Biuret Test Lab Report

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Biuret test is a test which is utilized to indicate unhydrolyzed proteins. When there are peptides in a solution, a copper (II) ion forms violet-coloured coordination complexes in an alkaline solution. The biuret test can be utilised to analyse the concentration of proteins due to peptide bonds that occur with the same frequency per amino acid inside the peptide. In this experiment, the colour changed to purple to indicate the presence of protein. The pH was found to be 7, which is in the range of a healthy person’s pH (which is 7.4).Benedict`s solution is made up of alkaline copper sulphate and sodium citrate (blue in colour) (Danson and et al, 1996).

When it is put in a hot water bath (boiled) when there are reduced sugars, cupric ion is decreased by sugars changing it into an insoluble red cuprous oxide. The solution will change to yellow, orange, green or red, for rising levels of sugar, and will stay blue if no sugar is detected. If the solutions stay the same (blue), the result is negative. In this experiment, the colour remained blue and thus there were no sugars present in the solution. The starch was not broken down into sugars. Salivary amylase was utilised to study how alterations in concentration of this enzyme affect the rate of reaction with starch. Salivary amylase is
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Starch continues showing blue colour with iodine until it is completely digested into maltose. At this point, the solution changes to colourless solution. The reason why the effect on temperature test was conducted was to determine the temperature at which the amylase works best at digesting starch. The theory of this test states that if amylase left at 37◦C, then the amylase will work best at digesting starch than at any other temperature. This temperature at which the amylase functions best is known as the optimal temperature (Cope,

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