What is common between rennin, trypsin and amylase?

Options

A. All are part of succus entericus
B. All works at a pH lower than 7
C. All are chemically proteins
D. All are proteolytic enzymes

Answer

To determine what is common between rennin, trypsin, and amylase, we will analyze each enzyme and their characteristics step by step.

### Step 1: Identify the Enzymes
- **Rennin**: This enzyme is primarily found in infants and is secreted by the stomach. It is involved in the digestion of milk proteins and is classified as a proteolytic enzyme.
- **Trypsin**: This enzyme is secreted by the pancreas in an inactive form known as trypsinogen. It is activated in the small intestine and is also a proteolytic enzyme that digests proteins.
- **Amylase**: This enzyme is secreted by both the pancreas and salivary glands. It is responsible for the digestion of carbohydrates, not proteins.

### Step 2: Analyze the Common Characteristics
- All three enzymes are **enzymes**, which are biological catalysts that speed up chemical reactions in the body.
- All three enzymes are **proteins**. Enzymes are fundamentally proteins that facilitate biochemical reactions.
- **Rennin** and **trypsin** are both classified as **proteolytic enzymes**, meaning they break down proteins. However, **amylase** does not fit this classification as it digests carbohydrates.

### Step 3: Evaluate the Options
Given the options:
1. All are part of succus entericus.
2. All work at a pH lower than 7.
3. All are chemically proteins.
4. All are proteolytic enzymes.

- **Option 1**: Incorrect. Not all are part of succus entericus.
- **Option 2**: Incorrect. Trypsin works at a pH higher than 7.
- **Option 3**: Correct. All three enzymes are chemically proteins.
- **Option 4**: Incorrect. Only rennin and trypsin are proteolytic enzymes.

### Conclusion
The common characteristic among rennin, trypsin, and amylase is that **all are chemically proteins**.

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