The eukaryotic ribosomes are 80 S, while the prokaryotic ribosomes are 70 S. Here'S' stands for .............. it indirectly a measure of ................... :-

Options

A. Svedberg unit , number of r-RNA in ribosome
B. Smooth surface, surface area of ribosome
C. Shortest organelle, size
D. Sedimentation coefficient, size and density

Answer

To solve the question regarding eukaryotic and prokaryotic ribosomes, we will analyze the information step by step.

### Step-by-Step Solution:

1. **Understanding Ribosome Composition**:
- Eukaryotic ribosomes are referred to as 80S, while prokaryotic ribosomes are referred to as 70S. The 'S' in these terms is significant.

2. **Identifying What 'S' Stands For**:
- The 'S' stands for the Svedberg unit, which is a measure of sedimentation rate during centrifugation. It is not a direct measure of mass but rather indicates how quickly the ribosome sediments in a centrifugal field.

3. **Understanding Sedimentation Rate**:
- The sedimentation rate is influenced by the size, shape, and density of the ribosome. Therefore, while 'S' indicates the Svedberg unit, it indirectly measures the size and density of the ribosomal components.

4. **Conclusion**:
- Therefore, the correct answer to the question is:
- 'S' stands for **Svedberg unit** and it indirectly measures **size and density**.

### Final Answer:
- The eukaryotic ribosomes are 80 S, while the prokaryotic ribosomes are 70 S. Here 'S' stands for **Svedberg unit**; it indirectly measures **size and density**.

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