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).

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