(chapter 6 bio) Metabolism and Bioenergetics

Vocabulary practice flashcards covering chapter 6 energy, metabolism, enzyme kinetics, and ATP mechanics from Biology 2e lecture notes.

Bioenergetics

The study of energy flow through a living system.

Metabolism Classification Scheme

A system categorizing all organisms based on primary energy source into Phototrophs (light) or Chemotrophs (chemicals), with Chemotrophs further divided into Chemolithotrophs (inorganic chemicals) and Chemoorganotrophs (organic chemicals).

Chemotrophs

Organisms that use chemical compounds as their primary energy source.

Phototrophs

Organisms that use light as their primary energy source.

Chemolithotrophs

Chemotrophic organisms that use inorganic chemicals as their primary energy source.

Chemoorganotrophs

Chemotrophic organisms that use organic chemicals as their primary energy source.

Metabolism

The sum of all chemical reactions occurring within a cell or organism.

Metabolic Pathway

A series of biochemical reactions that converts one or more substrates into a final product.

Anabolic Pathways

Metabolic processes that require energy to synthesize large, complex molecules from smaller ones.

Catabolic Pathways

Metabolic processes that release energy by breaking down large, complex molecules into smaller ones.

First Law of Thermodynamics

A physical law stating that the total amount of energy in the universe is constant, meaning energy cannot be created or destroyed.

Second Law of Thermodynamics

A physical law stating that energy transfers are not completely efficient, resulting in energy lost as unusable heat and increasing system entropy (disorder).

Kinetic Energy

The form of energy associated with objects or particles in motion.

Potential Energy

The energy stored in an object or system due to its position or structure, such as energy stored in chemical bonds or membrane gradients.

Activation Energy

The energy required for a chemical reaction to proceed, which contorts reactants into an unstable state to allow bonds to break or form.

Transition State

The high-energy, unstable contorted state of reactants necessary for chemical bonds to be broken or formed.

Exergonic Reaction

A spontaneous chemical reaction that releases free energy, characterized by $ΔG < 0$.

Endergonic Reaction

A non-spontaneous chemical reaction that requires an input of energy, characterized by $ΔG > 0$.

Enzymes

Protein catalysts (or non-protein ribozymes) that accelerate chemical reactions by lowering the required activation energy.

Cofactors

Inorganic ions, such as $Fe^{2+}$, $Mg^{2+}$, and $Zn^{2+}$, required by certain enzymes to function properly.

Coenzymes

Organic molecules, including ATP, $NAD^+$, and vitamins, that serve as helper molecules required for enzyme function.

Adenosine Triphosphate (ATP)

The primary energy currency of the cell, consisting of an adenosine backbone (adenine base and ribose sugar) attached to three phosphate groups (alpha, beta, and gamma).

ATP Hydrolysis

A reversible exergonic reaction where ATP reacts with water to yield ADP, inorganic phosphate ($P_i$), and free energy ($ΔG = -7.3\,kJ\,mol^{-1}$ or $-7.3\,kcal\,mol^{-1}$).

Sodium-Potassium Pump

An integral membrane protein that utilizes exergonic ATP hydrolysis to actively transport $3\,Na^+$ ions out of the cell and $2\,K^+$ ions into the cell.

ATPase

An integral membrane protein enzyme that synthesizes ATP from ADP and $P_i$ by consuming a proton ($H^+$) accumulation across a membrane.