Hamdan- Bioenergetics
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Questions and Answers

What is the primary role of ATP in cellular metabolism?

  • To provide energy for unfavorable biochemical reactions (correct)
  • To facilitate the transfer of phosphate groups
  • To store energy from exergonic reactions
  • To act as a reducing agent in redox reactions

    • Which of the following statements about the free energy change ($\Delta G$) of a reaction is correct?

  • $\Delta G$ is constant for a given reaction, regardless of conditions
  • $\Delta G$ is additive for coupled reactions (correct)
  • $\Delta G$ is always negative for spontaneous reactions
  • $\Delta G$ is independent of substrate and product concentrations

    • What is the primary function of activated intermediates like ATP in metabolism?

  • To store energy from exergonic reactions
  • To facilitate the transfer of specific groups between molecules (correct)
  • To act as reducing agents in redox reactions
  • To increase the entropy of the system

    • What is the principle behind thermogenesis in living organisms?

    <p>Heat production is a consequence of exergonic reactions</p> Signup and view all the answers

    In a redox reaction, what determines the direction of electron flow?

    <p>The reduction potential of the oxidant and reductant</p> Signup and view all the answers

    What is the primary role of coenzyme A (CoA) in metabolism?

    <p>To facilitate the transfer of acyl groups</p> Signup and view all the answers

    What happens to the value of ΔG° when the equilibrium constant (K_eq) is greater than 1?

    <p>ΔG° is negative</p> Signup and view all the answers

    Which of the following statements about ΔG and K_eq is true?

    <p>ΔG is additive for multiple subsequent reactions, while K_eq is multiplicative</p> Signup and view all the answers

    When a stress is applied to a system at equilibrium, how does the equilibrium shift?

    <p>The equilibrium shifts to relieve the stress</p> Signup and view all the answers

    What is the effect of continuously supplying or removing a reactant or product on a metabolic reaction?

    <p>The reaction takes advantage of this effect to proceed</p> Signup and view all the answers

    How does an increase in temperature affect an endothermic reaction at equilibrium?

    <p>It favors the forward reaction</p> Signup and view all the answers

    What is the role of ATP in cellular energy transformations?

    <p>ATP both stores and releases energy for metabolic reactions</p> Signup and view all the answers

    What is the definition of bioenergetics according to the text?

    <p>The study of energy transformations in living cells and the chemical processes underlying them.</p> Signup and view all the answers

    According to the first law of thermodynamics, what happens to the total amount of energy in the universe during any change?

    <p>It remains constant.</p> Signup and view all the answers

    What does the second law of thermodynamics say about the tendency of the universe?

    <p>The universe always tends toward increasing disorder or entropy.</p> Signup and view all the answers

    What is the relationship between $ ext{Δ}G$ and $ ext{Δ}G^{o}$?

    <p>$ ext{Δ}G$ is affected by the concentration of reactants and products, while $ ext{Δ}G^{o}$ is not.</p> Signup and view all the answers

    What is the relationship between the combustion of glucose in a calorimeter and the conversion of glucose to CO2 and H2O in a cell?

    <p>The energy released is the same in the two processes.</p> Signup and view all the answers

    How does $ ext{Δ}G$ measure the tendency of a reaction to proceed towards equilibrium?

    <p>$ ext{Δ}G$ measures the spontaneity of the reaction, with negative values indicating a spontaneous reaction.</p> Signup and view all the answers

    Which equation represents the relationship between the standard free-energy change (Go) and the equilibrium constant (Keq)?

    <p>$ext{}G^{o} = RText{ln}ext{K}_{eq}$</p> Signup and view all the answers

    What is the value of G when the concentrations of reactants and products are both 1 mol/L?

    <p>G = Go</p> Signup and view all the answers

    What is the sign of G when the reaction is at equilibrium?

    <p>G is zero</p> Signup and view all the answers

    What is the relationship between the sign of Go and the value of the equilibrium constant (Keq)?

    <p>If Go is negative, then Keq &lt; 1</p> Signup and view all the answers

    What is the value of G when the concentrations of glucose 6-phosphate and fructose 6-phosphate are 0.66 mol/L and 0.33 mol/L, respectively?

    <p>G = Go + RT ln (0.33/0.66)</p> Signup and view all the answers

    What is the sign of G when the reaction is not at equilibrium?

    <p>G can be positive, negative, or zero</p> Signup and view all the answers

    What is the relationship between G and the direction of a reaction?

    <p>A negative G means the reaction is spontaneous</p> Signup and view all the answers

    Can a reaction have a positive Go and still be favorable?

    <p>Yes, if the reaction is coupled to another favorable reaction</p> Signup and view all the answers

    What does the second law of thermodynamics state?

    <p>The universe always tends toward increasing disorder (or entropy).</p> Signup and view all the answers

    Which statement about $\Delta G$ is true?

    <p>$\Delta G$ is a state function that depends only on the initial and final states.</p> Signup and view all the answers

    What is the relationship between $\Delta G$ and the spontaneity of a reaction?

    <p>A negative $\Delta G$ indicates a spontaneous reaction.</p> Signup and view all the answers

    What is the effect of increasing the concentration of products on the value of $\Delta G$?

    <p>$\Delta G$ increases.</p> Signup and view all the answers

    What does the first law of thermodynamics state?

    <p>For any change, the total amount of energy in the universe remains constant.</p> Signup and view all the answers

    What is the relationship between $\Delta G^{\circ}$ and the equilibrium constant ($K_{eq}$)?

    <p>All of the above.</p> Signup and view all the answers

    What is the concept of activation energy?

    <p>The energy required to initiate a chemical reaction.</p> Signup and view all the answers

    What is the relationship between the combustion of glucose in a calorimeter and the conversion of glucose to CO2 and H2O in a cell?

    <p>The $\Delta G$ values are the same.</p> Signup and view all the answers

    Where in the body are mitochondria found in the greatest number?

    <p>Eye, brain, heart, and muscle</p> Signup and view all the answers

    What is the primary function of mitochondria?

    <p>ATP production</p> Signup and view all the answers

    Why is ATP considered a high-energy molecule?

    <p>It has an intermediate energy value, allowing it to be coupled to other reactions</p> Signup and view all the answers

    Which of the following statements about ATP is true?

    <p>It is recycled as food in cells is gradually oxidized</p> Signup and view all the answers

    What is the total daily ATP turnover in the human body, in grams?

    <p>49,920 g</p> Signup and view all the answers

    Which of the following statements about biochemical reactions and pathways is true?

    <p>They are coordinated by sensitive means of communication</p> Signup and view all the answers

    Which of the following is an example of an exergonic reaction or pathway in biochemistry?

    <p>Oxidation of glucose with oxygen to carbon dioxide and water</p> Signup and view all the answers

    How do cells obtain energy for unfavorable biochemical work?

    <p>By coupling unfavorable reactions to exergonic reactions</p> Signup and view all the answers

    Which of the following is true about the free energy change ($\Delta$G) of a reaction?

    <p>$\Delta$G depends on the concentrations of reactants and products, not just on temperature and pressure.</p> Signup and view all the answers

    What is the primary role of ATP in cellular metabolism?

    <p>To store energy from exergonic reactions for use in endergonic reactions.</p> Signup and view all the answers

    What is the primary function of activated intermediates like ATP in metabolism?

    <p>To store energy for later use in endergonic reactions.</p> Signup and view all the answers

    What is the principle behind thermogenesis in living organisms?

    <p>Thermogenesis is the process of generating heat as a byproduct of metabolism.</p> Signup and view all the answers

    What is the relationship between $\Delta$G and $\Delta$G$^{\circ}$?

    <p>$\Delta$G = $\Delta$G$^{\circ}$ + RT ln K$<em>{eq}$, where K$</em>{eq}$ is the equilibrium constant.</p> Signup and view all the answers

    What is the primary role of coenzyme A (CoA) in metabolism?

    <p>To act as a universal carrier of acyl groups.</p> Signup and view all the answers

    In a redox reaction, what determines the direction of electron flow?

    <p>The reduction potentials of the oxidant and reductant.</p> Signup and view all the answers

    What is the relationship between the combustion of glucose in a calorimeter and the conversion of glucose to CO2 and H2O in a cell?

    <p>The combustion in a calorimeter measures the total energy released, while the cellular process measures the free energy change.</p> Signup and view all the answers

    What is the relationship between the Gibbs free energy change ($\Delta G^{\circ}$) and the equilibrium constant ($K_{eq}$)?

    <p>$\Delta G^{\circ} = - RT \ln K_{eq}$</p> Signup and view all the answers

    How does the value of $\Delta G^{\circ}$ change with respect to the equilibrium constant ($K_{eq}$)?

    <p>All of the above statements are true</p> Signup and view all the answers

    What happens to the equilibrium of a reaction when a reactant or product is continuously supplied or removed?

    <p>The equilibrium shifts to favor the formation of more products</p> Signup and view all the answers

    How does an increase in temperature affect an endothermic reaction at equilibrium?

    <p>It favors the forward reaction</p> Signup and view all the answers

    What is the effect of a catalyst on an equilibrium reaction?

    <p>It has no effect on the equilibrium position</p> Signup and view all the answers

    What is the role of ATP in cellular metabolism?

    <p>It acts as a carrier of energy for metabolic reactions</p> Signup and view all the answers

    According to the first law of thermodynamics, what happens to the total amount of energy in the universe during any change?

    <p>The total amount of energy remains constant</p> Signup and view all the answers

    What is the primary role of coenzyme A (CoA) in metabolism?

    <p>It is a carrier of acetyl groups and other acyl groups</p> Signup and view all the answers

    Study Notes

    Principles of Bioenergetics

    Definition and Biological Energy Transformations

    • Bioenergetics: the quantitative study of energy transductions in living cells and the chemical processes underlying these transductions
    • Biological energy transformations obey the laws of thermodynamics

    Laws of Thermodynamics

    • First law: total amount of energy in the universe remains constant
    • Second law: universe tends toward increasing disorder (entropy increases)

    Why Do Chemical Reactions Occur?

    • Concept of activation energy
    • ∆G and ∆Go: measures of the tendency of a reaction to proceed towards equilibrium
    • ∆G is affected by concentration of reactants and products

    Phosphoryl Group Transfers and ATP

    • Energy flow: ingestion, digestion, absorption, metabolism (Acetyl CoA), TCA, oxidative phosphorylation
    • Coupling concept: phosphoryl transfer reactions
    • Activated intermediates: phosphoryl groups, ATP, UTP, CTP, GTP

    Thermogenesis

    • First law of thermodynamics
    • Heat production is a natural consequence of "burning fuels"
    • Thermogenesis: energy expended for generating heat
    • Shivering thermogenesis
    • Non-shivering thermogenesis

    Biological Oxidation-Reduction Reactions (Redox)

    • Oxidation: gain of oxygen, loss of hydrogen, loss of electrons
    • Reduction: gain of hydrogen, gain of electron, loss of oxygen
    • E (redox Potential): measures the tendency of oxidant/reductant to gain/lose electrons
    • Electrons move from compounds with lower reduction potential to compounds with higher reduction potential

    ATP and Energy Metabolism

    • ATP is the energy currency of the cell
    • High energy molecule with intermediate energy value
    • ATP is not a good long-term energy storage molecule
    • Tissue ATP turnover: brain, heart, kidney, liver, muscle

    Biochemical Reactions and Pathways

    • Interdependent reactions subjected to thermodynamics laws
    • Coordinated by sensitive means of communication
    • Allosteric enzymes are the predominant regulators
    • Pathways are linear, cyclic, or spiral

    Exergonic Reactions and Pathways

    • Complex structures → simple structures
    • Hydrolysis reactions
    • Decarboxylation reactions (release pyruvate → acetyl-CoA)
    • Oxidation with O2 of CO2)

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    Description

    Explore the concepts of bioenergetics and thermodynamics in living cells, focusing on energy transductions and chemical processes. Learn how biological energy transformations adhere to the laws of thermodynamics, including the conservation of energy and the tendency towards increased disorder.

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