Digestion of protein starts from -

Options

A. Mouth
B. Stomach
C. Small intestine
D. Duodenum

Answer

**Step-by-Step Solution:**

1. **Understanding Protein Digestion**: The digestion of proteins involves breaking down complex protein molecules into smaller peptides and amino acids, which can be absorbed by the body.

2. **Location of Protein Digestion**: The digestion of proteins begins in the stomach. This is a crucial point as it distinguishes protein digestion from other types of digestion that may begin in the mouth or small intestine.

3. **Cells Involved in the Stomach**: In the stomach, there are specific cells that play a role in protein digestion:
- **Mucous Neck Cells**: These cells secrete mucus that protects the stomach lining.
- **Peptic Cells**: These cells secrete an inactive enzyme called **pepsinogen**.

4. **Activation of Pepsinogen**: When food enters the stomach, it stimulates the secretion of hydrochloric acid (HCl). The acidic environment activates pepsinogen, converting it into its active form, **pepsin**.

5. **Action of Pepsin**: Pepsin is a proteolytic enzyme that begins the process of protein digestion by breaking down proteins into smaller peptides called **peptones** and **proteases**.

6. **Conclusion**: Therefore, the digestion of protein starts in the stomach, where pepsin acts on the proteins present in the food.

**Final Answer**: The digestion of protein starts from the stomach.

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