfavorable molecule.
What is the relationship between the equilibrium constant (Keq) and the mass action ratio (Q)?
Keq = Q
Which molecule is the primary source of cellular energy?
ATP (adenosine triphosphate)
What drives endergonic reactions in cellular processes?
Hydrolysis of ATP
What is the primary reason for ATP having a large negative standard free energy change of hydrolysis?
Formation of stable products
How are phosphoryl-transfer reactions, such as the metabolism of glucose, driven?
By coupling exergonic and endergonic reactions
What is essential for biological redox reactions to occur spontaneously?
Transfer of electrons from higher to lower energy states
What is the standard state pressure in bar for studying Gibbs free energy change?
1 x $10^5$ Pa
What does the sign of $\triangle G$ tell us about a reaction?
The direction the reaction would have to go to reach equilibrium
What does a large value of equilibrium constant (K) indicate about a reaction?
The reaction favors the products
What can Gibbs free energy change ($\triangle G$) NOT provide information about?
Rate of the reaction
$\triangle G^{o'}$ represents the change in Gibbs free energy under which conditions?
'Standard state' conditions
Which type of reactions can provide information about the rate at which a reaction will proceed?
'Kinetics' reactions
$\triangle G^{o'}$ is used to represent the change in Gibbs free energy under standard state conditions, which include concentrations of how many mol dm$^{-3}$ for solutions?
1
Study Notes
- Equilibrium constant (Keq) describes the composition of a reaction mixture when at equilibrium. It is related to the mass action ratio (Q) through the equation: Keq = Q.
- Bioenergetics is essential for understanding various aspects of cellular functions, including metabolic processes, macromolecule structures, and membrane transport processes.
- Cellular reactions can be classified as spontaneous (exergonic) or non-spontaneous (endergonic). ATP (adenosine triphosphate), the primary source of cellular energy, is hydrolyzed to drive endergonic reactions.
- ATP has a large negative standard free energy change of hydrolysis, which results from the release of electrostatic repulsion, the formation of more stable products, and a small solvation energy for the hydrolysis products compared to ATP.
- Phosphoryl-transfer reactions, such as the metabolism of glucose and the synthesis of fatty acyl-CoA, are driven by the coupling of exergonic and endergonic reactions.
- Biological redox reactions, which involve the transfer of electrons, are essential for various cellular processes and must occur in pairs for the overall reaction to be spontaneous.
- Coenzymes, such as NADH and NADPH, serve as electron carriers in redox reactions and have different roles in cellular metabolism depending on their redox potentials and functional specialization.
- NADH and NADPH are derived from NAD+ and NADP+, respectively, and participate in various oxidation-reduction reactions as part of the electron transport chain.
- The mitochondrial electron transport chain is an essential component of cellular metabolism and involves the transfer of electrons between redox carriers, ultimately resulting in the generation of ATP through oxidative phosphorylation.
Test your knowledge of classical thermodynamics and its applications in living systems, especially in bioenergetics. This quiz covers the role of energy transfer molecules, coupled reactions, and spontaneity predictions in pharmacy-related contexts.
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