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Catabolism:
breakdown of complex molecules into smaller ones
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Anabolism
reactions that build cells
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Gibbs free energy change, ∆G.
The direction of a reaction can be predicted by a thermodynamic quantity called Gibbs free energy change, ∆G.
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∆H:
Change in enthalpy, the heat energy absorbed or released
∆H-driven reactions release heat.
∆S-driven reactions depend on temperature.
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T∆S
- Product of temperature and entropy change
- -If ∆G< 0, the process may go forward.
- -If ∆G> 0, the reaction will go in reverse.
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Intrinsic properties of a reaction
The changes of ΔHand ΔS contributing to ΔG
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energy carriers
Molecules that gain or release small amounts of energy in reversible reactions
Examples: NADH and ATP
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Electron donor:
reducing agent
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Electron acceptor
an oxidizing agent
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Adenosine triphosphate
contains a base, sugar, and three phosphates
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ATP can transfer energy to cell processes in three different ways:
- 1.Hydrolysis-releasing phosphate (Pi)
- 2.Hydrolysis-releasing pyrophosphate (PPi)
- 3.Phosphorylation of an organic molecule
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Nicotinamideadenine dinucleotide(NADH)
- carries two or three times as much energy as ATP.
- -It also donates and accepts electrons.
- -NADH is the reduced form.
- -NAD+is the oxidized form.
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Flavine adenine dinucleotide
- is another related coenzyme that can transfer electrons
- Unlike NAD+, FAD is reduced by two electronsand two protons
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Fermentation
partial breakdown of organic food without net electron transfer to an inorganic terminal electron acceptor
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Respiration:
complete breakdown of organic molecules with electron transfer to a terminal electron acceptor such as O2
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Photoheterotrophy:
catabolism is conducted with a “boost” from light
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