Bioenergetics: The Flow of Energy in the Cell (World: The Cell, Becker's 10th Edition)

Vocabulary flashcards covering key terms and definitions from the lecture on bioenergetics and the flow of energy in the cell.

Four essential cellular needs

Molecular building blocks, chemical catalysts (enzymes), information to guide activities, and energy to drive reactions.

Molecular building blocks

Basic units for biomolecules (e.g., sugars, amino acids, nucleotides, lipids).

Chemical catalysts (enzymes)

Molecules that speed up chemical reactions in the cell.

Information

Genetic and regulatory data that guide cellular activities and processes.

Energy (cellular)

Capacity to drive reactions and essential life processes.

Phototroph

Organism that obtains energy from light.

Photoautotroph

Phototroph that uses CO2 to synthesize carbon compounds via photosynthesis.

Photoheterotroph

Phototroph that uses light for energy but relies on organic carbon.

Chemotroph

Organism that gains energy by oxidizing chemical bonds in molecules.

Chemoautotroph

Chemotroph that oxidizes inorganic compounds and uses CO2 as carbon source.

Chemoheterotroph

Chemotroph that uses organic compounds for energy and carbon.

Autotroph

Organism that uses inorganic carbon (CO2) as carbon source.

Heterotroph

Organism that uses organic molecules for carbon and energy.

Potential energy

Stored energy; includes chemical potential, concentration gradient, and electric potential.

Kinetic energy

Energy of motion; includes thermal, radiant, and electric energy.

Activation energy

Energy required to reach the transition state of a reaction.

Transition state

Highest-energy intermediate state along a reaction path.

Catalyst

Substance that lowers activation energy to speed up a reaction.

Exergonic

ΔG < 0; energy released; reaction is spontaneous.

Endergonic

ΔG > 0; energy input required; reaction is not spontaneous.

ΔG (Gibbs free energy change)

Change in free energy; predicts the direction and spontaneity of a reaction.

ΔG°′ (standard free energy change)

ΔG under standard conditions (pH 7, 298 K, 1 M) used to compare reactions.

Equilibrium constant (Keq)

Ratio of products to reactants at equilibrium under standard conditions.

Reaction quotient (Q)

Current ratio of products to reactants; used to assess progress toward equilibrium.

Dissociation constant (Kd)

Affinity measure for binding; lower Kd = higher affinity; reciprocal of binding constant.

Steady-state

Concentration remains constant due to balanced inputs/outputs, not necessarily at equilibrium.

ATP hydrolysis

ATP + H2O → ADP + Pi; releases about 7.3 kcal/mol of energy under standard conditions.

Coupled reactions

Linking an unfavorable reaction to a favorable one (e.g., ATP hydrolysis) to drive the overall process.