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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