Enzymes & Metabolism Flashcards

All 6 cards in this deck

What is an enzyme?

A biological catalyst — a protein that speeds up a reaction without being used up.

What is the active site of an enzyme?

The part of the enzyme where the substrate binds; its shape is complementary to the substrate.

What does the 'lock and key theory' say about how an enzyme works?

The substrate binds to the active site because the shapes of the substrate and active site are complementary, so each enzyme catalyses only one specific reaction.

How does temperature affect the rate of an enzyme-controlled reaction?

The rate increases up to the optimum temperature, then falls sharply as the enzyme denatures.

What does it mean if an enzyme has been denatured?

The shape of its active site has changed, so the substrate no longer fits and the reaction stops.

True or false? All enzymes work best at pH 7.

False. Each enzyme has its own optimum pH — e.g. stomach protease works best at about pH 2.