Testing and Evaluating the Contents of Two Known Solutions for Proteins and Lipids

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Testing and Evaluating the Contents of Two Known Solutions for Proteins and Lipids Introduction For this experiment two solutions will be provided. In one test tube it contains milk and in the other test tube it contains sunflower oil. The test for proteins and lipids will be done for each solution and then a conclusion can be deduced from these results. To test for the proteins place 2cm³ of the test solution into a test tube and then add five drops of the Biuret solution to it. It is important to known what it is your looking for , in this case to show that there are proteins present it should develop a purple- violet colour, the intensity of which is proportional to the content of protein, with a high content of protein it will give a darker precipitate rather than if it had a low content where the precipitate will be lighter in colour. However if in doubt about the colour add more drops to it , wait a few moments a purple colour will develop if a protein is present. The reason why there is this colour change is because in because of the nitrogen atoms in the Biuret solution present in the peptide chain form a purple complex ( the nitrogen) with the Cu ²+ ions, it is the dilute copper sulphate that is in an alkaline solution. For the test for lipids I can use two tests. The first test being the translucence test where a drop of each solution is put on a piece of filter paper, if lipids is present than it should turn the filter paper translucent this because of the oils in the triglyceride chains causes this translucent effect on the filter paper. However if this test proves unsuccessful and not clear another test c... ... middle of paper ... ...oduce a green then to orange precipitate. The reason why this is because when the benedict's test was done for the non reducing sugar the lactose it at first had no effect, then the solutions would be neutralised and then dilute hydrochloric acid would be added to them. When lactose is heated with acid you hydrolyse it into the monosaccharide that it is made up of ( for lactose this is galactose and alpha glucose). So then when it is heated with the benedict's solution it gives you a reaction because now it can work as there are reducing sugars present that allow it to give red precipitate. The reason why test it would now go orange is because it contains non reducing sugars so when the non reducing sugar are heated it hydrolysed into twice as many monosaccharide- reducing sugars than there were of non reducing sugars.

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