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General Biology - Cellular Energy and Metabolism

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Termini in questo insieme (23)

  • First Law of Thermodynamics

    Energy and matter cannot be created or destroyed, only transformed. Organisms use energy from the sun or chemical bonds to perform cellular work.

  • Second Law of Thermodynamics

    In any closed system, entropy tends to increase. Living systems are open systems that use energy to maintain order and decrease internal entropy.

  • Kinetic vs Potential Energy

    Kinetic energy is energy of motion (e.g., thermal energy). Potential energy is stored energy (e.g., chemical energy in bonds).

  • Gibbs Free Energy Equation

    Free energy change is given by \(\Delta G = \Delta H - T\Delta S\), where G is free energy, H is enthalpy, T is temperature, and S is entropy.

  • Exergonic Reactions

    Reactions that release energy, occur spontaneously, and have a negative change in free energy (\(\Delta G < 0\)).

  • Endergonic Reactions

    Reactions that require energy input, are non-spontaneous, and have a positive change in free energy (\(\Delta G > 0\)).

  • Reaction Coupling

    Linking an exergonic reaction to an endergonic one so the overall process is spontaneous (\(\Delta G < 0\)), often via ATP phosphorylation.

  • ATP Structure and Function

    ATP consists of adenine, ribose, and three phosphate groups. Hydrolysis of ATP releases energy used to power cellular work.

  • ATP Hydrolysis

    ATP + H2O → ADP + Pi + energy. The breaking of the terminal phosphate bond releases energy for cellular processes.

  • Types of Cellular Work Powered by ATP

    ATP powers transport work (moving solutes), mechanical work (motor proteins moving vesicles), and chemical work (endergonic reactions).

  • Metabolism

    The sum of all chemical reactions in an organism, including catabolic (energy-releasing) and anabolic (energy-consuming) pathways.

  • Activation Energy (EA)

    The energy input required to reach the transition state and start a chemical reaction by breaking bonds.

  • Catalysts

    Substances that speed up reactions by lowering activation energy without being consumed.

  • Enzymes

    Protein macromolecules that act as catalysts to speed up specific reactions by stabilizing the transition state.

  • Enzyme Active Site

    The specific region on an enzyme where substrates bind and the reaction is catalyzed.

  • Induced Fit Model

    Substrate binding induces a conformational change in the enzyme, optimizing the fit and catalytic activity.

  • Enzyme Cofactors

    Non-protein helpers required by some enzymes, including inorganic ions (minerals) and organic molecules (coenzymes like vitamins).

  • Regulation of Enzyme Activity

    Enzymes can be regulated by competitive inhibitors (bind active site), non-competitive inhibitors, and allosteric interactions that change enzyme shape.

  • Allosteric Regulation

    Binding of molecules at sites other than the active site that stabilize the enzyme in active or inactive conformations.

  • Cooperativity

    Substrate binding to one active site increases the activity of other active sites in a multi-subunit enzyme.

  • Feedback Inhibition

    The end product of a metabolic pathway inhibits an enzyme early in the pathway to prevent overproduction.

  • Compartmentalization in Metabolism

    Cellular compartments localize enzymes and pathways, increasing efficiency and order in metabolism.

  • Environmental Effects on Enzymes

    Enzyme activity and structure are affected by temperature, pH, and concentrations of enzyme, substrate, and cofactors.