Internal Assessment – Investigating the Relationship between Concentration of Sodium Chloride and the Rate of Reaction of Enzyme Amylase
Research Question:
How will changing the percentage of sodium chloride concentration affect the rate of reaction of enzyme amylase, measured using the absorbance of starch and iodine with a spectrophotometer.
Introduction:
Amylase is an enzyme that is involved in the human digestive process. Found in both the human pancreas and the human saliva, amylase breaks down starch into sugar so that large molecules can be easily digested1. Like all enzymes, amylase must be kept in a certain condition in order to function properly. In this experiment, the effect of sodium chloride concentration on the rate of reaction of amylase will be investigated with the use of starch and iodine. When starch is mixed with iodine, the coils of beta amylose molecules found in starch trap iodine, causing the mixture to turn into a shade of blue-black. 2 When starch is broken down into glucose, however, the monosaccharide does not react with iodine. Therefore, glucose does not change color even when it’s mixed with iodine. Correspondingly, when drops of amylase are inputted into a blueblack mixture of starch and iodine, the starch molecules will be broken down into glucose molecules, causing the mixture to turn colorless. Thus, the rate of reaction of amylase correlates to the absolute value of the rate of change in absorbance of the solution. A rapid decrease in the absorbance of the blue-black color equates to a high rate of reaction of amylase, whereas a slow decrease in absorbance signifies a low rate of reaction. In this experiment, an external variable of sodium chloride will be manipulated into the amylase enzyme to determine the effect the concentration of sodium chloride on the rate of reaction of amylase. Rate of Reaction = │ │
1
"Amylase." Wikipedia. N.p., n.d. Web. 12 Jan 2011. .
2
Senese,