Answer :
Final answer:
The statement is true; amino acids are enzymatically broken down by trypsin and chymotrypsin in the small intestine, with trypsinogen and chymotrypsinogen first being activated by enzymes in the intestinal mucosa before catalyzing protein digestion.
Explanation:
The statement that amino acids are enzymatically broken down by pancreatic trypsin and chymotrypsin in the lumen of the small intestine is true. Proteins are initially digested into smaller polypeptides by stomach enzymes. Then, these polypeptides are further digested in the small intestine by pancreatic enzymes that are first secreted as inactive forms (trypsinogen and chymotrypsinogen) to avoid autodigestion of the pancreas.
Once in the small intestine, trypsinogen is converted to trypsin by the enzyme enteropeptidase. Trypsin then activates chymotrypsinogen into chymotrypsin. Together, these active enzymes break down large proteins into smaller peptides through the process of proteolysis. These peptides are then further catabolized into their constituent amino acids, which are absorbed through the intestinal wall into the bloodstream. Thus, chymotrypsin and trypsin play a critical role in protein digestion, preparing amino acids for absorption and subsequent protein synthesis.