The experiment was performed in order to observe the methods which can be used to demonstrate that proteins are present in different types of food.
Biological Investigation: Detection of Proteins
Introduction:
The experiment was performed in order to observe the methods which can be used to demonstrate that proteins are present in different types of food.
Research Question:
In what kind of foods are proteins present and what kind of techniques are used to prove the presence of proteins ?
Hypothesis:
If four samples of food,
- two of which are known to be rich in protein
- and two that lack in protein come into contact with three different substances, being:
- concentrated nitric acid (xanthoproteic reaction),
- potassium hydroxide and copper (II) sulfate, together with potassium sodium tartrate, also known as Biuret reagent , and
- ethanol, 89% alcohol by volume (process of denaturation),
then, the samples of ham and cheese will react to these substances, while lettuce and apple samples will not.
Hypothesis Explanation:
Ham and cheese are rich in protein,lettuce and apple are not.A xanthoproteic reaction will be produced when the samples which are rich in protein being combined with nitric acid.Its also called ''the xanthoproteic test'' in which a yellow acid substance is formed by the action of hot nitric acid on albuminous or proteid matter. It is changed to a deep orange-yellow color by the addition of ammonia.
In combination with biuret reagent,the blue reagent will turn into violet in case proteins are present.
Denaturation will appear when ethanol is added.Denatured proteins exhibit loss of solubility to communal aggregation.No change will occur if this substances are being combined with the low protein food apple or lettuce.
Compounds:
- apple
- swiss cheese
- iceberg lettuce
- plain ham
- concentrated nitric acid
- Biuret reagent
- ethanol (89%)
Variables:
- three reactant substances
- the reaction of the combined protein foods and the substances
Apparatus:
- lab apron
- gloves
- knife
- cutting board
- 12 test tubes
- test tube rack
Method:
1.Put on the apron
2.Cut the cheese,apple,lettuce and ham small enough that it fits into the test tube
3.Put the test tubes on a test table
4.Put the gloves on,take a test tube and fill a small amount of nitric acid into the tube
5.Observe what happens and write down your observations
6.Do the same with the other test tubes
7.Do the same again but this time use the biuret reagent and then the ethanol instead of nitric acid
8.Write down your final observations
Data Collection & Processing:
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Table 1: Reactions observed in the experiment.
Analysis & Conclusion:
Frequently Asked Questions about Biological Investigation: Detection of Proteins
What is the purpose of the experiment?
The experiment aims to observe methods used to demonstrate the presence of proteins in different types of food.
What is the research question?
The research question is: In what kind of foods are proteins present and what kind of techniques are used to prove the presence of proteins?
What is the hypothesis?
The hypothesis states that if samples of ham and cheese (known to be rich in protein) and lettuce and apple (lacking protein) are exposed to concentrated nitric acid, Biuret reagent, and ethanol, the ham and cheese will react, while the lettuce and apple will not.
What is the explanation of the hypothesis?
The hypothesis is based on the idea that ham and cheese contain protein, while lettuce and apple do not. Nitric acid will cause a xanthoproteic reaction with protein-rich samples, Biuret reagent will turn violet in the presence of proteins, and ethanol will cause denaturation in protein samples. No changes are expected in the low-protein foods.
What compounds are used in the experiment?
The compounds used are apple, swiss cheese, iceberg lettuce, plain ham, concentrated nitric acid, Biuret reagent, and ethanol (89%).
What are the variables in the experiment?
The variables include the three reactant substances (nitric acid, Biuret reagent, and ethanol) and the reaction of the combined protein foods and the substances.
What apparatus is used?
The apparatus includes a lab apron, gloves, knife, cutting board, 12 test tubes, and a test tube rack.
What is the method used in the experiment?
The method involves cutting the food samples into small pieces, placing them in test tubes, and then adding nitric acid, Biuret reagent, and ethanol to separate test tubes. Observations are recorded for each reaction.
What is the xanthoproteic reaction?
The xanthoproteic reaction is a test in which a yellow acid substance is formed by the action of hot nitric acid on albuminous or proteid matter. It is changed to a deep orange-yellow color by the addition of ammonia.
What is denaturation?
Denaturation is when proteins lose their solubility due to communal aggregation.
What were the conclusions of the experiment?
The conclusions stated that the results didn't perfectly align with the suggestions, but the xanthoproteic reaction proved the presence of proteins and was therefore successful. The experimenter suggested running another experiment with more efficient samples.
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- Quote paper
- Felix Dyrek (Author), 2008, In what kind of foods are proteins present and what kind of techniques are used to prove the presence of proteins?, Munich, GRIN Verlag, https://www.grin.com/document/159584
