BIOC*4520: Metabolic Processes lec 3
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What does the Gibbs equation ΔG = ΔH - TΔS represent in metabolic processes?

It represents the relationship between free energy change (ΔG), enthalpy change (ΔH), and entropy change (TΔS), determining the spontaneity of chemical reactions.

How are organisms classified according to their cellular organization?

Organisms are classified into six kingdoms based on their cellular organization: Archaea and Bacteria are unicellular prokaryotes, while the other 4 are eukaryotes Protista: unicellular Fungi: uni- or multicellular Plantae, and Animalia are eukaryotes are multicellular.

What indicates a favorable reaction in terms of Gibbs free energy?

A favorable reaction is indicated if the change in Gibbs free energy (ΔGo) is negative, meaning the free energy of the products is less than that of the reactants.

What can be inferred when the equilibrium constant (K'eq) is greater than 1.0?

<p>If K'eq is greater than 1.0, it implies that ΔG˚ is negative and the reaction proceeds forward, favoring product formation.</p> Signup and view all the answers

What is the significance of ΔG° under standard conditions?

<p>ΔG° measures the free energy change of a reaction under standard conditions, Understanding ΔG° is crucial for predicting how reactions will behave in a biological context.</p> Signup and view all the answers

Eukaryotes primarily use ______ respiration, which is more energy-efficient.

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

Eukaryotes store energy in the form of ______ in animals and starch in plants.

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

One reason eukaryotes have greater energy efficiency is their ______ of cellular structures.

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

High energy efficiency in eukaryotes supports complex ______ structures and functions.

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

whats the formula for Keq

<p>Keq=[product]/[reactant] if the rxn eqn is aA+bB-&gt;cC+dD , then Keq=[C]^c x [D]^d / [A]^a x [B]^b</p> Signup and view all the answers

Which of the following best describes the standard state for liquid substances?

<p>As pure substance at 1 M concentration.</p> Signup and view all the answers

How is ΔG° calculated using temperature and entropy?

<p>ΔG° = ΔH° - TΔS°</p> Signup and view all the answers

What does the equation ΔG° = -RT ln(K) illustrate at equilibrium?

<p>The connection between ΔG° and the equilibrium constant K.</p> Signup and view all the answers

What units are used to express ΔG°?

<p>Kilojoules per mole (kJ/mol)</p> Signup and view all the answers

How is ΔG° calculated using the equilibrium constant K?

<p>ΔG° = -RTlnK</p> Signup and view all the answers

when ΔG° is 0, what value is the equilibrium constant K and what happens to the rxn

<p>The K value is =1 and the rxn is in equilibrium</p> Signup and view all the answers

when ΔG° is +ve, what value is the equilibrium constant K and what happens to the rxn

<p>the K values is less than 1, the rxn favours the reactants</p> Signup and view all the answers

when ΔG° is -ve, what value is the equilibrium constant K and what happens to the rxn

<p>the k value is +1, and the reaction moves in the forward direction towards the products</p> Signup and view all the answers

What are the three factors that determine the free-energy change of a reaction in vivo?

<p>The standard change in free energy, actual concentrations of products and reactants, and temperature.</p> Signup and view all the answers

How does the actual concentration of reactants and products affect the free energy change in a reaction?

<p>High concentrations of products or low concentrations of reactants can lead to a more positive ΔG, making a reaction less favorable.</p> Signup and view all the answers

Explain how temperature influences the free energy change in cellular reactions.

<p>Temperature affects the kinetic energy of molecules, influencing reaction rates and thus altering the free energy available for reactions.</p> Signup and view all the answers

Why are hydrolytic reactions considered strongly favorable? (addition of water)

<p>Hydrolytic reactions are considered strongly favorable because they tend to be spontaneous, releasing energy that drives other biochemical processes.</p> Signup and view all the answers

How do chemotrophs obtain energy through the oxidation of reduced compounds?

<p>Chemotrophs obtain energy by the complete oxidation of reduced compounds, which is a thermodynamically favorable process that releases energy.</p> Signup and view all the answers

What does it mean for a reaction to be thermodynamically favorable but kinetically slow?

<p>A reaction can be thermodynamically favorable, meaning it has a negative ΔG, yet be kinetically slow if it has high activation energy barriers that inhibit the reaction rate.</p> Signup and view all the answers

standard free energy changes are additive

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

why do Isomerization reactions have smaller free-energy changes:

<p>This is because the reactants and products are chemically very similar—just arranged differently. therefore the energy difference between them is much smaller than Hydrolytic reactions (where bonds are broken)</p> Signup and view all the answers

why is the energy difference between these two enantiomers essentially zero, or very close to zero?

<p>When one enantiomer (e.g., D-glucose) is converted into its mirror image (e.g., L-glucose), the chemical composition remains exactly the same.</p> Signup and view all the answers

What method do chemotrophs primarily use to obtain energy?

<p>Oxidation of reduced compounds</p> Signup and view all the answers

Why is the oxidation of reduced fuels with O2 considered stepwise and controlled in biochemistry?

<p>It facilitates energy conservation by releasing it gradually.</p> Signup and view all the answers

What happens during the complete oxidation of reduced compounds?

<p>The reaction occurs spontaneously and liberates energy.</p> Signup and view all the answers

What is the primary benefit of a stepwise oxidation of food in living organisms?

<p>It reduces the risk of energy loss as heat.</p> Signup and view all the answers

How does the process of chemotrophy compare to photosynthesis?

<p>Chemotrophy relies on chemical reactions, while photosynthesis relies on light reactions.</p> Signup and view all the answers

What happens during the hydrolysis of ATP that releases energy?

<p>ATP breaks down into ADP and inorganic phosphate (Pi), resulting in better charge separation and increased stability of the products.</p> Signup and view all the answers

How does solvation play a role in the favorability of ATP hydrolysis?

<p>The products ADP and Pi are better surrounded by water than ATP, which makes the hydrolysis process more favorable.</p> Signup and view all the answers

In what way does resonance stabilization contribute to ATP hydrolysis?

<p>Resonance stabilization allows the products ADP and Pi to share energy more easily, increasing their stability compared to ATP.</p> Signup and view all the answers

What are the implications of breaking down ATP for energy in biological systems?

<p>The breakdown of ATP releases a significant amount of energy, driving various biological processes efficiently.</p> Signup and view all the answers

when ATP gives/provides energy it can change depending on two things, what are those things (in vivo)

<ul> <li>standard free enrgy</li> <li>the concentration of reactants and products in vivo</li> </ul> Signup and view all the answers

when the body uses ATP, it uses the version coupled with Mg (Mg-ATP), and its the same scenario for when the ATP is broken down

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

Chemical coupling of exergonic and endergonic reactions allows otherwise unfavorable reactions to occur.

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

ATP is not involved in chemical coupling during metabolic reactions.

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

A "high-energy" molecule like ATP reacts directly with the metabolite that requires activation.

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

Exergonic reactions provide the energy needed to drive endergonic reactions in the body.

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

Several phosphorylated compounds release a small amount of energy when they undergo hydrolysis.

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

how does resonance stabilize compounds

<p>After hydrolysis, the products (such as ADP and inorganic phosphate) are stabilized through resonance delocalization. In this context, resonance allows the negative charge, particularly on the phosphate group, to be distributed across multiple oxygen atoms. This delocalization reduces the electron density on any one atom, lowering the overall potential energy of the system.</p> Signup and view all the answers

in what ways does hydrolysis stabilize a compound phosphorylated compound?

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

tautomerization, is a structural rearrangement that leads to an even more stable form

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

Phosphate can be transferred from compounds with higher ΔG’o to those with lower ΔG’o

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

PEP + ADP => Pyruvate + ATP is a nonfavourable rxn

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

how is ATP made a potent source of chemical energy in cells

<p>Cellular ATP concentration is usually far above the equilibrium concentration</p> Signup and view all the answers

what role does P-Cr play in the transfer of energy?

<p>P-Cr plays a key role in transferring energy in muscles. When your muscles need energy fast (like during intense exercise), PCr donates its phosphate group to ADP, turning it into ATP.</p> Signup and view all the answers

Study Notes

Energy and Metabolic Processes

  • Gibbs free energy equation: ΔG = ΔH - TΔS. It describes energy transformations in biological systems.
  • Organisms perform energy transductions to accomplish work necessary for survival.

Six Kingdoms of Life

  • Archaea: Unicellular prokaryotes with distinctive biochemistry and genetics.
  • Bacteria: Unicellular prokaryotes, diverse in forms and functions.
  • Protista: Unicellular eukaryotes, often found in aquatic environments.
  • Fungi: Can be unicellular or multicellular eukaryotes, known for decomposing organic matter.
  • Plantae: Multicellular eukaryotes, primarily photosynthetic organisms.
  • Animalia: Multicellular eukaryotes, heterotrophic and diverse in form and behavior.

Metabolism and Chemical Reactions

  • Metabolism encompasses all chemical reactions within a cell, providing energy and necessary compounds for life.
  • Constant temperature and pressure on Earth allows for a simplified bioenergetic analysis using standard Gibbs free energy (ΔGo).

Gibbs Free Energy and Reaction Favorability

  • A reaction is favorable when ΔGo is negative, indicating products have lower free energy than reactants.
  • Example reaction: A + B ⇄ C + D will proceed if GC + GD < GA + GB.

Equilibrium and Spontaneity

  • ΔG° measures the spontaneity of reactions in biological systems under standard conditions.
  • Standard conditions involve starting with 1 M concentrations of reactants.
  • The gas constant (R) is valued at 0.00831 kJoule/mole/K.

Relationships of Equilibrium Constant and ΔG°

  • At equilibrium (K'eq = 1.0), ΔG° is zero, indicating no net change in concentrations.
  • When K'eq > 1.0, ΔG° is negative, and the reaction proceeds in the forward direction.
  • When K'eq < 1.0, ΔG° is positive, favoring the reverse reaction.

Eukaryotic Organisms

  • Complex cells featuring a nucleus and organelles, including plants, animals, fungi, and protists.

Cellular Respiration

  • Primarily relies on aerobic respiration for higher energy efficiency compared to anaerobic processes.
  • Mitochondria function as the energy powerhouse, producing ATP via oxidative phosphorylation.

ATP Production Mechanisms

  • Glycolysis:
    • Located in the cytoplasm, converts glucose to pyruvate with a yield of 2 ATP.
  • Krebs Cycle:
    • Takes place in mitochondria, processes pyruvate to create electron carriers (NADH, FADH2) and generates 2 ATP.
  • Electron Transport Chain:
    • Situated in the inner mitochondrial membrane, utilizes electron carriers to create up to 34 ATP through chemiosmosis.

Energy Conversion Efficiency

  • Aerobic respiration achieves about 34% efficiency in converting glucose energy into ATP, with excess energy released as heat.
  • Heat production aids in maintaining body temperature for warm-blooded species.

Photosynthesis in Plants

  • Eukaryotic plants convert solar energy to chemical energy using chloroplasts.
  • Comprises two stages: light-dependent reactions (producing ATP and NADPH) and the Calvin cycle (utilizing ATP and NADPH for glucose synthesis).
  • A highly efficient method for energy capture and storage.

Energy Storage Methods

  • Eukaryotes store energy as glycogen (in animals) and starch (in plants).
  • Lipids provide a long-term energy reserve, yielding more energy per gram than carbohydrates.

Adaptations for Energy Efficiency

  • Specialized structures like mitochondria and chloroplasts evolved to enhance energy production efficiency.
  • Allosteric regulation of key enzymes optimizes energy resource utilization.

Eukaryotes vs. Prokaryotes

  • Eukaryotes typically exhibit greater energy efficiency due to compartmentalization and more intricate metabolic pathways relative to prokaryotes.

Implications of Energy Efficiency

  • High energy efficiency enables the support of complex multicellular structures and diverse functions.
  • Influences growth, reproduction, and survival capabilities across a range of environments.

Future Research Directions

  • Investigate energy pathway optimization in eukaryotes for applications in bioengineering and sustainability efforts.
  • Study the contribution of microbiomes to enhancing energy efficiency in eukaryotic organisms.

ΔG° (Standard Gibbs Free Energy Change)

  • ΔG° denotes the change in Gibbs free energy at standard conditions: 1 atm pressure, 1 M concentration, typically at 25°C.
  • The sign of ΔG° determines reaction spontaneity:
    • Negative ΔG° signifies a spontaneous reaction.
    • Positive ΔG° indicates a non-spontaneous reaction.
  • Calculation formula:
    • ΔG° = ΔH° - TΔS°
      • ΔH° represents the change in enthalpy.
      • T is the temperature measured in Kelvin.
      • ΔS° indicates the change in entropy.
  • At equilibrium, the relationship is defined as ΔG° = -RT ln(K):
    • R is the universal gas constant (8.314 J/mol·K).
    • T remains the temperature in Kelvin.
    • K is the equilibrium constant.
  • Standard states provide a framework for measurements:
    • Gases are measured at 1 atm pressure.
    • Pure liquids and solids are evaluated at 1 M concentration.
    • Aqueous solutions are maintained at 1 M concentration.
  • Units of ΔG° are generally expressed in kilojoules per mole (kJ/mol).
  • Applications span across thermodynamics, aiding in predicting the feasibility of reactions and assessing biochemical pathways' favorability.
  • Key characteristics:
    • ΔG° is influenced by temperature and does not indicate the reaction rate—just its thermodynamic favorability.
    • It can be affected by variations in concentration, pressure, and temperature in practical applications.

Free-Energy Change in Cellular Reactions

  • Free-energy change (( \Delta G )) for reactions in a cell is influenced by several factors, making it dynamic rather than standard.
  • Standard change in free energy (( \Delta G^\circ )) is a baseline measurement under idealized conditions, typically at specific temperature and pressure.
  • Actual concentrations of reactants and products in the cell significantly shift the free-energy change, differing from standard conditions.

Reaction Equation

  • For the generalized reaction format: ( aA + bB \rightarrow cC + dD )
  • The equation to calculate the free energy change includes:
    • Standard free energy change: ( \Delta G^\circ )
    • Actual concentrations of reactants and products: expressed as ([A]), ([B]), ([C]), and ([D])
    • The formula: [ \Delta G' = \Delta G^\circ + RT \ln \left( \frac{[C]^c[D]^d}{[A]^a[B]^b} \right) ]
    • ( R ) represents the gas constant, and ( T ) is the temperature in Kelvin.

Implications for Cellular Reactions

  • Conditions within the cell (in vivo) often deviate from standard, affecting energy outcomes of biochemical reactions.
  • This variability is crucial for understanding metabolic pathways and cellular functioning.

Hydrolytic Reactions

  • Hydrolytic reactions are generally spontaneous and strongly favorable.
  • Significant energy release occurs during these reactions, driving various biological processes.

Isomerization Reactions

  • Isomerization reactions involve smaller changes in free energy compared to hydrolytic reactions.
  • Enantiomeric isomerization, such as between D-Glucose and L-Glucose, exhibits a standard free energy change (ΔG°) of 0, indicating equilibrium.

Oxidation of Reduced Compounds

  • Complete oxidation of reduced compounds is highly favorable and is a primary energy source for chemotrophs.
  • In biochemical contexts, oxidation processes occur in a stepwise and controlled manner, particularly when using oxygen (O2).

Thermodynamics vs. Kinetics

  • A reaction being thermodynamically favorable doesn't imply that it will occur quickly; kinetics play a crucial role in reaction rates.

Complete Oxidation of Reduced Compounds

  • Complete oxidation of reduced compounds is a highly favorable process.
  • This means that reactions where substances combine with oxygen to release energy occur spontaneously.
  • This process is essential for chemotrophs to obtain energy.
  • Chemotrophs are organisms that use chemical reactions to obtain energy.
  • Examples of chemotrophs include bacteria and humans.

Controlled Oxidation in Biochemistry

  • In biochemistry, the oxidation of reduced fuels with O2 is a carefully controlled, step-by-step process.
  • This allows for the gradual release of energy, rather than a sudden burst.
  • This controlled process is essential for the efficient utilization of energy by living organisms.

Hydrolysis of ATP

  • ATP hydrolysis is highly favorable under standard conditions.
  • ATP is broken down into ADP and Pi, releasing energy.
  • Products experience better charge separation.
  • ADP and Pi have more favorable resonance stabilization.
  • Products are better solvated (hydrated).

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