metabolism

• metabolism: the chemical processes that occur within a living organism in order to maintain life
• in a cell, there are many chemical reactions happening at all times, which are controlled by enzymes
• many small glucose molecules are joined together to form starch, glycogen and cellulose
• lipids molecules are each made from one molecule of glycerol and three fatty acids
• glucose is combined with nitrate ions to make amino acids, which are then made into proteins
• protein is broken down in the body to produce urea, which is then excreted in urine