Enzymes

Catalyst

A substance that increases the rate of a chemical reaction and is not changed by the reaction itself

Enzymes

Proteins that increase the rate of metabolic reactions, where they function as biological catalysts (they are made in living cells).

Importance of enzymes

Crucial to living organisms as they speed up metabolic reactions which would take too long to occur without them, maintains the reaction rates of all metabolic reactions necessary to sustain life

Enzyme Action

The enzyme has a shape called the active site which is complementary to the substrate molecule.
Substrate: the substance on which the enzyme acts.
Products: the molecules produced.
Enzyme-substrate complex: formed temporarily when the enzymes combines with the substrate.

Specificity of Enzymes

Enzymes are specific to their substrate molecules, the active site is complementary to the substrate molecule.
e.g. lock and key mechanism

How enzymes work

1. Substrate enters active site
2. Enzyme substrate complex
3. Enzyme-product complex after reaction occurs in enzyme
4. Products leave active site

Factors affecting Enzyme activity

Temperature, pH

Temperature -

1. The rate of an enzyme-catalysed reaction increases as temperature increases because the molecules gain more energy so they move faster, greater chance of effective molecular collisions.
   2. If temperature is a lot higher than optimum, the enzyme denatures because enzyme bonds break, shape of active site changes.
   3. At low temperatures, molecules travel with less kinetic energy so less successful collision.

pH

Enzymes have an optimum pH. If the pH gets too low or high, it could cause bonds in the protein enzymes to break changing the shape of the active site, and the enzyme is denatured.