Question

Describe protein digestion in humans.

Answer 1

Digestion of Proteins in Humans:

1. Protein digestion occurs in the stomach and duodenum.
2. Three main enzymes bring about protein digestion: pepsin secreted by the stomach and trypsin and chymotrypsin secreted by the pancreas.
3. These enzymes break down food proteins into polypeptides that are then broken down by various exopeptidases and polypeptidases into amino acids.
4. Then finally amino acids are absorbed into the bloodstream through the small intestine.

Digestion of Proteins in the stomach:

1. $\mathrm{Pepsinogen}\stackrel{\mathrm{HCL}}{\to }\mathrm{Pepsin}$
2. $\mathrm{Proteins}\stackrel{\mathrm{Pepsin}}{\to }\mathrm{Peptones}$

Digestion of Proteins in the small intestine:

1. $\mathrm{Trypsinogen}\stackrel{\mathrm{Enterokinase}}{\to }\mathrm{Trypsin}$
2. $\mathrm{Chymotrypsinogen}\stackrel{\mathrm{Trypsin}}{\to }\mathrm{Chymotrypsin}$
3. $\mathrm{Prokarboxypeptidase}\stackrel{\mathrm{Trypsin}}{\to }\mathrm{Carboxypeptidase}$
4. $\mathrm{Peptones}\stackrel{\mathrm{Trypsin}}{\to }\mathrm{Peptides}$
5. $\mathrm{Peptones}\stackrel{\mathrm{Chymotrypsin}}{\to }\mathrm{Peptides}$
6. $\mathrm{Peptides}\stackrel{\mathrm{Carboxypeptidase}}{\to }\mathrm{Small}\mathrm{peptides}+\mathrm{Amino}\mathrm{acids}$