Name four biologically important compounds of nitrogen.

Explanation

### Step-by-Step Solution:

1. **Identify the Question**: The question asks for four biologically important compounds that contain nitrogen.

2. **List the First Two Compounds**:
- The first two compounds are **DNA (Deoxyribonucleic Acid)** and **RNA (Ribonucleic Acid)**.
- Both of these are nucleic acids that play crucial roles in genetics and cellular functions.

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