An experiment to investigate the action of saliva on starch:

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Biology-SDH                by Rebecca Kriegbaum

An experiment to investigate the action of saliva on starch:

Research question

Do enzymes in our saliva break up starch into simple

sugars (mono- or disaccharides)?

 

Introduction

Enzymes are globular proteins, which act as biological catalysts.  They speed up reactions by binding to a substrate, such as for example the enzyme amylase, which binds to starch (a polysaccharide) in order to break it down into di- and monosaccharides. They are present in all organisms in thousand of different forms, most enzymes specific to only one substrate. An enzyme has an active site, at which it binds to a substrate, which is specific to its shape. An example for this is the enzyme amylase which catalyses the breakdown of starch, a polysaccharide for example found in potatoes. When it is digested by amylase, it will be broken down into disaccharides, which are sugars such as maltose. Then another enzyme, maltase, will break the disaccharide down into glucose, which is the monomer starch is made of.

Starch is a carbohydrate consisting of a large number of glucose units joined together. It is produced by all green plants as an energy store. It is the most important carbohydrate in the human diet and is for example contained in potatoes, wheat, maize (corn) and rice. Human saliva is rich in amylase, and the pancreas also secretes the enzyme.

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Iodine solution is used to test for starch; a dark blue colour indicates the presence of starch.

Hypothesis:

The longer starch and saliva are mixed, the more starch is broken down and the iodine will become brighter. As the solution is mixed with Benedict’s solution and heated in a water bath, it will change it’s colour, indicating that the starch in the solution has been broken down to reducing sugars by the amylase in the saliva.

  • The longer the amylase is reacting with the starch solution, the less starch will be present

    Therefore towards the end, ...

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