• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

Protein Digestion Design Lab. To detect the amount of protein molecules or short polypeptide chains in the cooked egg white for this experiment, the biuret reagent will be used.

Extracts from this document...


Protein Digestion Design Lab Introduction It is known that the chemical digestion of protein occurs in the stomach and small intestine. Proteins are polymers of monomers known as amino acids (a monomer is one unit of amino acid) aligned in a genetically determined sequence. Proteins contains the elements carbon, hydrogen, oxygen, nitrogen, phosphorus and sulphur. The amino acids in a polymer are joined together by the peptide bonds between the carboxyl and amino groups of adjacent amino acid residues. The sequence of amino acids in a protein is defined by the sequence of a gene, which is encoded in the genetic code. Like other biological macromolecules such as polysaccharides and nucleic acids, proteins are essential parts of organisms and participate in virtually every process within cells. Many proteins are enzymes that catalyze biochemical reactions and are vital to metabolism. An enzyme is a biological catalyst made up of protein. It alters the rate of a chemical reaction without itself being chemically changed at the end of the reaction. Variables that affect enzyme activity include temperature and pH. There is a particular optimum temperature and pH which allow enzymes to perform most efficiently. This implies that since the structure of the enzyme can be affected by temperature and pH, enzymes must be proteins. When the bonds which give a protein its unique shape are broken, the protein, in this case an enzyme, is denatured. ...read more.


Incubator 12. Electronic scale 13. 10 ml granulated cylinders 14. Stir rods 15. Scoopulas 16. Eye droppers 17. Scalpels, 18. Biuret reagent 19. Hot plates 20. Distilled water Method 1. Wash all the test tubes thoroughly 2. Cut the egg white into 8 equal pieces of 3-5mm in length 3. Put each piece of egg white into each of the 9 test tubes, number the test tubes A through B. 4. Test the egg white samples in the test tubes by adding the following substances: Test tube A - 5ml of distilled water Test tube B - 5ml of distilled water and 1ml of 0.01M sodium hydroxide Test tube C - 5ml of distilled water and 1ml of 0.01M hydrochloric acid Test tube D - 5ml of pepsin solution Test tube E - 5ml of pepsin solution and 1ml of 0.01M sodium hydroxide Test tube F - 5ml of pepsin solution and 1ml of 0.01M hydrochloric acid Test tube G - 5ml of pancreatin solution Test tube H - 5ml of pancreatin solution and 1ml of 0.01M sodium hydroxide Test tube I - 5ml of pancreatin solution and 1ml of 0.01M hydrochloric acid 5. Test the pH level of the solutions in all of the test tubes. Record this. 6. Set the test tubes for 24hrs in the incubator with the temperature set to 37oC. 7. Add the biuret reagent to each of the test tube mixtures one drop at a time, shaking the mixtures gently in between each drop. ...read more.


Test tube D contained only the pepsin solution, and without the acidic environment to activate the enzymes, hence no protein digestion took place. Test tube E contained the pepsin solution and the 0.01M sodium hydroxide, and the alkaline mixture prevent the enzymes from being activated to digest the proteins, so no protein digestion took place either. Test tubes G and I also did not show any results of protein digestion, as they did not contain the required chemicals to create an optimum environment for the enzyme trypsin in the small intestine. Test tube G contained only the pancreatin solution, and the enzymes would not be able to digest the proteins in a non-alkaline environment. Test tube I contained the pancreatin solution and the 0.1M hydrochloric acid, and the acidic environment prevented the enzymes from being activated to digest the proteins, so there was no protein digestion here too. In conclusion, the optimal conditions for protein digestion in the stomach would be an acidic environment of pH 2; the optimal conditions for protein digestion in the small intestine would be an alkaline environment of pH 8. Limitations of the experiment: 1. Only 1 of each trial was done 2. The experiment was based on largely quantitative results, such as based on observation of the egg white to see how much was digested, or the colour change of the biuret reagent(which can be unclear if too much reagent is added) ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our International Baccalaureate Biology section.

Found what you're looking for?

  • Start learning 29% faster today
  • 150,000+ documents available
  • Just £6.99 a month

Not the one? Search for your essay title...
  • Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

See related essaysSee related essays

Related International Baccalaureate Biology essays

  1. Plant Tropism Lab

    data shows that the beans generally increase their tilt to the right, where the light source is. This shows that plants grow towards a light source, which in this case would be the sunlight. The data also shows that when the beans were rotated 90 degrees counter clockwise (to the left)

  2. Vitamin C Lab

    may have an error bar compared to the other temperatures could be Kenneth and I were unfamiliar with which point the lemon juice decolourised, and we did our first titrations at room temperature. This leads to one important aspect regarding the reliability of our data - the determination of the end of point the titration.

  1. Investigating the effect of pH of Hydrogen Peroxide upon the activity of Catalase

    Furthermore, my graph showing the optimum pH level for the Catalase enzyme shows the relationship between the pH levels and the mean rate of reaction; as the level of pH increases (my independent variable) the rate of reaction (my dependent variable)

  2. Digestion Lab. The specific purpose of this lab (activity 4) was to investigate fat ...

    A solution containing fatty acids liberated from fat will exhibit a lower pH than one without fatty acids (2). Results: Pancreatic Lipase Digestion of Fats and the Action of Bile Tube no.

  1. investigating the action of pepsin on egg white

    We know that enzymes are proteins that catalyze a reaction by lowering the activation energy. The substrate used in this experiment consists of the egg white(albumen).It has been heated in order to solidify it, thus denaturizing it ,permanently damaging its protein structure and it has also been finally divided and suspended in water to form an opaque white liquid.

  2. Osmosis Experiment. This experiment is to consider how salinity influences osmosis in potato cells.

    coat around the whole piece of potato 0.6% Marble-white, a few brown dots The whole solution looks cloudy Feels a bit mushy but not slippery Hard to see if there is a fur-like coating because the colour of the potato and solution appear similar.

  1. Identification of Carbohydrates ,Lipids,and Proteins lab

    Chicken Bouillon Clear Blue Distilled Water Clear Layer of blue on top Investigation 4: Identification of Proteins ? b) Xanthoproteic Test Materials Colour before adding HNO3 Colour after adding HNO3 10% egg albumin Clear Murky white 1% Gelatin Clear clear Milk White Precipitate forms Chicken Bouillon Clear Murky Distilled Water Clear Clear Analysis Investigation 2: Identification of Carbohydrates ? a)

  2. How does cooking affect the amount of vitamin C in lemon juice?

    According to international data standard (July 1980), the mass of ascorbic acid equivalent to 1 cm3 of DCPIP is 0.05 mg. This means that the volume of lemon juice sample titrated to decolourise DCPIP contains 0.05 mg of ascorbic acid.

  • Over 160,000 pieces
    of student written work
  • Annotated by
    experienced teachers
  • Ideas and feedback to
    improve your own work