Cellular Energy and Enzymes Vocabulary Flashcards

Vocabulary practice flashcards covering cellular energy, laws of thermodynamics, metabolic pathways, ATP structure and function, enzyme catalysis, and enzyme regulation mechanisms.

Energy

The ability to do work, defined as any change in the state or motion of matter.

Thermodynamics

The study of energy transformations that occur in matter.

First Law of Thermodynamics

The law stating that energy cannot be created or destroyed, only transferred or transformed.

Second Law of Thermodynamics

The law stating that every energy transformation increases the entropy of the universe, with some energy lost as disorganized heat.

Entropy

A measure of the degree of disorder or randomness in a system or the universe.

Metabolism

The sum total of all chemical reactions occurring within a cell that transform energy and matter.

Metabolic Pathway

A sequential series of linked chemical reactions that either break down or build complex molecules, where the product of one step becomes the reactant for the next.

Endergonic Reactions

Chemical reactions that require an overall input of energy to proceed.

Exergonic Reactions

Chemical reactions that release energy.

Adenosine Triphosphate (ATP)

The primary energy-coupling molecule in organisms, structurally composed of adenine, ribose, and three phosphate groups.

Phosphorylation

The process by which a phosphate group released during ATP hydrolysis ($ATP + H_2O \rightarrow ADP + P_i$) is transferred to another molecule, forming a more reactive intermediate.

ATP Cycle

The continuous process in cells where ADP is regenerated back into ATP using energy derived from exergonic reactions.

Enzymes

Biological proteins that catalyze reactions by lowering the activation energy needed for the reaction to start.

Activation Energy

The initial energy input required to start a chemical reaction.

Substrate

The specific reactant molecule upon which an enzyme acts.

Active Site

The specific region on an enzyme where substrate molecules bind and undergo catalysis.

Enzyme-Substrate Complex

The temporary complex formed when a substrate binds to an enzyme's active site, inducing slight shape changes in both to facilitate catalysis.

Cofactors

Non-protein molecules or inorganic metallic ions (e.g., iron, copper, zinc) that bind to enzymes and assist in catalytic function.

Coenzymes

Small organic non-protein compounds that assist enzymes during reactions, often functioning as electron carriers.

Denaturation

The loss of an enzyme's native 3D structure and biological function caused by unfolding under non-optimal environmental conditions.

Enzyme Saturation

The condition reached when all active sites of an enzyme population are bound to substrates, resulting in a maximum reaction rate.

Competitive Inhibitors

Molecules that reduce enzyme activity by competing directly with substrates to bind to the active site.

Noncompetitive Inhibitors

Molecules that decrease enzyme activity by binding to a location other than the active site, causing a conformational change that prevents substrate binding.

Allosteric Site

A specific regulatory site on an enzyme outside of the active site where regulatory molecules bind.

Allosteric Regulation

A form of enzyme regulation where the binding of a molecule (activator or inhibitor) at an allosteric site modifies enzyme activity.

Feedback Inhibition

A metabolic pathway regulation technique in which the final product acts as an allosteric inhibitor to an enzyme early in the same pathway.