benches, small beaker or other container for collecting saliva, Benedict's solution, water bath at 70 °C, additional syringe or pipette. B1f Enzyme B1.7 Explain the mechanism of 1) Explain that an egg Students investigate the effect Demonstrate that action enzyme action including the white is made up of of temperature on the time enzymes are specific to active site and enzyme proteins. Boil an egg taken for amylase to digest particular substrates by specificity white in a boiling tube. starch. testing a range of Remove the solidified enzymes on a range of white from the tube with substrates. This could Explain how enzymes can be The length of time for the B1.8 a spatula. Remind be done by using the denatured due to changes in reaction to reach completion students that enzymes separate enzymes found the shape of the active site (as indicated by the iodine are proteins, and ask solution remaining yellow) in laundry detergents them to suggest how (available from the should change with enzymes might be temperature. NCBE) on a range of affected by heat. clothes 'stains' made Equipment: For each with a particular temperature tested: test tube substrate (e.g. cooking Equipment: Fresh egg, containing 5 cm3 1% starch oil (lipid), egg white boiling tube, boiling suspension, test tube water bath , tongs, (protein), ketchup containing 1 cm3 1% amylase (carbohydrate)) on a spatula. solution (or 0.5% pancreatin piece of clean old cotton solution) or saliva collected fabric such as sheeting. 2) Students work in by student, water bath at groups to write a 'story' appropriate temperature, 5 that will describe the role Equipment: cloths of cm3 syringe or pipette, old white sheeting or of enzymes in digestion, beaker of water for washing similar, stained with a such as 'Enzymes are pipette, eye protection, iodine range of substrates that essential for the digestion solution, well tray (spotting contain only one kind of of food.' tile).
benches, small beaker or other container for collecting saliva, Benedict's solution, water bath at 70 °C, additional syringe or pipette. B1f Enzyme action B1.7 B1.8 Explain the mechanism of enzyme action including the active site and enzyme specificity Explain how enzymes can be denatured due to changes in the shape of the active site 1) Explain that an egg white is made up of proteins. Boil an egg white in a boiling tube. Remove the solidified white from the tube with a spatula. Remind students that enzymes are proteins, and ask them to suggest how enzymes might be affected by heat. Equipment: Fresh egg, boiling tube, boiling water bath , tongs, spatula. 2) Students work in groups to write a 'story' that will describe the role of enzymes in digestion, such as 'Enzymes are essential for the digestion of food.' Students investigate the effect of temperature on the time taken for amylase to digest starch. The length of time for the reaction to reach completion (as indicated by the iodine solution remaining yellow) should change with temperature. Equipment: For each temperature tested: test tube containing 5 cm3 1% starch suspension, test tube containing 1 cm3 1% amylase solution (or 0.5% pancreatin solution) or saliva collected by student, water bath at appropriate temperature, 5 cm3 syringe or pipette, beaker of water for washing pipette, eye protection, iodine solution, well tray (spotting tile). Demonstrate that enzymes are specific to particular substrates by testing a range of enzymes on a range of substrates. This could be done by using the separate enzymes found in laundry detergents (available from the NCBE) on a range of clothes 'stains' made with a particular substrate (e.g. cooking oil (lipid), egg white (protein), ketchup (carbohydrate)) on a piece of clean old cotton fabric such as sheeting. Equipment: cloths of old white sheeting or similar, stained with a range of substrates that contain only one kind of
GCSE-Science-Term-1-Detailed-Planning-Document.docx