Harper's Biochemistry Chapter 11 - Bioenergetics
94 Questions
5 Views

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to lesson

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What does a negative ΔG indicate about a reaction?

  • The reaction proceeds spontaneously. (correct)
  • The reaction requires an input of energy.
  • The reaction is at equilibrium.
  • The reaction occurs with a gain of free energy.

    • In the equation ΔG = ΔH - TΔS, what does ΔH represent?

  • The absolute temperature.
  • The change in enthalpy. (correct)
  • The change in free energy.
  • The change in entropy.

    • When ΔG is positive, what can be concluded about the reaction?

  • It is exergonic.
  • It is at equilibrium.
  • It will occur spontaneously.
  • Free energy must be supplied for it to proceed. (correct)

    • Which of the following best describes an endergonic reaction?

    <p>It occurs with a gain of free energy.</p> Signup and view all the answers

    What occurs if ΔG is zero?

    <p>The system is at equilibrium.</p> Signup and view all the answers

    Which term is used to indicate a process accompanied by a loss of free energy?

    <p>Exergonic.</p> Signup and view all the answers

    Which of the following statements is true regarding the relationship between ΔH and ΔE?

    <p>ΔH is approximately equal to ΔE.</p> Signup and view all the answers

    What influences the extent to which a reaction proceeds to completion?

    <p>The magnitude of ΔG.</p> Signup and view all the answers

    What is the primary source of free energy for heterotrophic organisms?

    <p>Breakdown of complex organic molecules</p> Signup and view all the answers

    Which component of ATP is directly involved in energy transfer processes?

    <p>The phosphate groups</p> Signup and view all the answers

    What is the role of Mg2+ in the context of ATP?

    <p>It functions as a cofactor for the reaction.</p> Signup and view all the answers

    Which of the following compounds has the highest standard free energy of hydrolysis?

    <p>Phosphoenolpyruvate</p> Signup and view all the answers

    Which nucleotide is made up of adenosine and three phosphate groups?

    <p>Adenosine triphosphate (ATP)</p> Signup and view all the answers

    Which compound has the lowest standard free energy of hydrolysis?

    <p>Creatine phosphate</p> Signup and view all the answers

    What role do phosphates play in intermediary metabolism?

    <p>They are involved in energy transfer reactions.</p> Signup and view all the answers

    Which process is primarily associated with ATP, ADP, and inorganic phosphate (Pi)?

    <p>Glycolysis</p> Signup and view all the answers

    What is the significance of understanding the standard free energy of hydrolysis of organophosphates?

    <p>It is crucial for understanding energy transfer dynamics in metabolism.</p> Signup and view all the answers

    What does the standard free-energy change ΔG0′ represent in biochemical reactions?

    <p>The standard free-energy change at a defined pH of 7.0</p> Signup and view all the answers

    Which term describes the breakdown or oxidation of fuel molecules in biochemical processes?

    <p>Catabolism</p> Signup and view all the answers

    What is the relationship between exergonic and endergonic reactions in a coupled system?

    <p>Exergonic reactions drive the overall process of endergonic reactions</p> Signup and view all the answers

    How is the actual free energy change (ΔG) different from the standard free-energy change (ΔG0′)?

    <p>ΔG can vary based on reactant concentrations</p> Signup and view all the answers

    What role does an enzyme play in biochemical reactions?

    <p>It speeds up the approach to equilibrium without changing final concentrations</p> Signup and view all the answers

    Which equation describes the standard free-energy change in relation to the equilibrium constant?

    <p>ΔG0′ = -RT ln Keq</p> Signup and view all the answers

    What must happen for an endergonic process to proceed in a biochemical system?

    <p>It must be coupled with an exergonic reaction</p> Signup and view all the answers

    In a coupled exergonic–endergonic system, what component facilitates the reaction?

    <p>A common obligatory intermediate</p> Signup and view all the answers

    What do anabolic processes primarily involve in metabolism?

    <p>Building up substances and synthesizing new molecules</p> Signup and view all the answers

    In the equation ΔG0′ = -RT ln Keq, what does the variable R represent?

    <p>The universal gas constant</p> Signup and view all the answers

    What happens to AMP concentration when ATP is depleted?

    <p>AMP concentration increases to signal an increase in catabolic reactions.</p> Signup and view all the answers

    Which compound is produced when ATP is hydrolyzed directly to AMP?

    <p>Inorganic pyrophosphate (PPi)</p> Signup and view all the answers

    What is the role of inorganic pyrophosphatase in ATP hydrolysis?

    <p>It facilitates the hydrolytic splitting of PPi.</p> Signup and view all the answers

    What energy change is associated with the activation of long-chain fatty acids?

    <p>A decrease in free energy, releasing heat.</p> Signup and view all the answers

    Which process is catalyzed by adenylyl kinase?

    <p>Formation of NDP from corresponding monophosphates.</p> Signup and view all the answers

    What is primarily required to initiate the hydrolysis of ATP?

    <p>Energy to destabilize the molecule</p> Signup and view all the answers

    What stabilizes the orthophosphate produced from ATP hydrolysis?

    <p>Formation of resonance hybrids</p> Signup and view all the answers

    What is the relationship between the hydrolysis of ATP and the release of energy?

    <p>Net energy is released due to destabilization of the molecule</p> Signup and view all the answers

    Which process is considered the greatest source of ATP in aerobic organisms?

    <p>Oxidative phosphorylation</p> Signup and view all the answers

    What effect do negatively charged oxygen atoms have on ATP?

    <p>They create strong electrostatic repulsion</p> Signup and view all the answers

    How long can the total ATP/ADP pool maintain an active tissue?

    <p>For only a few seconds</p> Signup and view all the answers

    What role does the respiratory chain play in ATP production?

    <p>It facilitates the reduction of O2 to H2O</p> Signup and view all the answers

    What is the consequence of breaking the P-O bond in ATP?

    <p>Release of net energy due to electrostatic changes</p> Signup and view all the answers

    What is meant by 'resonance hybrids' in the context of orthophosphate stabilization?

    <p>Equal sharing of negative charges between oxygen atoms</p> Signup and view all the answers

    Which of the following statements about ADP is true?

    <p>ADP is produced when ATP is hydrolyzed</p> Signup and view all the answers

    What effect does the breaking of the P-O bond in ATP primarily have on the molecule?

    <p>It relieves electrostatic repulsion among negatively charged oxygen atoms.</p> Signup and view all the answers

    Which of the following statements describes the stabilization of orthophosphate released during ATP hydrolysis?

    <p>It is greatly stabilized by resonance hybrids among the oxygen atoms.</p> Signup and view all the answers

    What is the main source of ATP generation in aerobic organisms?

    <p>Oxidative phosphorylation in the mitochondrial matrix.</p> Signup and view all the answers

    How long can the total ATP/ADP pool sustain active tissue before depletion occurs?

    <p>A few seconds.</p> Signup and view all the answers

    What is the result of the strong electrostatic repulsion in ATP molecules?

    <p>It favors the hydrolysis of ATP.</p> Signup and view all the answers

    What signifies that a reaction is considered exergonic?

    <p>The change in free energy (ΔG) is negative.</p> Signup and view all the answers

    What occurs in a biological system when ΔG is positive?

    <p>The reaction can happen only if free energy is gained.</p> Signup and view all the answers

    What does a zero value for ΔG indicate about a reacting system?

    <p>The system is at equilibrium with no net change.</p> Signup and view all the answers

    How can biochemical reactions be characterized when ΔH is approximately equal to ΔE?

    <p>They follow the relationship ΔG = ΔH - TΔS.</p> Signup and view all the answers

    What can be inferred if ΔG has great magnitude in a reaction?

    <p>The reaction goes virtually to completion and is essentially irreversible.</p> Signup and view all the answers

    In a coupled reaction involving an exergonic and an endergonic process, what is primarily essential for the endergonic reaction to proceed?

    <p>The availability of free energy released from the exergonic reaction.</p> Signup and view all the answers

    Which statement accurately differentiates between exergonic and endergonic processes?

    <p>Exergonic releases energy, whereas endergonic captures energy.</p> Signup and view all the answers

    What defines the stability of a biochemical system when ΔG is greatly positive?

    <p>The system is stable with minimal tendency for a reaction.</p> Signup and view all the answers

    Which compound serves as the primary energy currency in a cell?

    <p>Adenosine triphosphate (ATP)</p> Signup and view all the answers

    What distinguishes ATP from ADP in terms of phosphate groups?

    <p>ATP contains three phosphate groups.</p> Signup and view all the answers

    Which statement accurately describes the energy profile of ATP hydrolysis?

    <p>ATP hydrolysis results in lower energy end products.</p> Signup and view all the answers

    Which of the following compounds has a high group transfer potential?

    <p>Adenosine triphosphate (ATP)</p> Signup and view all the answers

    What is one function of ADP in cellular metabolism?

    <p>ADP can accept phosphate groups to regenerate ATP.</p> Signup and view all the answers

    Which compound is produced during the hydrolysis of ATP to ADP?

    <p>Inorganic phosphate (Pi)</p> Signup and view all the answers

    What type of reaction does ATP hydrolysis represent in cellular processes?

    <p>An exergonic reaction releasing energy</p> Signup and view all the answers

    Which of the following compounds is considered a high-energy intermediate in metabolism?

    <p>Acetyl-CoA</p> Signup and view all the answers

    What is the primary role of phosphates in ATP?

    <p>To store energy in chemical bonds.</p> Signup and view all the answers

    Which of the following statements about ATP and its hydrolysis is incorrect?

    <p>Hydrolysis of ATP results in the formation of AMP.</p> Signup and view all the answers

    Which type of phosphate has a high group transfer potential?

    <p>Anhydride phosphates</p> Signup and view all the answers

    What is the correct relationship between ATP and ADP in terms of energy transfer?

    <p>ATP's hydrolysis releases energy, making ADP and Pi available for biosynthetic reactions.</p> Signup and view all the answers

    Which of the following compounds is categorized as a low-energy phosphate?

    <p>Adenosine monophosphate (AMP)</p> Signup and view all the answers

    What distinguishes a high-energy phosphate from a low-energy phosphate?

    <p>Low-energy phosphates have a less favorable G0' value compared to high-energy phosphates.</p> Signup and view all the answers

    In which scenario would ATP be converted to AMP and PPi?

    <p>In reactions requiring a greater energy input than what ATP can provide.</p> Signup and view all the answers

    Which group of compounds is typically considered high-energy carriers?

    <p>Anhydrides and enol phosphates</p> Signup and view all the answers

    What happens to the free energy during the hydrolysis of ATP?

    <p>It is released and can be utilized by other reactions.</p> Signup and view all the answers

    Which of the following processes requires energy from ATP?

    <p>Active transport of ions</p> Signup and view all the answers

    What is the role of the phosphate group in ATP?

    <p>To facilitate the transfer of energy during biochemical reactions.</p> Signup and view all the answers

    Which of the following statements accurately describes the role of ATP in cellular processes?

    <p>ATP functions primarily in the transference of free energy from exergonic to endergonic processes.</p> Signup and view all the answers

    What constitutes the structure of ATP?

    <p>A nucleotide comprised of adenosine, ribose, and three phosphate groups.</p> Signup and view all the answers

    Which compound has a standard free energy of hydrolysis that is more negative than ATP?

    <p>Phosphoenolpyruvate</p> Signup and view all the answers

    How do heterotrophic organisms primarily acquire free energy?

    <p>By coupling metabolism to the breakdown of complex organic molecules.</p> Signup and view all the answers

    What special complex does ATP form during its cellular reactions?

    <p>A complex with Mg2+ ions.</p> Signup and view all the answers

    In the context of glycolysis, what is the importance of phosphates?

    <p>They are critical in the phosphorylation of intermediates.</p> Signup and view all the answers

    Which term best defines the metabolic processes that utilize phosphates in energy transfer?

    <p>Intermediary metabolism</p> Signup and view all the answers

    What type of organisms primarily rely on ATP as a source of energy?

    <p>All forms of life, including autotrophs and heterotrophs</p> Signup and view all the answers

    What is the role of inorganic phosphate (Pi) in metabolic pathways?

    <p>It participates in energy transfer as part of biochemical transformations.</p> Signup and view all the answers

    Which of the following accurately describes the energy yield from the hydrolysis of ATP compared to other organophosphates?

    <p>ATP hydrolysis releases energy effectively but not as much as some other organophosphates.</p> Signup and view all the answers

    Match the following types of phosphates with their energy transfer potential:

    <p>Low-energy phosphates = Ester phosphates High-energy phosphates = Anhydrides ATP = High group transfer potential AMP = Low group transfer potential</p> Signup and view all the answers

    Match each compound with its role in ATP metabolism:

    <p>ATP = High-energy carrier ADP = Low-energy state Pi = Released during hydrolysis PPi = Product of ATP breakdown</p> Signup and view all the answers

    Match the following enzymes with their functions in energy metabolism:

    <p>Adenylyl kinase = Converts AMP to ADP Inorganic pyrophosphatase = Hydrolyzes PPi Creatine kinase = Transfers phosphate from creatine Phosphofructokinase = Regulates glycolysis</p> Signup and view all the answers

    Match the following reactions with their type:

    <p>ATP to ADP + Pi = Exergonic reaction ADP + Pi to ATP = Endergonic reaction Glycolysis = Energy-producing pathway Citric Acid Cycle = Energy-releasing pathway</p> Signup and view all the answers

    Match the following phosphate molecules with their examples:

    <p>Anhydrides = 1,3-Bisphosphoglycerate Enol phosphates = Phosphoenolpyruvate Phosphoguanidines = Creatine phosphate Ester phosphates = Glycerol phosphate</p> Signup and view all the answers

    Match the following processes with their descriptions:

    <p>Glycolysis = Conversion of glucose to pyruvate with net ATP production Citric Acid Cycle = Releases energy by oxidizing acetyl-CoA Adenylyl Kinase Reaction = Interconverts ATP and ADP Phosphagen System = Utilizes creatine phosphate for quick ATP regeneration</p> Signup and view all the answers

    Match the following enzymes with their functions:

    <p>Hexokinase = Phosphorylation of glucose to glucose-6-phosphate Phosphoglycerate Kinase = Generation of ATP from ADP during glycolysis Pyruvate Kinase = Catalyzes the final step of glycolysis to form pyruvate Succinate Thiokinase = Generates ATP directly in the citric acid cycle</p> Signup and view all the answers

    Match the following compounds with their roles:

    <p>ATP = Primary energy currency of the cell ADP = Intermediary that accepts a phosphate to regenerate ATP Creatine Phosphate = Energy store in muscle cells for rapid ATP production Glycerol-3-Phosphate = Intermediate in glycerol phosphorylation</p> Signup and view all the answers

    Match the following metabolic pathways with their outcomes:

    <p>Glycolysis = Produces two molecules of pyruvate and two ATP Citric Acid Cycle = Generates NADH, FADH2, and GTP/ATP ATP Hydrolysis = Releases energy for cellular work Adenylyl Kinase Activity = Maintains energy homeostasis in cells</p> Signup and view all the answers

    Match the following terms related to metabolic energy processes:

    <p>Exergonic Reaction = Releases free energy, often in ATP catabolism Endergonic Reaction = Requires free energy input, such as in ATP synthesis Phosphate Donor = Molecule that transfers a phosphate group to another compound Activation Energy = Initial energy input required to start a reaction</p> Signup and view all the answers

    Study Notes

    Free Energy in Biochemical Reactions

    • The relationship between free-energy change (ΔG), enthalpy (ΔH), entropy (ΔS), and temperature (T) is expressed by the equation: ∆G = ∆H −T∆S.
    • A negative ΔG indicates an exergonic reaction, which proceeds spontaneously with a loss of free energy.
    • A positive ΔG indicates an endergonic reaction, which requires free energy to proceed.
    • A ΔG of zero signifies equilibrium, with no net change occurring.
    • The standard free-energy change (ΔG0′) is measured when reactants are at 1.0 mol/L and pH is 7.0.
    • ΔG0′ can be calculated from the equilibrium constant (Keq): ∆G 0′ = −RT ln Keq
    • Enzymes accelerate the attainment of equilibrium but do not change the final concentrations of reactants at equilibrium.
    • Exergonic and endergonic reactions in biological systems can be coupled, with the overall net change being exergonic.
    • Catabolism refers to the breakdown or oxidation of fuel molecules, while anabolism refers to synthetic processes that build up substances.
    • Metabolism encompasses both catabolic and anabolic processes.

    ATP and Energy Transfer

    • ATP (adenosine triphosphate) plays a central role in transferring free energy from exergonic to endergonic processes.
    • ATP consists of adenosine (adenine linked to ribose) and three phosphate groups.
    • The hydrolysis of ATP is strongly exergonic due to electrostatic repulsion between negatively charged oxygen atoms in the adjacent phosphate groups and the stabilization of the orthophosphate product.
    • ATP hydrolysis releases energy, which can be used to drive various cellular processes.

    Sources of Free Energy

    • Oxidative phosphorylation is the major source of free energy in aerobic organisms, generating ATP in the mitochondrial matrix.
    • Substrate-level phosphorylation generates ATP directly from a high-energy molecule by transferring its phosphate group to ADP.
    • Photophosphorylation, as seen in photosynthesis, uses light energy to generate ATP.

    Regulation of ATP Levels

    • ATP levels in cells are tightly regulated to ensure a constant supply of energy for cellular activities.
    • When ATP levels decrease, ADP and AMP concentrations increase, acting as metabolic signals to stimulate catabolic pathways and ATP production.
    • ATP can also be hydrolyzed directly to AMP and inorganic pyrophosphate (PPi), releasing free energy.
    • Activation via PPi, often seen in fatty acid activation, is aided by the hydrolysis of PPi to two inorganic phosphates, catalyzed by inorganic pyrophosphatase.
    • The hydrolysis of PPi is exergonic, contributing to the driving force of activation reactions.

    Other Energy Carriers

    • GTP, CTP, and UTP are other triphosphate molecules involved in phosphorylation reactions.
    • Specific nucleoside monophosphate (NMP) kinases catalyze the formation of NDP from the corresponding monophosphates.

    Free Energy Change

    • The relationship between free-energy change (ΔG) and entropy change (ΔS) under constant temperature and pressure is expressed by the equation: ΔG = ΔH −TΔS
    • ΔH represents the enthalpy change (heat), and T is the absolute temperature.
    • A negative ΔG indicates a spontaneous reaction with free energy loss (exergonic).
    • A positive ΔG indicates a reaction requiring free energy gain (endergonic).
    • A ΔG of zero signifies equilibrium with no net change.

    High-Energy Phosphates

    • ATP (Adenosine Triphosphate) is the principal high-energy intermediate in the cell.
    • The hydrolysis of ATP to ADP releases significant free energy, making it the energy currency of the cell.
    • ~P indicates the high-energy phosphate group.

    Energy Capture & Transfer

    • Living organisms obtain energy from their environment through exergonic (energy releasing) processes.
    • Autotrophs utilize simple exergonic processes like sunlight (green plants) or Fe2+ → Fe3+ reactions (some bacteria).
    • Heterotrophs obtain energy by breaking down organic molecules.
    • ATP plays a crucial role in transferring free energy from exergonic to endergonic processes.
    • ATP consists of adenosine (adenine linked to ribose) and three phosphate groups.

    High-Energy Phosphates & ATP

    • The high group transfer potential of ATP allows it to donate phosphate groups to other compounds.
    • ADP can accept phosphate groups to form ATP.
    • The ATP/ADP cycle connects energy-generating processes to energy-utilizing processes.
    • Three major sources of energy capture are:
      • Oxidative phosphorylation (in aerobic organisms)
      • Photosynthesis (in plants)
      • Substrate-level phosphorylation (in some metabolic pathways)
    • The hydrolysis of ATP to ADP releases a significant amount of energy due to the electrostatic repulsion between the negatively charged phosphate groups and the stabilization of the orthophosphate product by resonance.

    Role of ATP in Cellular Processes

    • ATP plays a pivotal role in various cellular processes like biosynthesis, muscular contraction, nerve excitation, and active transport.
    • The ATP/ADP pool is small and replenished rapidly.
    • The high group transfer potential of ATP makes it a versatile energy donor and acceptor.
    • Other high-energy compounds besides ATP include thiol esters, acyl carrier protein, and S-adenosylmethionine.

    Bioenergetics - The role of ATP

    • Bioenergetics is the study of energy changes during biochemical reactions
    • The first law of thermodynamics states that energy cannot be created or destroyed, only transferred or transformed
    • The second law of thermodynamics states that the total entropy of an isolated system can only increase over time
    • Gibbs change in free energy (ΔG) is the energy available to do work in a system
    • Biological systems are essentially isothermal - meaning they occur at a constant temperature
    • Endergonic reactions require energy input to occur
    • Exergonic reactions release energy
    • Coupling of exergonic and endergonic reactions is essential for life - an exergonic reaction can provide the energy for an endergonic reaction
    • The high-energy phosphate bonds in ATP are a readily available source of energy for the cell
    • ATP is hydrolyzed to ADP and inorganic phosphate (Pi) - this reaction releases energy
    • The free energy change of ATP hydrolysis is -30.5 kJ/mol
    • ATP is the "energy currency" of the cell because it can be used to drive many endergonic reactions
    • There are three major sources of ATP: oxidative phosphorylation, substrate-level phosphorylation and photophosphorylation
    • Oxidative phosphorylation is the major source of ATP in aerobic organisms (see Chapter 13)
    • Substrate-level phosphorylation generates ATP directly from the breakdown of high-energy molecules (see Chapter 14)
    • Photophosphorylation is the process by which plants generate ATP using light energy (see Chapter 18)
    • The concentration of ATP and ADP play a role in metabolic regulation - when ATP is depleted, AMP increases, which signals the cell to increase the rate of catabolic reactions (see Chapter 14)
    • The hydrolysis of ATP to AMP and inorganic pyrophosphate (PPi) releases a large amount of energy - this process is important for the activation of long-chain fatty acids (see Chapter 22)
    • Inorganic pyrophosphatase hydrolyzes PPi - which ensures that the activation reaction goes to completion
    • Other nucleotide triphosphates, such as GTP, CTP, and UTP, also have high group transfer potential and can be used to drive reactions in the cell.

    Group Transfer Potential and Biologically Important Phosphates

    • Group transfer potential refers to the tendency of a phosphate group to be transferred to an acceptor molecule
    • The free energy change of hydrolysis (ΔG0′) of a phosphate compound is a measure of its group transfer potential
    • High-energy phosphate compounds have a large negative ΔG0′ of hydrolysis - this means that the reaction is favorable and will release energy
    • The intermediate position of ATP in terms of group transfer potential makes it an ideal energy carrier
    • Other important biologically important phosphate compounds include: creatine phosphate, phosphoenolpyruvate, glucose-6-phosphate, 1,3-bisphosphoglycerate, and acetyl-CoA
    • Creatine phosphate has higher group transfer potential than ATP and functions as a short-term energy store in muscle tissue
    • Phosphoenolpyruvate is a high-energy compound that is important in glycolysis (see Chapter 14)
    • Glucose-6-phosphate is an intermediate in glycolysis and is also important in glycogen metabolism (see Chapter 19)
    • 1,3-bisphosphoglycerate is an intermediate in glycolysis (see Chapter 14)
    • Acetyl-CoA is a high-energy compound that is involved in the citric acid cycle (see Chapter 15)
    • The high group transfer potential of ATP enables it to act as a phosphate group donor in many different reactions
    • ADP can act as a phosphate group acceptor - forming ATP from high-energy compounds with a greater group transfer potential
    • ATP/ADP cycle is the energy currency of the cell - ATP is used to drive endergonic reactions and is continuously replenished by exergonic reactions

    High-Energy Phosphates

    • High-energy phosphates play a key role in capturing and transferring energy in biological systems.
    • They are compounds with a high group transfer potential, meaning they readily release energy when their phosphate group is transferred to an acceptor molecule.
    • This energy release drives various cellular processes like biosynthesis, muscle contraction, nerve signaling, and active transport.

    Adenosine Triphosphate (ATP)

    • ATP is the primary high-energy intermediate in living cells.
    • The symbol ~P indicates the phosphate group attached to the bond has a high group transfer potential.
    • ATP can transfer its energy to other molecules through a series of reactions, serving as a "currency" of energy within the cell.

    The Importance of Low-Energy Phosphates

    • Low-energy phosphates are essential for maintaining energy balance within the cell.
    • They have lower group transfer potential than ATP and are crucial for:
      • Activating reactions that require ATP.
      • Rephosphorylating AMP back to ADP.
      • Releasing energy from the terminal phosphate of ATP when it is converted to ADP and Pi.

    Adenylyl Kinase

    • Adenylyl Kinase, also known as Myokinase, is present in various cells and plays a crucial role in maintaining energy homeostasis.
    • It interconverts adenine nucleotides by catalyzing the following reaction:
      • ADP + ADP ↔ ATP + AMP
    • Adenylyl Kinase helps in:
      • Utilizing the group transfer potential of ADP to synthesize ATP.
      • Rephosphorylating AMP formed during ATP-dependent activation reactions.
      • Ensuring the terminal phosphate of ATP is hydrolyzed to ADP and Pi.

    Phosphagens

    • Phosphagens act as energy storage molecules.
    • Examples include creatine phosphate (found in vertebrates) and arginine phosphate (found in invertebrates).
    • During rapid ATP utilization (e.g., muscle contraction), Phosphagens maintain ATP concentration.
    • When the ATP/ADP ratio is high, their concentration increases and acts as an energy reserve.

    Phosphate Cycles and Nucleotide Interchange

    • Phosphate cycles and adenine nucleotide interchange ensure efficient energy utilization and conservation.
    • ADP can be recycled to ATP via several reactions, including:
      • Glycolysis
      • Citric acid cycle
    • Other nucleoside triphosphates like UTP, GTP, and CTP are synthesized from their diphosphates using nucleoside diphosphate (NDP) kinases.

    Studying That Suits You

    Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

    Quiz Team

    Related Documents

    Harper's Biochemistry Chapter 11 - Bioenergetics.PDF
    Harper's Biochemistry Chapter 11 - Bioenergetics PDF

    Description

    Test your knowledge on the concepts of free energy in biochemical reactions. This quiz covers key equations and terminology related to exergonic and endergonic reactions, as well as their implications in biological systems. Explore how free energy relates to enzyme activity and metabolic processes.

    More Like This

    Use Quizgecko on...
    Browser
    Open
    Browser
    Browser