3.3

• Carbohydrates

  Provide fuel that makes all other reactions of life possible, contain carbon, hydrogen, and oxygen
• Simple sugars


  Carbohydrates containing only one or two sugar units
• Complex carbohydrates


  Made up of long chains of simple sugar units bonded together, e.g. starch and cellulose
• Carbohydrate-rich foods


  • Bread, potatoes, rice, pasta
• Cellulose


  Important support material in plants
• Lipids


  Fats (solids) and oils (liquids), most efficient energy store in the body, important in cell membranes, hormones, and nervous system, insoluble in water
• Lipids


  • Made up of three molecules of fatty acids joined to a molecule of glycerol
• Lipid-rich foods


  • Oils, butter, margarine, cheese, cream
• Proteins


  Used for building up cells and tissues, basis of enzymes, 15-16% of body mass
• Proteins


  • Made up of long chains of amino acids, different arrangements of amino acids give different proteins, folded, coiled, and twisted into specific 3D shapes
• Amino acids


  Small units that make up proteins, joined together by special bonds
• Protein functions in the body include: structural components of tissues, hormones, antibodies, enzymes
• Testing for starch


  Add iodine solution - turns blue-black if starch is present
• Testing for sugars


  Add Benedict's solution, heat - turns brick red if sugars are present
• Testing for proteins


  Add Biuret reagent - turns purple if proteins are present
• Testing for lipids


  Add ethanol - gives a cloudy white layer if lipids are present
• Biuret solution is corrosive, wear chemical and splash-proof eye protection
• Simple sugars


  Related to complex carbohydrates as they are the building blocks
• Lipids can be either fats or oils depending on the combination of fatty acids