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Questions and Answers
Bioenergetics focuses on energy flow and transformation within non-living systems.
Bioenergetics focuses on energy flow and transformation within non-living systems.
False
The First Law of Thermodynamics states that energy can be created or destroyed.
The First Law of Thermodynamics states that energy can be created or destroyed.
False
In biological systems, energy transformations can be completely efficient with no loss of energy.
In biological systems, energy transformations can be completely efficient with no loss of energy.
False
A reaction is considered exergonic if the change in free energy (ΔG) is greater than zero.
A reaction is considered exergonic if the change in free energy (ΔG) is greater than zero.
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Free energy is a measure of the potential work obtainable from a system under constant temperature and pressure.
Free energy is a measure of the potential work obtainable from a system under constant temperature and pressure.
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The change in free energy during a chemical reaction can be calculated using the equation ΔG = ΔH - TΔS.
The change in free energy during a chemical reaction can be calculated using the equation ΔG = ΔH - TΔS.
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Energy-rich compounds like ATP play no significant role in metabolism.
Energy-rich compounds like ATP play no significant role in metabolism.
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Entropy in biological systems always decreases as energy is transformed.
Entropy in biological systems always decreases as energy is transformed.
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A positive ΔG indicates that the reaction is exergonic and requires no energy input.
A positive ΔG indicates that the reaction is exergonic and requires no energy input.
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ATP is composed of adenine, ribose, and two phosphate groups.
ATP is composed of adenine, ribose, and two phosphate groups.
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The standard free energy change (ΔG°) can predict the spontaneity of a reaction under standard conditions.
The standard free energy change (ΔG°) can predict the spontaneity of a reaction under standard conditions.
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Creatine phosphate is primarily found in brain cells.
Creatine phosphate is primarily found in brain cells.
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NADH and FADH2 are involved in the electron transport chain during oxidative phosphorylation.
NADH and FADH2 are involved in the electron transport chain during oxidative phosphorylation.
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In oxidation-reduction reactions, oxidation involves the gain of electrons.
In oxidation-reduction reactions, oxidation involves the gain of electrons.
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Hydrolysis of ATP releases energy by breaking the bond between the first and second phosphate group.
Hydrolysis of ATP releases energy by breaking the bond between the first and second phosphate group.
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A reaction with ΔG° of -30 kJ/mol is spontaneous at standard conditions.
A reaction with ΔG° of -30 kJ/mol is spontaneous at standard conditions.
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ATP coupling involves connecting two endergonic reactions together.
ATP coupling involves connecting two endergonic reactions together.
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The gas constant (R) is generally valued at 8.314 J/mol·K.
The gas constant (R) is generally valued at 8.314 J/mol·K.
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During cellular respiration, glucose is oxidized and oxygen is reduced.
During cellular respiration, glucose is oxidized and oxygen is reduced.
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The equation for standard free energy change includes the natural logarithm of the equilibrium constant.
The equation for standard free energy change includes the natural logarithm of the equilibrium constant.
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The process of active transport requires ATP to move substances down their concentration gradient.
The process of active transport requires ATP to move substances down their concentration gradient.
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Study Notes
Bioenergetics Overview
- Bioenergetics studies energy flow and transformations in living organisms, crucial for structure, metabolism, and reproduction.
- Energy transformations follow thermodynamic principles of free energy and energy exchange.
Basic Thermodynamic Principles
- First Law of Thermodynamics: Energy cannot be created or destroyed, only converted. Biological systems convert chemical food energy into work, heat, or stored energy (ATP).
- Second Law of Thermodynamics: Energy conversions release some energy as unusable heat, increasing system disorder (entropy). Life processes are inherently inefficient due to heat production.
Free Energy (Gibbs Free Energy)
- Free energy (ΔG): Represents the amount of usable energy in a system at constant temperature and pressure.
- ΔG equation: ΔG = ΔH - TΔS (where ΔH is change in enthalpy, T is temperature in Kelvin, and ΔS is change in entropy).
- Significance of ΔG: A negative ΔG indicates an exergonic (energy-releasing) reaction that proceeds spontaneously. A positive ΔG indicates an endergonic (energy-requiring) reaction requiring external energy. A ΔG of zero means the system is at equilibrium.
Standard Free Energy Change (ΔG°)
- Standard conditions: Reactions are measured at 1 M reactant concentrations, 1 atm pressure, and 25°C.
- ΔG° and equilibrium constant (K): ΔG° = -RTlnK (where R is the gas constant and T is temperature). This relates standard free energy change to reaction spontaneity.
Energy-Rich Compounds
- Energy-rich compounds: Store substantial energy in their bonds for cellular work.
- Adenosine Triphosphate (ATP): The primary energy currency of the cell, comprising adenine, ribose, and three phosphate groups.
- ATP Hydrolysis Reaction: ATP + H₂O → ADP + Pi + energy (where ADP is adenosine diphosphate and Pi is inorganic phosphate.) This releases energy from the high-energy bond between phosphate groups, usable for cellular processes.
- ATP Regeneration: Cells regenerate ATP through processes like cellular respiration and photosynthesis. This constant cycling is essential for metabolism.
- Other Energy-Rich Compounds: -Creatine phosphate: Quickly regenerates ATP in muscle cells. -NADH and FADH₂: Electron carriers involved in energy transfer during oxidative phosphorylation.
ATP in Energy Exchange
- ATP Coupling: ATP is often used to couple exergonic reactions (energy-releasing) with endergonic (energy-requiring) reactions to efficiently utilize released energy.
- Examples of ATP Usage: -Macromolecule synthesis (proteins, nucleic acids, polysaccharides) -Active transport (moving ions against concentration gradients) -Muscle contraction (actin and myosin filament movement)
Oxidation-Reduction (Redox) Reactions
- Redox reactions: Fundamental to energy metabolism, involving electron transfer.
- Oxidation: Loss of electrons (or hydrogen atoms), often accompanied by energy loss or increase in positive charge.
- Reduction: Gain of electrons (or hydrogen atoms), often accompanied by energy gain or decrease in positive charge.
- Redox Examples in Metabolism: -Cellular respiration: Glucose is oxidized, oxygen is reduced. -NAD⁺/NADH and FAD/FADH₂ are key electron carriers in cellular redox reactions.
Simple Calculations
- Calculating ΔG: Using the given ΔG° or K, and temperature to calculate the free energy change for any reaction.
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Description
This quiz explores the fundamental concepts of bioenergetics, focusing on energy flow and transformations in living organisms. It covers key thermodynamic principles, including the First and Second Laws of Thermodynamics, and the significance of Gibbs Free Energy. Test your understanding of these crucial topics in biological energy systems.
