3.1

• Metabolism

  All the chemical reactions that take place in cells and therefore in the organism of which the cells are a part, concerned with maintaining a balance between energy release and energy utilisation
• Types of metabolism

  • Catabolic metabolism
  • Anabolic metabolism
• Catabolic metabolism

  The reactions in which large molecules are broken down to smaller ones, releases energy
• Anabolic metabolism

  The reaction in which small molecules are built up into larger ones, requires energy
• Nutrient

  Any substance in food that is used for growth, repair or maintaining the body, any substance required for metabolism
• Groups of nutrients

  • Water
  • Carbohydrates
  • Lipids
  • Proteins
  • Minerals
  • Vitamins
• Organic compounds

  Molecules that have a carbon chain, contain a number of hydrogen atoms and may include atoms of oxygen, nitrogen and sulfur
• Carbohydrates

  The main source of energy for cells
• Simple sugars

  Monosaccharides - glucose, fructose and galactose
• Formation of larger carbohydrate molecules

  1. Simple sugars join together to form disaccharides

  2. Disaccharides join together to form polysaccharides
• Lipids

  Include fats and oils, important source of energy
• Lipid molecule

  One molecule of glycerol and one or two or three fatty acid molecules
• Triglyceride

  The most common fat, composed of glycerol and three fatty acid molecules
• Proteins

  Organic compounds made up of many amino acids, the most important proteins made are enzymes
• Peptide bond

  Formed when two amino acids bond together, releases a water molecule
• Amino acids

  • Glycine
  • Alanine
  • Valine
  • Glutamic acid
• Dipeptides

  Two amino acids joined
• Polypeptides

  More than 10 amino acids joined
• Nucleic acids

  Include RNA and DNA
• DNA

  Two chains of nucleotides containing the sugar deoxyribose, stores inherited information
• RNA

  Single strand of nucleotides containing the sugar ribose, carries information from DNA to ribosomes for protein production
• Inorganic compounds

  Not based on a carbon chain, most do not contain carbon atoms, examples: water, minerals, vitamins
• Water

  Important as the fluid in which other substances are dissolved, some chemical reactions occur in water or use water molecules
• Minerals

  Important for metabolism as they may be part of enzymes, function as cofactors for enzymes, or be part of substances like ATP involved in metabolism
• Vitamins

  Act as coenzymes for many chemical reactions of metabolism