Give one example of a prosthetic group.

Explanation

**Step-by-Step Solution:**

1. **Define Prosthetic Group**: A prosthetic group is a type of cofactor that is tightly bound to an enzyme or protein. This means that it is not easily removed and plays a crucial role in the enzyme's activity.

2. **Identify Characteristics**: Prosthetic groups can be either metal ions or small organic molecules. They are essential for the proper functioning of the enzyme.

3. **Examples of Prosthetic Groups**:
- **Metal Ions**: Common examples include iron (Fe), cobalt (Co), magnesium (Mg), and copper (Cu). These metal ions can be integral to the enzyme's active site and are necessary for catalysis.
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