Enzyme Activity and Reaction Rate Regulation

Vocabulary flashcards covering key terms from the lecture notes on enzyme activity and its regulation.

Enzyme

A biological molecule that acts as a catalyst to accelerate a chemical reaction by lowering activation energy.

Catalyst

A substance that increases the rate of a chemical reaction without being consumed in the process.

Activation energy

The energy barrier that must be overcome for reactants to proceed to products; enzymes lower this barrier.

Enzymatic activity

The rate at which an enzyme catalyzes its specific chemical reaction.

Optimum temperature

The temperature at which an enzyme’s activity is at its maximum.

Temperature

A major environmental factor that influences enzyme activity; enzymes require appropriate temperatures to function properly.

pH

A major environmental factor affecting enzyme activity; each enzyme has an optimal pH range.

Cofactor

A non-protein chemical required for the proper activity of some enzymes.

Coenzyme

An organic molecule that acts as a cofactor to assist enzyme function.

End product inhibition

Feedback where the final product inhibits an earlier enzyme in the pathway.

Substrate depletion

When substrate becomes scarce, the rate of the enzyme-catalyzed reaction decreases.

Product accumulation

Accumulation of product can shift equilibrium or reduce net forward reaction.

Genetic control (induction and repression)

Regulation of enzyme production by controlling gene transcription, affecting enzyme quantity.

Induction

Increase in enzyme production through upregulation of gene transcription.

Repression

Decrease in enzyme production through downregulation of gene transcription.

mRNA transcription

Process of transcribing DNA into mRNA, leading to synthesis of enzymes.

Enzyme-substrate complex

Temporary complex formed when an enzyme binds its substrate, leading to product formation.

Enzymes are never consumed

Enzymes act as catalysts and are not consumed in the reaction; they can catalyze many cycles.

Lock and Key model

Substrate fits precisely into the enzyme’s active site like a key fits a lock.

Induced fit model

Enzyme changes shape to better accommodate the substrate, aiding catalysis.

Transition state

The high-energy, unstable arrangement that enzymes help substrates achieve during the reaction.

Fully active conformation

The enzyme conformation achieved when substrate binding enables catalysis.

Substrate

A molecule that an enzyme acts upon in a reaction.

Product

A molecule formed from the substrate as a result of the enzyme-catalyzed reaction.

Equilibrium (A + B ⇄ C)

A reversible reaction where forward and reverse processes balance, e.g., A + B ⇄ C.