Biology 2E Chapter 6: Metabolism Flashcards

This set of flashcards covers the fundamental vocabulary of cellular metabolism, including energy classifications, thermodynamics, enzyme function, and the role of ATP, based on Chapter 6 of the Biology 2E curriculum.

Bioenergetics

The study of energy flow through a living system.

Chemotrophs

Organisms that use chemical compounds as their primary energy source.

Phototrophs

Organisms that use light as their primary energy source.

Chemolithotrophs

Organisms that use inorganic chemicals as an energy source.

Chemoorganotrophs

Organisms that use organic chemicals as an energy source.

Metabolism

All chemical reactions of a cell or organism.

Metabolic pathway

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

Anabolic

Metabolic pathways that require energy and synthesize large molecules.

Catabolic

Metabolic pathways that release energy and break down large molecules into smaller molecules.

First law of thermodynamics

States that the total amount of energy in the universe is constant; energy cannot be created or destroyed.

Second law of thermodynamics

States that the transfer of energy is not completely efficient, resulting in some energy being lost as unusable heat and increased entropy (disorder).

Kinetic energy

The energy possessed by objects in motion.

Potential energy

The energy possessed by objects that have the potential to move, including chemical energy stored in bonds.

Activation energy

The energy required for a reaction to proceed, which causes reactants to become contorted and unstable.

Transition state

An unstable state during a chemical reaction that allows bond(s) to be broken or made.

Exergonic

A chemical reaction that releases energy, characterized by $\Delta G < 0$ and being spontaneous.

Endergonic

A chemical reaction that requires an input of energy, characterized by $\Delta G > 0$.

Enzymes

Protein catalysts that speed up reactions by lowering the required activation energy.

Cofactors

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

Coenzymes

Organic molecules, such as ATP, $NADH^{+}$, and vitamins, required by some enzymes to function.

ATP (Adenosine Triphosphate)

A molecule composed of an adenosine backbone with three phosphate groups (alpha, beta, and gamma) attached; used as the primary energy source for endergonic reactions.

ATP Hydrolysis

The reversible reaction where ATP and water produce ADP, inorganic phosphate, and free energy, represented as $\text{ATP} + \text{H}_2\text{O} \rightarrow \text{ADP} + \text{P}_i + \text{free energy}$, with a $\Delta G$ of $-7.3\,kcal/mol$.

Sodium-potassium pump

An example of energy coupling where ATP hydrolysis is used to pump $3$ sodium ions out of the cell and $2$ potassium ions into the cell.

ATPase

An integral protein enzyme that creates ATP from $ADP + P_i$ by consuming the flow of $H^+$ from a high concentration to a low concentration.

NAD+

The oxidized form of a coenzyme that facilitates redox reactions without being consumed.

NADH

The reduced form of a coenzyme that acts as an electron donor in redox reactions.