Enzymes

What is a catalyst?

A substance which increases the rate of reaction without being used up or changed itself

What are enzymes?

Biological catalysts that speed up the rate of metabolic reaction

Describe the structure of enzymes

Proteins that contain a highly specific active site that fits a specific substrate

Why are enzymes necessary in biological systems?

They speed up reactions so that less energy is needed for the reaction to occur

Describe enzyme action

A substrate that fits the specific active site of the enzyme binds to create an enzyme-substrate complex, a reaction occurs and the products are released

What does the statement ‘enzymes are highly specific’ mean?

The active site of enzymes must bind to a substrate that has a complementary shape and so only specific reactions can be catalyzed

State 4 factors that can affect the rate of an enzyme-controlled reaction

Temperature, pH, Substrate concentration, Enzyme concentration

Describe the effect of temperature on the rate of an enzyme-controlled reaction

• As the temperature increases, so does the rate of reaction

• Once the temperature exceeds the optimum, the enzyme denatures and the rate of reaction decreases

If temperature increases above the optimum, how does this affect enzyme function?

The active site will be distorted as the enzyme denatures and so it will no longer fit the substrate

Describe the effect of pH on the rate of reaction of an enzyme-controlled reaction