Chemical Reactions and Enzyme Action

Flashcards covering collision theory, methods for speeding up chemical reactions, activation energy, and the mechanics and models of enzyme function.

Collision theory

The theory stating that for a reaction to occur, particles must collide with correct orientation and enough (activation) energy.

Activation energy ($E_A$)

The minimum energy needed to start a chemical reaction, functioning like a hill reactants need to climb before they can become products.

Catalyst

A substance that speeds up reactions without being changed or used up, allowing it to be reused over and over; it lowers the activation energy required and orients particles correctly.

Enzyme

A biological catalyst made by living organisms, almost always composed of proteins formed by a long chain of amino acids folded into a specific 3D shape.

Substrate

The reactant that an enzyme acts on.

Product

What a chemical reaction makes; enzymes produce them by breaking a substrate into smaller pieces or joining several substrates into one.

Active site

The region of an enzyme with a shape complementary to the substrate; if the substrate does not fit, the reaction is not catalyzed.

Lock and key model

The older model of enzyme action stating that the substrate fits into the active site perfectly, like a lock and key.

Induced fit model

The current model of enzyme action stating that the enzyme changes shape slightly when the substrate binds, molding around the substrate for a better fit.

Collision theory

The concept stating that for a chemical reaction to occur, reacting particles must collide with the correct orientation and with enough (activation) energy.

Activation energy ($E_A$)

The minimum energy needed to start a reaction, functioning like a hill that reactants must climb before they can become products.

Concentration (reaction rate factor)

A factor that speeds up reactions either by decreasing volume (bringing particles closer together) or adding more particles, resulting in more frequent collisions.

Temperature (reaction rate factor)

A factor that speeds up reactions by making particles move faster, leading to more collisions that possess enough energy.

Surface area (reaction rate factor)

A factor that speeds up reactions by ensuring particles do not travel in packs, leaving more particles exposed so more collisions can happen.

Catalyst

A substance that speeds up reactions without being changed or used up (allowing it to be reused over and over) by lowering the required activation energy and orienting particles correctly.

Enzyme

A biological catalyst made by living organisms, almost always composed of proteins (long chains of amino acids folded into a specific 3D shape) where each distinct amino acid sequence and shape catalyzes one specific reaction.

Substrate

The specific reactant that an enzyme acts on.

Product

What a chemical reaction makes when enzymes break a substrate into smaller pieces or join several substrates into one.

Active site

The region of an enzyme with a shape complementary to the substrate; responsible for enzyme specificity because if the substrate does not fit, the reaction is not catalyzed.

Lock and key model

The older model of enzyme action proposing that the substrate fits the active site perfectly, analogous to a key fitting into a lock.

Induced fit model

The current model of enzyme action stating that the enzyme changes shape slightly when the substrate binds, molding around the substrate for a better fit.