Microbiology Lab Report 5 pages

EXAMPLE OF REPORT

Title: Effect of Enzyme Concentration on the Reaction Rate (Urease Enzyme)

Introduction

Enzymes are molecules of proteins that facilitate a chemical reaction without losing its

chemical structure (Madder, 2009). An enzyme will sometimes break a substrate into

products once the substrate attaches to the active site, which is the place in the enzyme

that…

Sometimes the higher concentration of substrates in a solution can result in more

interactions with the enzymes as collations between molecules are more likely.

This experiment has the objective of evaluating the effect of the concentration of

enzymes on the chemical reaction target by the enzyme. Our hypothesis is that the more

enzymes present interacting with a specific substrate the more activity will result.

Materials and Procedure

The molecule of urea was selected as the substrate on which the enzyme urease acted

upon resulting in two products: carbon dioxide and ammonia. The presence of ammonia

was measured by determining the pH of the solution where the reaction took place.

Urea solution contained a pH indicator (Phenol Red) which shows a yellow color in acid

and a red color when the solution is basic.

Five test tubes were filled with 2 ml of urea solution containing the pH indicator. One test

tube labeled Control will not receive any of the treatment since it was used as a

comparison control.

Test tubes were labeled with the amount of drops of urease (enzyme) added. The amounts

of drops were: 15, 10, 5, and 1.

As soon as the drops were added to its corresponding test tube time was recorded until

the urease changed the color of the solution to red.

Once the last test tube was completed, the results were recorded in a table.

Results

The color change was reported as a qualitative observation since no apparatus was used

for this experiment. The fastest recording time was observed on the 15 drop (15 sec.) test

tube were as the longest time observed was with the 1 drop test tube (3 min.).

The results are presented in Table 1. A graph was prepared with the data presented in

Table 1.

Table 1. Effect of enzyme concentration on reaction rate.

Tube Label Volume of

Urea (ml)

Vol. of

Urease

(drops)

Reaction

time to Red

(sec.)

15 2 15 30

10 2 10 67

5 2 5 130

1 2 1 234

Control 2 No drops No change

Graph 1. Effect of Enzyme Concentration on Reaction Rate.

Conclusion and Discussion

The results of the experiment showed that as the amount of enzyme concentration is

higher, the time it took for the reaction to take place is smaller. Graph 1 shows an inverse

relationship between the concentration of the enzyme used and the time it took for the

chemical reaction to take place. This means the higher the concentration of enzyme the

faster the chemical reation will take. These findings are supported by another experiment

(Sattler et al., 1989) where cellulose was treated with different concentration of cellulase

enzyme showing that the hydrolysis reaction rate increases with increasing enzyme

dosage.

References

Madder, S. (2009). Essentials of Biology; 2nd Edition. McGraw Hill. New York, N.Y.

Sattler, W., Esterbauer, H., Glatter, O., Steiner, W. (1989). The effect of enzyme

concentration on the rate of the hydrolysis of cellulose. Biotechnology and

Bioengineering. Vol. 33, Issue 10, p. 1221-1234.

Butera, G. (2015) APA Citation Style, 6th Edition: APA. Himmelfarb Health Science

Library. Retrieved on March 2015 from: http://libguides.gwumc.edu/APA