Lecture Notes: Enzymes, Water, Acids, and Bases

Key Learning Outcomes

• Understand chemical bond formation and reactions
• Explore energetics of reactions (energy input or output)
• Determine factors affecting reaction rates
• Learn about enzymes and their importance
• Review properties and significance of water
• Understand acids, bases, and pH scale
• Discuss pH buffers in the body

Chemical Energy and Reactions

Types of Reactions

• Endergonic Reactions: Require energy input
  • Example: Photosynthesis (requires sunlight energy)
• Exergonic Reactions: Release energy
  • Example: Cellular respiration (breaks down glucose)

Reaction Notation

• Reactants: Substances entering a reaction, left side of equation
• Products: End result of a reaction
• Intermediates: Temporary products in some reactions

Types of Chemical Reactions

• Decomposition Reaction: AB → A + B
• Synthesis Reaction: A + B → AB
• Exchange Reaction: AB + CD → AC + BD
• Reversible Reactions: Indicated by double arrows

Organic vs Inorganic Compounds

• Organic Compounds: Contain carbon bonded to hydrogen
• Inorganic Compounds: Often lack carbon-hydrogen bonds (e.g., water, acids, bases)

Factors Influencing Reaction Rates

• Concentration: Higher concentration increases reaction rate
• Temperature: Higher temperatures increase kinetic energy and reaction rates
• Reactant Properties: Phase (solid, liquid, gas) affects reaction speed
• Catalysts: Lower activation energy, speed up reactions
  • Biological catalysts in the body are enzymes

Enzymes

• Function: Speed up reactions by lowering activation energy
• Properties:
  • Highly specific to reactions
  • Reusable
  • Sensitive to temperature and pH

Factors Affecting Enzyme Activity

• Temperature: Optimal temperature needed; too high denatures enzymes
• Concentration: Enzyme and reactant concentrations affect rate
• pH: Enzymes require specific pH for optimal function

Water

• Importance: Solvent, heat absorber, cushions body structures
• Properties:
  • Absorbs and retains heat
  • Facilitates chemical reactions
  • Forms hydration spheres around ions

Acids and Bases

• Acids: Release H+ ions, increase acidity
• Bases: Release OH- ions, increase alkalinity
• pH Scale: Measures concentration of H+ ions
  • Scale from 1 (acidic) to 14 (basic), with 7 as neutral
  • Logarithmic scale, where each unit change represents a tenfold change in H+ concentration

Buffer Systems

• Function: Resist rapid pH changes in the body
• Mechanism: Use weak acids/bases to maintain equilibrium
  • Example: Carbonic acid buffer in blood

Measuring pH

• Tools:
  • pH meters for accurate measurements
  • Litmus paper for acidic/basic indication
  • pH indicator solutions

Summary

Understanding the chemistry of enzymes, reactions, water, and pH is crucial for studying biology and biochemistry. These concepts form the foundation for understanding more complex biological processes and systems.