Differentiate between ‘RER’ and ‘SER’.

Explanation

### Step-by-Step Solution:

1. **Definition**:
- **Rough Endoplasmic Reticulum (RER)**: A type of endoplasmic reticulum that is studded with ribosomes on its cytoplasmic surface, giving it a "rough" appearance.
- **Smooth Endoplasmic Reticulum (SER)**: A type of endoplasmic reticulum that lacks ribosomes, resulting in a smooth appearance.

2. **Presence of Ribosomes**:
- **RER**: Contains ribosomes attached to its membrane, which are essential for protein synthesis.
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