Examine the graph below.
The diagram shows a graph with pH on the x-axis, and three bell curves labeled Pepsin, Amylase, and Trypsin. Pepsin has a pH range between 2 and 4. Amylase has a pH range of 6 and 8. Trypsin has a pH range of 7 and 9. Amylase and Trypsin curves overlap.
Image © GNU Free Documentation License, Version 1.2, 2011
Creative Commons by SA
All enzymes have optimal conditions, where they work best. Pepsin, amylase, and trypsin are three enzymes involved in digestion. Amylase is secreted in the mouth, where the pH is between 6 and 8; pepsin is produced in the stomach, where the pH is between 2 and 4; and trypsin is released into the small intestine, where the pH is between 7 and 9.
Part 1: Using what you know about enzymes, why does pepsin work best in the stomach and not in the mouth?
Part 2: Normally, food moves from the mouth to the stomach. However, in people who suffer from gastric reflux, the pepsin enzyme moves up into the mouth. Based on what you know about how enzymes function best in different conditions, explain why the enzyme, pepsin, would not work the way it normally does when it is present in the mouth.
