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Test and evaluate the contents of two known solutions for proteins and lipids

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Introduction

Title -to test and evaluate 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 2cm� 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) ...read more.

Middle

A cloudy white suspension was formed, opaque colour The solution split in two with a blue clear solution at the bottom and a gel like cloudy solution at the top. Conclusion From my results I could deduce whether or not protein or lipids were present in each of the solutions. For the milk I came to the conclusion that there was both lipids and protein that was present in it. The reason why this was so , was because I knew that protein was present because it in the Biuret solution test turned a cloudy purple precipitate colour which indicated to me that protein was present in the milk. 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 �+ ions, it is the dilute copper sulphate that is in an alkaline solution. For the milk as well as there being protein present there was also lipids that were present. The reason why I know this to be the case is because when the emulsion test was done on it , produced a cloudy white suspension which indicated to me that lipids were present in milk, the reason why this is because lipids are immiscible when they are in water. ...read more.

Conclusion

The results for using a Benedict's test in milk is that , milk contains the disaccharide lactose which , like fats provides energy. Lactose is also used within the infants body to make the monosaccharide galactose. Lactose is a disaccharide therefore it is a non reducing sugar when the benedict's test is firstly done on it will have no effect first of all , however when the solution is then boiled in acid and then Benedict's is tested on it will produce 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 Zaynab Araim biology 12.9 ...read more.

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