Protein Digestion + Absorption

What are proteases?

enzymes that digest proteins

Where does protein digestion begin?

stomach

Which enzyme is made/active in the stomach?

Pepsin

Pepsin hydrolyzes peptide bonds between which amino acids?

Tyrosine and phenylalanine

What happens to pepsin in the duodenum?

It is inactivated by alkaline pancreatic juice (pH 8)

Which enzymes continue protein digestion in the small intestine?

Trypsin and chymotrypsin

Pancreatic enzymes break polypeptides into what smaller units?

Oligopeptides

Oligopeptides are taken apart one amino acid at a time by how many enzymes?

Three

Which enzyme removes amino acids from the carboxyl (–COOH) end of a peptide chain?

Carboxypeptidase

Carboxypeptidase is secreted by which source?

Pancreas

Which enzyme removes amino acids from the amino (–NH₂) end of a peptide chain?

Aminopeptidase

Aminopeptidase is classified as what type of enzyme?

Brush border enzyme

Which enzyme splits dipeptides in the middle and releases two free amino acids?

Dipeptidase

Dipeptidase is classified as what type of enzyme?

Brush border enzyme

What do brush border enzymes produce at the end of protein digestion?

Free amino acids

Free amino acids are absorbed into which cells first?

Intestinal epithelial cells

After entering intestinal epithelial cells, amino acids move into the bloodstream by what mechanism?

Facilitated Diffusion

Where does the final transport of amino acids into the blood occur?

Basal side of intestinal epithelial cells