enzymes

• enzymes are biological catalysts - speed up reactions without being used up themselves
• enzymes are proteins - made up of amino acids
• enzyme have active site - work with specific substrate (form enzyme substrate complex)
• substrates bind to the active site, forming an ES complex
• the shape of the active site is complementary to that of the substrate
• enzyme could break down or bind molecules
• after optimum temperature - active site denatured, enzyme is inactive
• optimum pH = when most enzymes are active
• pH too high/low = enzyme becomes denatured
• when temperature increase - molecule increase of kinetic energy, more collision
• optimum pH for stomach - pH3
• optimum pH for small intestine - pH9
• denatured - the change of shape of the active site that doesn't allow substrate to fit anymore due to high temperature
• independent variable - pH of buffer
• dependent variable - time taken for the starch to be fully broken down
• control variable - temperature, concentrated enzyme, concentrated substrate, time, volume
• step 1 - using water bath at 37 degree (optimum temperature)
• step 2 - measure 5 ml of amylase, 5 ml of pH buffer, 5 ml of starch (in separate cylinders)
• step 3 - leave the cylinders in the water bath for 10 mins - adjust to the temperature
• step 4 - place a few drops of iodine into each well of a spotting tile
• step 5 - Mix buffer, amylase and starch together and keep it in the water bath (15 ml mixture)
• step 6 - Add a drop of the mixture into one of the wells with iodine every 30 secs
• step 7 - time how long it takes for the starch to be fully broken down (stop turning blue/black)
• step 8 - repeat for a range of buffer
• carbohydrate break down into sugar
• iodine is used to test starch
• positive result for starch - yellow to black
• positive result for sugar - blue to green/yellow/red
• Benedict's solution is to test sugar
• carbohydrate is energy source in respiration
• protein is used for growth, repair
• protein break down into amino acids
• biuret reagent is used to test protein
• positive test result for protein - blue to purple
• fatty acid + glycerol = lipid
• ethanol is used to test lipids
• positive test result for lipid is turn cloudy, white emulation, and a white precipitate
• Digestion - the breakdown of large insoluble molecules into smaller soluble molecules that can be absorbed into the blood. It is sped up by enzymes.
• salivary glands produce amylase - carbonhydrase
• oesophagus transfer food into stomach