What is the size of prokaryotic ribosomes?

Answer

### Step-by-Step Solution:

1. **Understanding Ribosomes**: Ribosomes are cellular structures responsible for protein synthesis. They can be found in both prokaryotic and eukaryotic cells.

2. **Types of Ribosomes**: Ribosomes are classified based on their sedimentation rate, which is measured in Svedberg units (S). In prokaryotes, ribosomes are referred to as 70S ribosomes, while in eukaryotes, they are 80S ribosomes.

3. **Subunits of Prokaryotic Ribosomes**: The prokaryotic ribosome (70S) is made up of two subunits: the larger subunit (50S) and the smaller subunit (30S).

4. **Size of Prokaryotic Ribosomes**: The size of prokaryotic ribosomes is approximately 20 nanometers in diameter.

5. **Conclusion**: Therefore, the size of prokaryotic ribosomes is 20 nanometers.