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Introduction

Investigating the action of pepsin on egg white Data Collection: The following table shows the lengths of egg white in a number of tubes before and after boiling: Contents The length before boiling(cm) The length after boiling(cm) Tube 1 HCL+Water 5.2 5.2 Tube 2 Pepsin+Water 4.7 4.7 Tube 3 HCL+Pepsin 5.5 5.2 Tube 4 HCL+Water+boiled Pepsin 4.9 4.9 Tube 5 Water 5.2 5.2 Table (1) Conclusion and Evaluation: While the food is in the stomach, it is mixed with acid, and enzymes, so chemical digestion takes place. During this, the peristaltic movements on the muscles in the wall of the stomach will mix the food until it is almost a fluid while is called chyme. ...read more.

Middle

The enzyme pepsin is from a mammalian digestive system. Depending on the conditions in the surrounding medium, it may break down (digest) the egg white to different extents, thus clearing the liquid. All proteins, including those in egg white, are made of long chains of amino acids, which are similar to beads on a string. In a raw egg, these strings are raveled up in a tangled compact mass. Chemical bonds and interactions between the amino acids within each protein hold this mass in a specific shape and stop it from unraveling. Heat causes the bonds within the proteins to break, a process called denaturation. ...read more.

Conclusion

Test tube (1) does not contain an enzyme, it contains (HCL+Water only) so no reaction will occur. 2. Test tube (2) contains pepsin, but without the acid HCL, that causes the decrease in PH to become 2-3 that is the optimum for pepsin. 3. Test tube (4) contains HCL+Water+boiled Pepsin, which means that the pepsin is denaturized. 4. Test tube (5) contains only water that does not affect proteins. Sources of error: In the instruction sheet, it is written that we must leave the test in the boiling water for 30min, but we did not because we hadn't enough time. In addition, we were inaccurate in measuring the lengths of egg white. Improvements: We must leave the test in the boiling water for 30 min, and measure the lengths of egg white more accurate. ...read more.

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