effecf of temperature on enzyme activity

What are enzymes?

Enzymes are biological catalysts that speed up chemical reactions in living organisms without being used up.

What is the relationship between temperature and kinetic energy in enzyme reactions?

As temperature increases, enzyme and substrate molecules gain more kinetic energy and move faster.

How does increasing temperature (up to the optimum) affect the rate of reaction?

The rate increases because there are more frequent successful collisions between the substrate and the enzyme's active site.

What is meant by the "optimum temperature" for an enzyme?

The specific temperature at which the enzyme works at its fastest rate (approximately 37^{\circ}C for most human enzymes).

What happens to the enzyme's structure when the temperature exceeds the optimum?

High temperatures break the chemical bonds holding the enzyme's protein structure together, changing the shape of the active site.

What is the term used when an enzyme's active site changes shape and can no longer bind to a substrate?

The enzyme is said to be denatured.

Why is a denatured enzyme unable to function?

The shape of the active site is no longer complementary to the substrate, so the substrate can no longer fit (Lock and Key theory).

Is denaturation due to high temperature reversible?

No, denaturation is an irreversible change to the protein's structure.

Describe the typical shape of a graph showing enzyme activity vs. temperature.

The rate increases steadily until it reaches a peak at the optimum temperature, after which it drops rapidly to zero.

Why does the rate of reaction drop so sharply after the optimum temperature is reached?

Because enzymes begin to denature rapidly, and once the active site's shape is lost, the reaction cannot occur.