Investigating the effect of pH on the hydrolysis of starch by alpha amylase.

Authors Avatar

Investigating the effect of pH on the hydrolysis of starch by alpha amylase

Planning a:

Research question:

The aim of this experiment is to investigate the effect of pH on the hydrolysis of starch by alpha-amylase.

Hypothesis:

Starch is broken down by en enzyme, the enzyme amylase. Enzymes are defined as biological catalysts, which speed up a reaction and make it more likely to happen. They are very specific for each reaction they catalyse, which is called enzyme specificity.

Every enzyme molecule has an active site into which a substrate molecule fits in perfectly. At the end of each reaction the enzyme is broken down into 2 products, in this case starch is broken down by amylase into maltose. This mechanism is called the lock and key hypothesis.

The pH is one of the factors that affect the rate of a reaction. There are other factors like temperature, substrate concentration and enzyme concentration. I will summarise their importance shortly.

If there is an increase in temperature the reaction will also increase. The reaction rate will rise up to the temperature where it works best, which is called the optimum temperature. If then the temperature still continues rising the reaction will not increase but the enzyme will be denaturated. If there is an increase in the substrate concentration or in the enzyme concentration the reaction will also increase. But again only up to a certain point. Until the point where all active sites are filled with substrate molecules, and the reaction is at a constant level.

Join now!

The pH; even a fairly noticeable change in the pH can change the reaction heavily. The optimum pH is found where the reaction works best. When the pH is then still rising the enzyme will not be broken down, (most of the times), the reaction will start decreasing again.(refer to graph #1)

For starch the optimum pH is supposed to be around 7 which is neutral.

Therefore I predict that the reaction will work best at a pH of  7. It will be lowest at around 1,  at two I expect it to slightly increase, so with 4. because of ...

This is a preview of the whole essay