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Questions and Answers
What type of energy source involves capturing energy through light absorption?
What type of energy source involves capturing energy through light absorption?
Which process involves electrons from inorganic compounds?
Which process involves electrons from inorganic compounds?
What thermodynamic quantity predicts the direction of a reaction?
What thermodynamic quantity predicts the direction of a reaction?
In which process are electrons derived from organic compounds?
In which process are electrons derived from organic compounds?
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What process involves the decrease in entropy and the assembly of simple molecules into complex cell components?
What process involves the decrease in entropy and the assembly of simple molecules into complex cell components?
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What formula represents the calculation of Gibbs free energy change?
What formula represents the calculation of Gibbs free energy change?
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In which type of reaction does heat exit the system, resulting in a decrease in total energy?
In which type of reaction does heat exit the system, resulting in a decrease in total energy?
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What is the ultimate fate of most of the energy dissipated through the total metabolism of all life-forms?
What is the ultimate fate of most of the energy dissipated through the total metabolism of all life-forms?
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Which prefix indicates that CO2 is fixed and assembled into organic molecules as a carbon source for biomass?
Which prefix indicates that CO2 is fixed and assembled into organic molecules as a carbon source for biomass?
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Which prefix refers to the process where chemical reactions yield energy without absorbing light?
Which prefix refers to the process where chemical reactions yield energy without absorbing light?
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Which molecule carries two or three times as much energy as ATP?
Which molecule carries two or three times as much energy as ATP?
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What is the oxidized form of nicotinamide adenine dinucleotide (NADH)?
What is the oxidized form of nicotinamide adenine dinucleotide (NADH)?
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In the equation NAD+ + 2 H+ + 2 e– → NADH + H+, how many hydrogen atoms are consumed in the reduction of NAD+?
In the equation NAD+ + 2 H+ + 2 e– → NADH + H+, how many hydrogen atoms are consumed in the reduction of NAD+?
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Why do lipid catabolism reactions require more electron accepting energy carriers compared to glucose?
Why do lipid catabolism reactions require more electron accepting energy carriers compared to glucose?
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Why do different kinds of reactions use different energy carriers according to the text?
Why do different kinds of reactions use different energy carriers according to the text?
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What is the Gibbs free energy change (∆G) for the reaction 2H2 + O2 -> 2H2O, given that the enthalpy change (∆H) is -572 kJ/mol and the entropy change (∆S) is -0.327 kJ/(mol-K)?
What is the Gibbs free energy change (∆G) for the reaction 2H2 + O2 -> 2H2O, given that the enthalpy change (∆H) is -572 kJ/mol and the entropy change (∆S) is -0.327 kJ/(mol-K)?
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Which factor plays a crucial role in determining the Gibbs free energy (∆G) of a reaction?
Which factor plays a crucial role in determining the Gibbs free energy (∆G) of a reaction?
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If a reaction has a negative ∆G value under standard conditions, what does this indicate about the reaction?
If a reaction has a negative ∆G value under standard conditions, what does this indicate about the reaction?
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What happens to the Gibbs free energy (∆G) of a reaction as temperature increases?
What happens to the Gibbs free energy (∆G) of a reaction as temperature increases?
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In the context of energy carriers and electron transfer, what role do many of the cell's energy transfer reactions involve?
In the context of energy carriers and electron transfer, what role do many of the cell's energy transfer reactions involve?
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What is the purpose of ATP in cells?
What is the purpose of ATP in cells?
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Which molecule is considered an energy carrier and can transfer electrons?
Which molecule is considered an energy carrier and can transfer electrons?
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Under physiological conditions, ATP forms a complex with which essential nutrient for cells?
Under physiological conditions, ATP forms a complex with which essential nutrient for cells?
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What are the components that make up adenosine triphosphate (ATP)?
What are the components that make up adenosine triphosphate (ATP)?
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How does ATP transfer energy to cell processes?
How does ATP transfer energy to cell processes?
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Study Notes
Energy and Metabolism
- Cells use energy to assemble simple, disordered molecules into complex, ordered forms such as cell components, which is known as anabolism (decrease in entropy).
- This process requires energy, and the measurement of energy in a system is called enthalpy (ΔH).
- Exothermic reactions release heat, resulting in a decrease in total energy (negative ΔH).
- Microbes use energy to build order, and this requires a continual gain of energy and continual radiation of heat.
Important Prefixes
- Auto-: CO2 is fixed and assembled into organic molecules (carbon source).
- Hetero-: Preformed organic molecules are acquired and assembled into new organic molecules (carbon source).
- Photo-: Light absorption captures energy (energy source).
- Chemo-: Chemical reactions yield energy without absorbing light (energy source).
- Litho-: Inorganic molecules donate electrons (electron source).
- Organo-: Organic molecules donate electrons (electron source).
Energy Sources
- Chemotrophy yields energy from electron transfer between chemicals.
- Chemoorganotrophy: electrons from organic compounds.
- Chemolithotrophy: electrons from inorganic compounds.
- Phototrophy yields energy from light absorption.
- Photoautotrophy: absorption with CO2 fixation.
- Photoheterotrophy: absorption without CO2 fixation.
Gibbs Free Energy Change
- The direction of a reaction can be predicted by the Gibbs free energy change (ΔG).
- ΔG = ΔH – TΔS, where ΔH is the change in enthalpy and ΔS is the change in entropy.
- A negative ΔG value indicates a spontaneous reaction.
Gibbs Free Energy Example
- Reaction: 2H2 + O2 -> 2H2O
- ΔH is -572 kJ/mol (stable bonds of H2O are formed, and heat is released).
- ΔS is -0.327 kJ/(mol-K) (entropy decreases).
Energy Carriers and Electron Transfer
- Energy carriers are molecules that gain or release small amounts of energy in reversible reactions.
- Examples: NADH and ATP.
- NADH can transfer electrons and carry energy.
- ATP is an ancient component of cells, found in all living organisms.
ATP Structure and Function
- ATP consists of a base (adenine), a sugar (ribose), and three phosphates.
- ATP is an energy carrier that can release energy by hydrolysis or phosphorylation of an organic molecule.
- ATP always forms a complex with Mg2+ under physiological conditions.
NADH and FADH
- NADH carries energy and electrons, donating and accepting electrons.
- NAD+ is the oxidized form, and NADH is the reduced form.
- FADH2 is another coenzyme that can transfer electrons, with FAD being the oxidized form.
Why Different Energy Carriers?
- Different reactions use different energy carriers due to varying redox levels and energy yields.
- Different energy carriers are used to be efficient and not wasteful.
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Description
Learn how to calculate the change in Gibbs free energy (ΔG) using the equation ΔG = ΔH - TΔS with an example reaction involving the formation of water from hydrogen and oxygen. Understand the concept of bond stability, heat release, and entropy change in relation to ΔG calculations.
