VIDEO: Understanding Enzymes and Their Functions

Oct 4, 2024

Lecture Notes on Enzymes

Introduction to Enzymes

  • Enzymes are a type of protein that speed up chemical reactions (catalysts).
  • Essential for maintaining life by enabling fast enough reactions to sustain cellular functions.

Chemical Reactions Recap

  • Chemical reactions involve breaking and re-forming molecular bonds:
    • Reactants: Molecules before the reaction.
    • Products: New molecules formed after the reaction.
    • Example: Cellular Respiration (Glucose + Oxygen -> CO2 + Water + ATP).

Role of Enzymes

  • Enzymes lower the activation energy needed for reactions:
    • Activation energy: Energy required to start a chemical reaction.
  • Enzymes do not get consumed in the reaction, allowing them to catalyze multiple reactions.
  • Provide specificity by catalyzing specific reactions (e.g., enzymes for cellular respiration).

Mechanism of Enzyme Function

  • Active Site: Specific site on an enzyme where reactants bind.
    • Has a specific 3D shape that fits the reactants (like a lock and key).
  • Enzymes reduce activation energy by:
    • Correctly orienting reactants.
    • Stressing reactant bonds to make them easier to break.
    • Sometimes altering the microenvironment (e.g., pH) to facilitate reactions.

Factors Affecting Enzyme Activity

  1. Enzyme Concentration
    • Increasing enzymes increases reaction rate until a saturation point.
  2. Temperature
    • Higher temperatures increase reaction rates up to a point after which enzymes denature.
  3. pH Levels
    • Enzymes have an optimal pH range; deviation can lead to denaturation.
  4. Presence of Inhibitors or Activators
    • Inhibitors: Reduce enzyme activity.
      • Competitive Inhibitors: Compete with reactants for the active site.
      • Non-competitive (Allosteric) Inhibitors: Bind elsewhere, altering the active site's shape.
    • Activators: Increase enzyme efficiency.
      • Cofactors/Coenzymes: Bind to the active site to enhance reaction.
      • Allosteric Activators: Bind elsewhere to stabilize the active site's shape.
      • Cofactors are typically inorganic; coenzymes are organic.

Summary

  • Enzymes are crucial biological catalysts that ensure essential chemical reactions occur efficiently and appropriately within cells.
  • Understanding the role of enzymes, factors affecting their activity, and how they are regulated is vital for grasping biochemical processes.