Investigating Digestive Enzymes

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Using Visking Tubing to Model the Gut

  • Visking tubing is a good model for the gut. It lets small molecules through but not big ones. It is cheaper, easier and less yuky than an animals gut.
  • Our guts are longer and have a massive surface area. It means the speed of digestion and absorption wil be sligtly different. 
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Use Iondine to Test for Starch and Benedicts to Te

  • Add the same volume of starch suspension and 0.25% amylase solution to the visking tubing.
  • Rinse the outside of tubing and put in to distilled water.
  • Straight war test a drop of water from around the tubing with iodine soultion with Benedicts reagent and record coulour.
  • Test the water again after 15 minutes and record the colour each time.
  • Repeat the experiment using other concentrations of amylasse solution.

Orangey-brown colour means theres no starch in water due to the starch molecules being too big to pass through the visking tube.

Brick-red shows theres sugar in the warer because starch as been broken down by amylase to sugar and the molecules are smaller enough to pass through membrane in to water.

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Enzyme Concentraion Affects the Rate of Reaction

  • The higher the concentration of amalayse, the faster the rate of reaction
  • This is bigger because the more amalayse there is, the faster it breaks doen the starch
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