What role does pepsin play in digestion?

Pepsin is an important enzyme involved in the digestive process, specifically targeting proteins. It is secreted in an inactive form known as pepsinogen and is activated in the acidic environment of the stomach. Once activated, pepsin catalyzes the hydrolysis of peptide bonds in proteins, breaking them down into smaller peptides. This process is essential because proteins are too large to be absorbed by the body, so they need to be reduced to smaller fragments. The action of pepsin is a key step in protein digestion, allowing subsequent enzymes in the small intestine to further break down peptides into amino acids, which can then be absorbed and utilized by the body for various functions.

The other options cover different types of nutrients. Carbohydrates are primarily broken down by enzymes like amylase, while lipids require emulsification by bile and digestion by lipases, which means they are not the role of pepsin. Therefore, the fundamental function of pepsin as a proteolytic enzyme is clearly to break down proteins.