Digestion of Starch & Protein: Breaking Down Food for Energy

Starch and protein are two key nutrients in your diet, but they’re too large to be absorbed directly by your body. Chemical digestion breaks them into smaller molecules, making them easier to absorb and use.

 

Digestion of Starch

How Starch is Broken Down

Mouth:

• Enzyme: Amylase (from saliva).
• Action: Amylase breaks starch into maltose (a smaller sugar). $$\text{Starch} \xrightarrow{Amylase} \text{Maltose}$$

Small Intestine:

• Enzyme: Maltase, located in the epithelium lining of the small intestine(on the walls of the small intestine).
• Action: Maltase breaks maltose into glucose. $$\text{Maltose} \xrightarrow{Maltase} \text{Glucose}$$

 

Digestion of Protein

How Protein is Broken Down

Stomach:

• Enzyme: Pepsin (a protease in gastric juice).
• Conditions: Works in an acidic environment (created by hydrochloric acid).
• Action: Pepsin breaks proteins into smaller chains called peptides. $$\text{Protein} \xrightarrow{Pepsin} \text{Peptides}$$

Small Intestine:

• Enzyme: Trypsin (produced by the pancreas).
• Conditions: Works in an alkaline environment (neutralized by bile).
• Action: Trypsin breaks peptides into individual amino acids. $$\text{Peptides} \xrightarrow{Trypsin} \text{Amino Acids}$$

 

Why are Amino Acids Important?

• Amino acids are absorbed into the blood and used to build proteins in the body, like enzymes and muscle tissue.