Biology Lactase Lab Report Example Essay

1384 Words Oct 31st, 2013 6 Pages
ABSTRACT: Two separate variables were hypothesized and tested within the confines of the experiment on their effects on the productivity of lactase enzyme. The measurement of light absorbance levels of different solutions based on both the concentration of o-nitrophenol (ONP) as well as the pH of the solution tested. To begin with, differing concentrations of ONP were tested to find the absorbance levels of ONP. Three different pH values, 5, 6, and 7, in solution, were tested over a period of 8 minutes and their absorbance’s recorded. Both plots of data were then used to find at which concentrations of ONP absorption levels, and thus enzyme activity rates, were at their highest across each of the three pH solutions. Based on the results …show more content…
It was hypothesized that as concentration of enzyme precipitate in the form of ONP was increased so would the absorption levels. It was also hypothesized that if the lactase enzyme reaction took place at a pH of 5 it would have the highest absorbance level as reactions with other pH levels would change the enzyme’s shape and thus decrease overall absorbance (Fankhauser).

Absorbance levels of a 40% ONP concentration in 5 mL were measured at wavelengths ranging from 400-600 nm by 20 nm intervals to find the optimal wavelength for testing. Absorbance levels of a pH 5 buffer and ONP solution were measured at amounts of ONP ranging from 0 to .40 μ mol. A blank was made containing 20% lactase enzyme in 5 mL. In a small beaker 15 mL of pH 5 buffer and 6 mL of enzyme were mixed. To each of 5 cuvettes, initially 1 mL of Na2CO3 was added. As soon as 3 mL of ONPG was added to the small beaker, creating a 0.05 μ mole concentration of ONP, a timer was started and 4 mL of solution was added to the cuvette labeled 0. Four mL of solution was transported from the beaker to each of the 4 remaining cuvettes at the appropriate times of 2, 4, 6, and 8 minutes. After the final 8 minute cuvette was filled the absorbance levels of each cuvette were measured at 415 nm. This experiment was completed 3 times and then repeated 3 times again using both a pH 6 and 7 buffer.

Figure 1 shows the changes in the absorbance level as the

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