Biological Molecules

Chemistry - Part 2

  • Focus: Biological Molecules, Macromolecules, Organic Molecules

Key Terms to Know

  • Monomers: Small, single units that join together to form polymers.

  • Polymers: Larger molecules made from the combination of many monomers.

  • Dehydration Synthesis: A chemical reaction that joins monomers to form polymers by removing water (conden sation reaction).

  • Hydrolysis: A process that breaks down polymers into monomers by adding water.

Dehydration Synthesis and Hydrolysis

  • Dehydration Reaction: When two monomers combine, a water molecule is released, forming a polymer.

  • Hydrolysis Reaction: Water is added, breaking the polymer down into monomers.

Macromolecules

  • Types of Macromolecules:

    • Carbohydrates: Composed of monosaccharides (e.g., glucose).

    • Lipids: Composed of fatty acids and glycerol (not strictly monomers).

    • Proteins: Made up of amino acids.

    • Nucleic Acids: Comprised of nucleotides (e.g., DNA/RNA).

Covalent Bonds in Macromolecules

  • Carbohydrates: Formed via glycosidic linkages.

  • Lipids: Formed through ester linkages.

  • Proteins: Comprised of peptide linkages.

  • Nucleic Acids: Formed via phosphodiester linkages.

Carbohydrates

  1. General Formula: (CH2O)

  2. Types:

    • Monosaccharides: Simple sugars (e.g., glucose).

    • Disaccharides: Formed by two monosaccharides (e.g., sucrose from glucose and fructose).

    • Polysaccharides: Long chains of monosaccharides (e.g., starch, glycogen).

Monosaccharides

  • Glucose Structure: C6H12O6, a simple sugar that is a primary energy source.

Disaccharides

  • Examples:

    • Sucrose: Glucose + Fructose.

    • Lactose: Galactose + Glucose.

    • Maltose: Glucose + Glucose.

Polysaccharides

  • Storage Polysaccharides:

    • Glycogen: Energy storage in animals, found in liver.

    • Starch: Energy storage in plants.

  • Structural Polysaccharides:

    • Cellulose: Main component of plant cell walls.

    • Chitin: Found in exoskeletons of insects.

Lipids

  1. Characteristics: Nonpolar molecules, includes fats, phospholipids, and steroids.

  2. Fatty Acids:

    • Triglycerides: Made from glycerol and three fatty acids.

    • Saturated Fatty Acids: No double bonds, solid at room temperature (e.g., butter).

    • Unsaturated Fatty Acids: One or more double bonds, liquid at room temperature (e.g., olive oil).

Phospholipids

  • Composed of fatty acids and a phosphate group forming bilayers in cell membranes.

Steroids

  • Structure: Four fused rings (e.g., cholesterol, testosterone).

Proteins

  1. Building Blocks: Amino acids.

  2. Structure Formation:

    • Peptide Bonds: Formed through dehydration synthesis between amino acids.

    • Levels of Protein Structure:

      • Primary: Sequence of amino acids.

      • Secondary: Folding into alpha-helixes or beta sheets.

      • Tertiary: 3D structure formed by folding.

      • Quaternary: Assembly of multiple polypeptides.

  3. Functions of Proteins:

    • Enzymatic, structural, storage, transport, hormone, receptor, contractile, and defensive proteins.

Nucleic Acids

  1. Components:

    • Nucleotides: Base units comprising a sugar, phosphate group, and nitrogenous base.

  2. DNA Structure:

    • Double helix comprised of nitrogenous bases: Adenine (A), Thymine (T), Guanine (G), Cytosine (C).

  3. RNA Structure:

    • Single-strand structure containing Uracil (U) instead of Thymine.