An Introduction to Metabolism

These vocabulary flashcards cover the fundamental principles of metabolism, thermodynamics, energy transformations, ATP function, and enzyme regulation as presented in the lecture notes.

Metabolism

The complete set of chemical reactions that occur within an organism, representing an emergent property of life.

Metabolic Pathway

A sequence of steps where a specific molecule is transformed into a product, with each stage typically facilitated by a specific enzyme.

Catabolic Pathways

Metabolic processes that release energy by breaking down complex molecules into simpler ones, such as cellular respiration.

Anabolic Pathways

Energy-consuming metabolic processes that build complex molecules from simpler components, such as protein synthesis.

Bioenergetics

The study of the flow of energy through living systems.

Kinetic Energy

The energy associated with the relative motion of objects.

Thermal Energy

A form of kinetic energy related to the random movement of atoms or molecules; its transfer between objects is known as heat.

Potential Energy

The energy an object possesses due to its position or spatial arrangement (structure).

Chemical Energy

A type of potential energy stored in the arrangement of atoms in molecules that is available for release during a chemical reaction.

Thermodynamics

The study of energy transformations that occur in a specific collection of matter.

First Law of Thermodynamics

The principle stating that energy in the universe is constant; it can be transferred or transformed but neither created nor destroyed.

Second Law of Thermodynamics

The principle stating that every energy transfer or transformation increases the total disorder (entropy) of the universe.

Entropy

A scientific measure of molecular disorder or randomness within a system.

Spontaneous Process

A process that can occur without an external input of energy, leading to an increase in entropy.

Free Energy ($G$)

The portion of a system's energy capable of performing work when temperature and pressure are uniform throughout.

Free Energy Change Formula

$\Delta G = \Delta H - T\Delta S$ representing the change in enthalpy, temperature in Kelvin, and change in entropy.

Exergonic Reaction

A chemical reaction that proceeds with a net release of free energy ($\Delta G < 0$) and is considered spontaneous.

Endergonic Reaction

A nonspontaneous chemical reaction that absorbs free energy from its surroundings ($\Delta G > 0$).

Energy Coupling

The strategy used by cells to manage energy resources by using an exergonic process to power an endergonic one.

ATP (Adenosine Triphosphate)

An organic molecule consisting of ribose, adenine, and three phosphate groups that serves as the primary energy carrier in cells.

Phosphorylation

The transfer of a phosphate group from ATP to another molecule, typically making the recipient (phosphorylated intermediate) more reactive.

Enzyme

A macromolecular catalyst (usually a protein) that speeds up chemical reactions without being consumed in the process.

Activation Energy ($E_A$)

The initial investment of energy required to contort reactant molecules so that their bonds can break.

Substrate

The specific reactant molecule that an enzyme acts upon.

Active Site

The specific pocket or groove on the surface of an enzyme where the substrate binds and catalysis occurs.

Induced Fit

The tightening of the enzyme's binding site around the substrate after initial contact to enhance its catalytic ability.

Cofactors

Nonprotein helpers, either inorganic (like metal ions) or organic (coenzymes like vitamins), required for proper enzyme activity.

Competitive Inhibitors

Chemicals that reduce enzyme productivity by mimicking the substrate and blocking the active site.

Noncompetitive Inhibitors

Inhibitors that bind to a part of the enzyme other than the active site, causing a shape change that renders the active site less effective.

Allosteric Regulation

A regulatory mechanism where a molecule binds to a protein at one site, affecting its function at a separate site.

Feedback Inhibition

A metabolic control method where the final product of a pathway acts as an inhibitor for an enzyme earlier in that pathway.