Biology Chapter: Enzyme Function and Activity

Learning Objectives

• Define 'metabolism'

• Compare solar and cellular energy

• Define 'enzymes' and describe their structure and function in plant and animal metabolism

• Explain the use of immobilised enzymes in bioprocessing

• Detail enzyme immobilisation and its applications

• Explain and investigate the effect of pH and temperature on enzyme activity

Sources of Energy

• Solar energy is energy from the sun.

• Cellular energy is energy stored in the bonds within biomolecules (carbohydrates, lipids, proteins, and nucleic acids).

Catalysts and Enzymes

• A catalyst speeds up a reaction without being consumed in the process.

• Enzymes are protein catalysts that speed up reactions without being consumed.

• Enzymes are biological (or organic) catalysts, produced in living things.

Enzyme Characteristics

• Enzymes are proteins, manufactured in ribosomes.

• Enzymes are specific, only working with certain substrates.

• Enzymes function correctly only if they have the correct 3D shape.

• Enzyme names usually end in "ase". Examples: lipase (acts on lipids), amylase (acts on amylose, a type of starch).

Enzyme Action

• Enzymes have an active site where substrates bind.

• The substrate fits into the active site, like a lock and key.

• The enzyme speeds up reactions by lowering the activation energy.

• Starch is broken down by amylase to form maltose.

Metabolism

• Metabolism is the sum of all chemical reactions that take place within an organism.

• Metabolism controls the chemical and energy requirements of a cell, maintaining homeostasis (internal balance) within the organism.

Catabolic Reactions

• Catabolic reactions break down complex molecules into smaller ones, like the digestion of starch by amylase into maltose, releasing energy.

Anabolic Reactions

• Anabolic reactions build up complex molecules from smaller ones, e.g., photosynthesis, or DNA polymerase building DNA. They require energy.

Factors Affecting Enzyme Activity

• Temperature: Enzyme activity increases with temperature until reaching an optimum. Moving past the optimum causes enzymes to denature.

• pH: Enzymes typically have an optimum pH range; changes in pH cause enzymes to denature.

Immobilised Enzymes

• Immobilised enzymes are trapped in a material, typically a gel or bead.

• This prevents the enzyme from diffusing or being lost.

• This simplifies recovery and allows reuse.

• The enzyme is separated from the products, which is better for industrial applications.

Bioprocessing

• Bioprocessing is the use of enzyme-controlled reactions to make products.

• This can manufacture many things like cheeses, beer, antibiotics, vaccines and food flavourings.

Catalase

• Catalase is an enzyme found in many organisms. It converts hydrogen peroxide, a toxic substance, into water and oxygen.

Experimental Methods - Temperature Effects

• Vary temperatures to test catalase activity.

• Monitor the produced foam volume.

Experimental Methods - pH Effects

• Introduce various pH buffers.

• Observe effects on catalysed reactions.

Enzyme Immobilisation Experiment - Procedure

• Techniques used to immobilise enzymes include adsorption, covalent bonding, trapping in a membrane or gel.

• Equipment includes beakers, stirring rods, electronic balance, graduated cylinder, syringes, distilled water, sodium alginate, yeast, calcium chloride.

• Procedures involve mixing solutions, releasing drops, and hardening time periods at specific temperatures.