Protein digestion occurs in the stomach and duodenum in which 3 main enzymes, pepsin secreted by the stomach and trypsin and chymotrypsin secreted by the pancreas, break down food proteins into polypeptides that are then broken down by various exopeptidases and dipeptidases into amino acids. The digestive enzymes however are mostly secreted as their inactive precursors, the zymogens. For example, trypsin is secreted by pancreas in the form of trypsinogen, which is activated in the duodenum by enterokinase to form trypsin. Trypsin then cleaves proteins to smaller polypeptides. COUNT 5
QSN1 Where does protein digestion occur? ANS1 in the stomach and duodenum QSN2 What are the three main enzymes that break down food? ANS2 pepsin secreted by the stomach and trypsin and chymotrypsin QSN3 What are digestive enzymes mostly secreted as? ANS3 inactive precursors, the zymogens QSN4 What are dipeptidases broken down into? ANS4 amino acids QSN5 What organ secretes chymotrypsin? ANS5 the pancreas