Where does protein digestion start?

Where does protein digestion start?

• A. Mouth.
• B. Stomach.
• C. Small intestine.
• D. Esophagus.

Answer: (B)

Protein digestion begins in the stomach. The stomach’s acidic environment denatures proteins and activates pepsin from pepsinogen, allowing pepsin to cleave peptide bonds and produce shorter peptides. In the mouth, digestion is minimal for proteins (saliva targets mainly carbohydrates and mechanical chewing dominates), and the esophagus mainly transports material with no chemical digestion. The bulk of protein digestion and amino acid absorption occurs later in the small intestine with pancreatic proteases and brush-border enzymes, but the initial start happens in the stomach.

Protein digestion begins in the stomach. The stomach’s acidic environment denatures proteins and activates pepsin from pepsinogen, allowing pepsin to cleave peptide bonds and produce shorter peptides. In the mouth, digestion is minimal for proteins (saliva targets mainly carbohydrates and mechanical chewing dominates), and the esophagus mainly transports material with no chemical digestion. The bulk of protein digestion and amino acid absorption occurs later in the small intestine with pancreatic proteases and brush-border enzymes, but the initial start happens in the stomach.