M 3.1 Since then, more enzymes have been extracted from bacteria, yeasts and other sources and added to washing powders. Many of these are proteases, which can break down stains such as blood, egg, and gravy. Others remove starch stains, and fats and grease. When the enzyme cellulase is added to the washing powder, the microfibrils of cotton are broken down, which brightens the colour of washed clothes. All these enzymes work at temperatures below 40 °C. Soon designer enzymes with improved performance could be made. These genetically engineered enzymes would have their amino acid sequence altered to change the shape of the active site. This would result in enzymes with new and improved properties. (Dawson, Holm, Jackson, & Skinner, 2008) 3.2 3.3 3.4 Question 3 Read the extract on biological washing powders and answer the questions that follow. Biological washing powders contain enzymes that break down stains and dirt in fabrics. The first protein-digesting enzyme was discovered and used as long ago as 1913. The enzyme was obtained from the pancreases of animals. It was not very effective since it was not very stable and was easily broken down when detergent was used. In the 1960s a far more useful enzyme was extracted from a bacterium called Bacillus subtilis. The enzyme is stable in a detergent medium. The enzyme could also function in temperatures up to 60 °C, a high pH, and in the presence of phosphates and other chemicals in washing powder. What is the substrate of proteases? Explain how the Lock-and-Key model of enzyme action works. Washing powders containing enzymes work well at 40 °C. Suggest two important advantages of this. What are the advantages of using microorganisms such as bacteria to produce enzymes? (1) (3) (2) (2) 3.5 Enzymes are temperature and pH sensitive. What would happen to the enzymes in the washing powder at extreme pH levels? (2) (10)​