Enzymes are biological catalysts; catalysts are substances that increase the rate of chemical reactions without being used up (BBC, 2010), without these catalysts it would take an extremely long time for these reactions to take place. The enzyme used in this particular experiment was pepsin; pepsin is a zymogen of pepsinogen. Pepsinogen is activated by hydrochloric acid, which is released from parietal cells in the stomach lining. The hormone gastrin and the vagus nerve trigger the release of both pepsinogen and hydrochloric acid from the stomach lining when food is ingested. Hydrochloric acid creates an acidic environment, which allows pepsinogen to unfold and cleave itself in an autocatalytic fashion, generating pepsin. (Life Science Network, 2010)
A lot can be learnt about enzymes by studying the rate of enzyme catalyzed reactions, these rates of reaction can be studied in various ways. In this experiment, using a range of different temperatures, the enzyme pepsin will be mixed with egg albumen. This is high in protein and bound to the dye Coomassie blue to gain a light absorbance reading using a spectrophotometer and in effect see how much protein has been digested by the pepsin.
The geologic time scale is the calendar for events in Earth history. It subdivides all time into named units of abstract time called escending order of duration eons, eras, periods, epochs, and ages.
