Amylase Starch Experiments

Amylase is an enzyme responsible for converting starches into the sugar maltose, which is a disaccharide. This enzyme, present in saliva, is a key component in germinating plants. The starches contained within the seed are converted to sugars, providing energy to the plant before photosynthesis begins. Experiments with amylase demonstrate how the enzyme reacts with starches and variables, which affect the rate of the reaction.

Bread is full of carbohydrates. Starches are considered a type of complex carbohydrate, which begins to be broken down into maltose as soon as it's in our mouths. Give each student a slice of bread that has been cut in two. The students chew one half of the bread for three minutes and write down their observations as to the changes in how the bread tastes. The other half of the bread is chewed for 10 seconds, then placed in a safe container for 10 minutes. After 10 minutes are up, the students chew the bread again. In both cases, the bread should begin to get sweeter as the amylase begins to convert the carbohydrates into maltose, which tastes sweet.

Give the students three corn seeds — one dry, another that has been boiled, and one that has been soaked in water. The students cut the seeds in half and place the seeds on an agar petri dish that has a starch solution. The students then incubate the seeds for 30 minutes. After removal, they add an iodine solution over the plates. Starches remaining on the plate react with the iodine, creating purple areas. Students observe the differences between the seeds to determine which type of seed had more active amounts of amylase present.

As with all enzymes, amylase has a preferred pH level in which it operates. This can be determined by creating different pH levels and amylase reactions that measure the speed of the reaction. Place iodine solution drops in a test tube. In test tubes mix amylase, starch and a buffer solution with different pH levels. After mixing the solution, remove a small amount using a pipette and add it to the iodine. The iodine must turn orange when the reaction is complete. The students test the solution every 10 seconds until they arrive at the correct color. The experiment is repeated at each pH level. The pH level that turned orange the fastest is the preferred pH of amylase.

Amylase reactions happen more rapidly at certain temperatures. Place iodine solution in a tray. Mix the amylase, starch and buffer, use the same pH this time, and test how long it takes to turn orange. Raise the temperature of the solution by 10 degrees for the next solution and retest the time it takes for the reaction to test. Students should determine the optimum temperature for the amylase reaction through multiple trials.