GAP Ch2 (part 2)

Chemical Reactions in the Body

• Reactants and Products

  • Chemical reactions start with reactants (substances involved in the reaction) and end with products (substances produced).

  • Example: In a synthesis reaction, reactants A and B combine to yield product AB.

• Types of Chemical Reactions

  • Synthesis Reaction (Anabolic)

    • Combines components to create larger molecules.

    • Example: A + B → AB

    • Requires energy, stored in the compound's chemical bonds.

  • Decomposition Reaction (Catabolic)

    • Breaks down larger molecules into smaller parts.

    • Example: AB → A + B

    • Releases energy.

  • Exchange Reaction

    • Involves both synthesis and decomposition.

    • Bonds are broken and formed.

    • Example: AB + CD → AC + BD

Role of Enzymes in Chemical Reactions

• Activation Energy

  • The energy required to start a chemical reaction.

  • Enzymes lower activation energy, increasing reaction rates without changing themselves.

• Catalysts

  • Substances like enzymes that speed up reactions.

  • Without enzymes, body processes would require much more energy, impacting metabolism.

Importance of Water in Biological Reactions

• Inorganic Compound

  • Water (H2O) is vital, comprising about 70% of adult body weight.

• Functions of Water

  • Lubrication: Provides cushioning for joints and organs.

  • Heat Sink: Absorbs heat during chemical reactions without significant temperature increase.

  • Universal Solvent: Facilitates chemical reactions by dissolving other substances.

• Types of Reactions Involving Water

  • Dehydration Synthesis:

    • Monomers bond to form polymers, releasing water.

    • Example: A + B → AB + H2O

  • Hydrolysis:

    • Water is added to split monomers, breaking bonds.

    • Example: AB + H2O → A + B

Salts, Acids, and Bases

• Salts

  • Dissociate into ions when dissolved in water (not H+ or OH-).

  • Example: Sodium Chloride (NaCl) dissociates into Na⁺ and Cl⁻.

• Acids

  • Release H+ ions in solution.

  • Example: HCl → H+ + Cl-

• Bases

  • Release OH- ions or accept H+, reducing acidity.

  • Example: NaOH → Na+ + OH-

• pH Scale

  • Ranges from 0 (acidic) to 14 (basic), with 7 as neutral.

Organic Compounds Essential for Life

• Two main categories: Inorganic (no carbon-hydrogen bonds) vs Organic (contain both).

• Types of Organic Compounds

  • Carbohydrates

    • Composed of carbon, hydrogen, and oxygen (CH₂O).

    • Forms: Monosaccharides (e.g., glucose), disaccharides (e.g., sucrose), polysaccharides (e.g., starch).

  • Lipids

    • Hydrophobic compounds, do not mix well with water.

    • Types: Triglycerides (energy storage), phospholipids (cell membranes), steroids (e.g., cholesterol), prostaglandins (signaling molecules).

  • Proteins

    • Made of amino acids linked by peptide bonds.

    • Structure determines function (e.g., hemoglobin in red blood cells).

    • Proteins can be denatured, losing their functional shape.

  • Nucleic Acids

    • Composed of nucleotides (phosphate group, sugar, nitrogenous base).

    • Types: DNA (stores genetic info), RNA (helps in protein synthesis), ATP (energy currency).

• Summary of Protein Structure

  • Proteins can have primary, secondary, tertiary, and quaternary structural levels, each contributing to function and specificity of action.