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An Investigation to Determine the Lowest Concentration of Copper Sulphate that Brings Full Denaturation of Egg  Albumen.

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Introduction

An Investigation to Determine the Lowest Concentration of Copper Sulphate that Brings Full Denaturation of Egg Albumen Centre 15131 Candidate 4455 Aim: The aim of this experiment was to see at what concentration the egg albumen would be fully denaturated by the copper (II) sulphate at room temperature, so we had to determine the lowest concentration of copper sulphate that gave full denaturation. Background Information: The egg albumen is the globular protein in this experiment and the copper (II) sulphate is the solution that denatures the protein. Denaturation happens when the peptide bond in the protein is broken by hydrolysis, which is caused by the copper (II) sulphate. Proteins are made from the same basic component that are amino acids. The reason proteins differ is because of the amino acid and the amino acids differ because of the R group, which they contain. There are 20 different amino acids that occur in proteins. The R groups are responsible for the 3D shapes of protein molecules and functions. Also the fact that it is a heavy metal e.g. copper it means that it reduces the protein charge and affect the protein structure and this effect causes the precipitation of the protein (Advanced Bio-Student Revision manual). N C C (Biology 1 OCR in Biological molecules) ...read more.

Middle

sulphate was added, it went very viscose. The main problem was getting the precise amount of egg albumen, because it was so thick that the syringe found it hard to take up. Also I stirred both mixtures before using them so they stayed in suspension. Prediction I predicted that as the concentration of copper (II) sulphate was decreased the amount transmission (%) would increase in the colorimeter. I predicted this would happen, because as the concentration decreases of the copper (II) sulphate then the rate of reaction will decrease and so the peptide bond which, were broken by the copper (II) sulphate at a higher concentration will not be broken because they will resist and the reduced copper (II) sulphate concentration will mean less distorted shape and charge of the molecule. Also from my preliminary work, I found that when the molar was decreased to 0.04molar I then got an increase in the transmission percentage. Percentage transmission Concentration Experimental Plan: After the preliminary experiment, I concluded that the best amounts were 2ml of egg albumen and 1ml of copper (II) sulphate. To make the experiment more accurate I shall do a repeat to get reliable results and I will then take an average to get reliable and accurate results and the measurements for the percentage of transmission will be to 2-sig fig and the concentration will be to 2 decimal places. ...read more.

Conclusion

sulphate (moles) Graph From this graph we can see that all the way to the concentration of 0.05 there is still full denaturation, but at 0.04 the amount absorbed it now 3%. This shows that the lowest concentration that brings around full denaturation of egg albumen is between 0.05 and 0.04. Also the graph shows that passed 0.04 the amount of transmission % increases until we get to 0 where the transmission % is 100. How did I make it a Fair Test? The variables that I had to deal with were temperature and pH and egg albumen. First I had to deal with the temperature. The temperature of the room stayed the same, so this meant that it was controlled at 21?C. If the temperature was changing then I could have used a water bath at 21?C. Secondly, I would control pH by using a buffer to stop the pH from changing if a pH change was noticed. Thirdly, I used the same egg albumen all the way through because if I had changed it and had a different batch it may have caused anomalous results. Also I stirred the albumen before using it so it was in suspension. Fourthly, I did vary the concentration and I did 7 different concentrations to determine where the lowest concentration was where denaturation happened fully. I also did a control with a concentration of 0 to see if with no copper (II) sulphate there would be denaturation. ...read more.

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