The Hydrolysis of Starch through the use of Salivary Amylase, and the Phosphorolysis and Synthesis of Starch through the use of Phosphorylase

Name: Thien Nguyen

ID: 20299974

Partner: Robert Taylor

TA: Ravil Dhillon & Saahil Vij

BIOL 130L – 002

B2 – Biology 2 149

Monday 7:00PM-9:50PM

Monday November 2nd 2009

Introduction

Within a cell there are many reactions going on at the same time and a cell cannot process these reactions without the help of enzymes, a biological catalyst.  Although all enzymes are catalysts, not all catalysts are enzymes, this is because of the enzyme’s specificity to what it acts on, and this is determined by the sequence and amount of amino acids, and also by the 3 dimensional forms that it takes.  This makes the enzyme only act for very specific and closely related reactions.  The reactant, called the substrate binds to the enzyme’s active site, however it will only bind if the substrate fits, and this forms a substrate-enzyme complex.  By doing this, the activation energies for the reaction to take place are lowered so that the reaction can be accelerated (Department of Biology, 2009).

There are two parts in the experiment, the hydrolysis of starch with amylase, and the phosphorolysis and synthesis of starch using phosphorylase.  In this lab, the purpose is to investigate the substrate concentration, reaction time, and enzyme concentration to determine if these factors will affect the direction of an enzyme reaction. To determine this, we will be using the iodine and Benedict’s test in several different situations and also at fixed intervals.  The iodine tests for starch, and it turns blue/black in the presence of starch.  The iodine test is done by adding a drop of iodine into a small sample of what needs to be tested.  In the Benedict’s solution test, it tests reducing sugars such as glucose.  The Benedict’s test is done by adding a small amount of Benedict’s solution is added to the sample and then place it into a boiling water bath, if the blue solution of the Benedict’s test produces a coloured precipitate (yellow or green to red, or brown), then the test is positive for the detection of a reducing sugar (Department of Biology, 2009).

Materials and Methods

The experimental procedure used for this experiment was outlined in: Department of Biology 2009 Cell Biology Laboratory Manual.  University of Waterloo, Waterloo. pp. 38-43.  Note: in step 11 of the phosphorylase section of the lab, instead of testing for 30 minutes, it was lowered to 20 minutes of testing (Department of Biology, 2009).

Results and Observations

Table 1.  Results of the iodine and Benedict’s solution test of test tubes 1 - 5

This table shows the qualitative results for each test.  Blue/black for iodine test indicates that the iodine test for starch is positive and a coloured precipitate (ranging from green to red or brown) for the Benedict’s test indicates a positive result for reducing sugars.

Table 2. Results of the iodine test for test tubes 11-15

Join now!

The table above shows the qualitative results from each iodine test trial at varying enzyme concentration.  It also shows the intervals (in seconds) in which the results were recorded.  

Table 3.  Results for the Benedict’s solution test for test tubes 16-20

This table shows the qualitative results from the Benedict’s test for each of the test tubes (16-20) after the end-point was reached for the solutions.            

Graph 1.  Time required to reach end-point VS salivary amylase concentration graph

The graph above shows the relationship between the different salivary amylase concentrations ...

This is a preview of the whole essay