The effect of enzyme concentration on enzyme activity.

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Daniel Abdelmassih                Page  of

Core practical – the effect of enzymes

        

The effect of enzyme concentration on enzyme activity

Introduction

        This experiment relates significantly to the pancreatic duct because in cystic fibrosis suffers this can become blocked by mucus. The pancreas has an exocrine function by producing digestive enzymes. These go through the pancreatic duct to the small intestine where food is digested, however this release of enzymes is prevented or restricted as a result of the duct being blocked. This means that less enzyme concentration is released so digestion is not as good.

        In this experiment I will be adding distilled water to the enzyme to make protease to make different enzyme concentrations. Then adding these separate concentrations to a milk powder solution containing the substrate protein casein and timing how long it takes each solution to clear.

Hypothesis

        The substrate solution will clear quicker with a higher enzyme concentration. Enzymes are a type of globular protein which acts as a biological catalyst. They have poly-peptide chains folded into a compact spherical shape which keeps its structure by bonding between amino acids. The structure makes a three dimentional shape which is vital in catalysing reactions within cells and forming the enzyme-substrate complexes. A depression on the three dimentional shaped surface of the molecule is the active site. This takes up only a fractional of the enzyme molecule so only a few of the amino acids will be directly involved in the active sites. Substrate molecules are either single or more complementary molecules that fit into the active sites.

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These form tempary bonds with the amino acids forming an enzyme – substrate complex.  During each separate reaction products are formed which are released and enzyme concentration remains the same.  The enzyme works only for a specific reation due to its uniquely shaped active site.  Once the substrate is in the active site the molecule changes shape around the substrate.  Energy is needed in the reation to start it and to break chemical bonds to convert the substrate into products; this energy is called the activation energy.  

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This is fair attempt at writing up an investigation into the effect of enzyme activity on reaction rate using the action of protease on milk protein. The writer has a reasonable grasp of the theory behind the practical. He/she addresses most of the key areas which make up good scientific practice. However, the report would have benefited greatly from the following improvements: [1] A detailed introduction to the biochemistry of enzyme concentration and reaction rates; [2] More careful use of the terms 'accurate', 'reliable' and 'precise'. [3] A more thorough treatment of controlled variables where specific levels of each variable were stated; [4] A detailed risk assessment in standard format (risk/risk management); [5] A more detailed analysis of results discussed in the light of work carried out by other biologists. Many of these points are common areas of weakness in GCSE and A'Level reports and this particular essay is therefore a useful learning tool.