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• Biomolecule


  Any molecule that is produced by a living organism and includes large macromolecules such as proteins, polysaccharides, lipids and nucleic acids
• Food is a source of biomolecules or large molecules needed for life
• According to one saying, "you are what you eat"
• Biomolecules are larger than an atom or a molecule but smaller than an organelle, cell, tissue, organ or organ system
• Four main types of biomolecules

  • Carbohydrates
  • Proteins
  • Nucleic acids
  • Lipids
• Carbohydrates


  The primary energy source of our body, and are sugars
• Monomer

  The building block or smaller unit from which larger molecules are made
• Carbohydrate monomers (monosaccharides)


  • Glucose
  • Fructose
  • Galactose
• Disaccharide


  A carbohydrate formed by combining two monosaccharides
• Polysaccharides


  • Starch
  • Glycogen
  • Cellulose
  • Chitin
• Starch


  • Used for energy storage in plants, provides quick energy for the body
• Glycogen


  • Used for energy storage in animals, stored in the liver and muscles
• Cellulose


  • Found in plant cell walls and bark, provides dietary fiber
• Chitin


  • Forms the exoskeleton of insects and crustaceans
• Iodine test for starch


  Add iodine, violet colour indicates presence of starch
• Benedict's test for simple carbohydrates


  Benedict's solution changes colour from blue to green, yellow, orange, red or brick red depending on sugar content
• Protein


  Body building molecules that help us grow, transport molecules, and control chemical reactions
• Amino acid


  The monomer or building block of proteins
• Protein sources

  • Soy, egg albumin, hemoglobin, enzymes
• Biuret test for proteins


  Reagent changes from blue to purple, indicating presence of peptide bonds
• Nucleic acids


  Important components in heredity, present in DNA
• Nucleotide


  The monomer or building block of nucleic acids
• Lipids


  Energy-giving molecules, commonly stored energy molecules
• Fatty acid


  The monomer or building block of lipids
• Lipids


  • Provide protection for internal organs, serve as waterproof coverings
• Saturated fat


  Solid at room temperature, e.g. butter
• Unsaturated fat


  Liquid at room temperature, e.g. oils
• Ethanol emulsion test for lipids


  Presence of lipids is indicated by cloudiness when mixed with ethanol