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Chapter 4: Enzymes

Enzymes

Are biological catalysts made of proteins. They alter the rate of chemical reactions without being chemically changed at the end of reaction and are specific nature.

Enzyme-Catalysed Reaction:

  • Amylase digests starch.

  • Cellulase digests cellulose (only in plants not in humans).

  • Protease digests proteins.

  • Lipase digests fats.

Characteristics of Enzymes:

  • Speed up chemical reactions.

  • Required in minute amounts.

  • Are specific.

Factors affecting Enzyme Activity:

  • pH: they work best at optimum pH. As pH moves away from the pH scale the rate of reaction decreases. A change in pH causes the shape of active site to change.

  • Temperature: works best at optimum temperature. At a temperature above optimum temperature the enzyme denatures.

  • Enzyme and Substrate concentration: as the substrate concentration increases the rate of reaction increases to an initial point to make reaction constant + Increase in enzyme concentration increases rate of enzyme reaction.

Lock and Key hypothesis:

HS

Chapter 4: Enzymes

Enzymes

Are biological catalysts made of proteins. They alter the rate of chemical reactions without being chemically changed at the end of reaction and are specific nature.

Enzyme-Catalysed Reaction:

  • Amylase digests starch.

  • Cellulase digests cellulose (only in plants not in humans).

  • Protease digests proteins.

  • Lipase digests fats.

Characteristics of Enzymes:

  • Speed up chemical reactions.

  • Required in minute amounts.

  • Are specific.

Factors affecting Enzyme Activity:

  • pH: they work best at optimum pH. As pH moves away from the pH scale the rate of reaction decreases. A change in pH causes the shape of active site to change.

  • Temperature: works best at optimum temperature. At a temperature above optimum temperature the enzyme denatures.

  • Enzyme and Substrate concentration: as the substrate concentration increases the rate of reaction increases to an initial point to make reaction constant + Increase in enzyme concentration increases rate of enzyme reaction.

Lock and Key hypothesis: