BIOL201-Enzymes

BIOL 201 Week 5 Study Guide

Enzymes and Their Biological Role

• Big Idea: Life consists of chemical reactions, many catalyzed by enzymes.

• Metabolic Pathways: An ordered series of chemical reactions.

Learning Outcomes

• EO5: Apply chemical principles to enzymes' roles.

  • Describe/model energetic processes of chemical reactions, including enzyme roles.

  • Predict the impact of environmental changes on enzyme structure and function.

Reading Assignments

• Chapter 3: Protein structure and function (Sections 3.2, 3.4)

• Chapter 8: Energy and enzymes: Introduction to Metabolism (Sections 8.1–8.5)

Part 1: Enzyme Structure and Function

• Most Enzymes Are Proteins

  • Proteins’ functions are determined by their structure (structure affects function).

  • Familiarize with protein monomers (amino acids).

  • Sketch Examples:

    • Amino acid with acidic side chain

    • Amino acid with polar side chain

    • Amino acid with nonpolar side chain

Levels of Protein Structure

• Primary Structure: Sequence of amino acids.

• Secondary Structure: Local folding (e.g., alpha helices, beta sheets).

• Tertiary Structure: Overall 3D shape of a polypeptide.

• Quaternary Structure: Assembly of multiple polypeptides.

• Example Application: Discuss lactase's structure and whether it has quaternary structure.

• Enzyme Definition: A biological catalyst, facilitating biochemical reactions (most are proteins but some are RNA).

• Active Site: Region where substrates bind and react.

Part 2: Energetics of Chemical Reactions

• Definition of Energy: Capacity to do work or supply heat.

• Energy Types:

  • Potential Energy: Stored energy (e.g., C—C and C—H bonds in glucose).

  • Kinetic Energy: Energy of motion (e.g., sound, thermal energy).

• Thermodynamics:

  • 1st Law of Thermodynamics: Energy is conserved in any process.

  • 2nd Law of Thermodynamics: Entropy of the universe always increases.

• Endergonic vs. Exergonic Reactions:

  • Endergonic: Absorbs energy (positive ΔG)

  • Exergonic: Releases energy (negative ΔG)

• Reaction Rates: Increasing temperature/concentration boosts reaction rates.

Part 3: Importance of ATP

• ATP Model: Contains three phosphate groups.

• ATP Hydrolysis Equation:

  • ATP + H2O → ADP + Pi + Energy (approx. 7.3 kcal/mol, Exergonic).

• Importance of ATP: Key energy carrier in cells.

• Example Reaction: Applying reaction (A + B → A-B) to bodily functions.

Part 4: Enzyme Function Mechanism

• Free Energy Change: Understand ΔG in reactions.

  • Graph Sketch: Label reactions as endergonic/exergonic.

  • Activation Energy: Enzymes lower activation energy, speeding up reactions.

• Enzyme Tasks:

  1. Facilitate substrate interaction through lower activation energy.

  2. Specific binding to substrates.

Part 5: Factors Affecting Reaction Speed

• Factors Influencing Enzyme Function:

  • Temperature, pH, substrate concentration affect reaction rate.

• Optimization: Enzymes tailored for specific environmental conditions.

• Metabolic Pathways:

  • Catabolic Pathways: Breakdown of macromolecules (e.g., digestive system).

  • Anabolic Pathways: Synthesis of macromolecules (e.g., blood cell formation).