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1 . 3 N U T R I T I O N The Function of Food: Growth, Repair, Energy ELEMENTS IN FOOD: WATER Bimolecular units: The elements in food combine in different ratios to form different food components Common Elements: Carbon (C) , Hydrogen (H) ,Oxygen (O), Nitrogen (N), Phosphorus (P), Sulphur (S) Salts of: Sodium (Na), Magnesium (Mg), Chlorine (Cl), Potassium (K), Calcium (Ca) Trace elements : Iron (Fe), Copper (Cu), Zinc (Zn) Properties of water: • Gives cells their shape • Transports materials • A universal solvent • A medium for metabolism CARBOHYDRATES Contain elements: C, O, H. General formula: Cx(H2O)y Structural role: cellulose forms part of the cell wall Metabolic role Source of energy for metabolism Types of Carbohydrate Monosaccharides e.g. glucose Disaccharides e.g. sucrose Polysaccharides e.g. cellulose MINERALS Plants need Magnesium to make chlorophyll and calcium for the cell walls Animals need iron to make haemoglobin and calcium for healthy bones. ENERGY TRANSFER REACTION FATS Contain elements: C, O, H. Different ratio to carbohydrates – have more oxygen Fats are solid at room temperature Oils are liquid at room temperature Structural role: protect the body organs Metabolic role Source of energy for metabolism Triglycerides: made up of three Fatty acids and one Glycerol Phospholipids formed when one fatty acid of a lipid molecule is replaced by a phosphate group Anabolic reactions: Small molecules are built up into large ones, using energy e.g. photosynthesis Catabolic reactions: large molecules are broken down into smaller ones, energy is released e.g. respiration PROTEINS Contain elements: C, O, H, N They sometimes contain P, S They are made up of amino acids Structural role: they join with phospholipids to form the cell membrane Metabolic role: all enzymes are proteins and they control the cells chemical reactions VITAMINS Vitamin Type Source Function Deficiency C Water soluble Lemons Connective tissue formation Scurvy D Fat soluble Cod-liver oil Absorb calcium Rickets