Of the following which one is classified on the basis of sedimentation co-efficient?

Options

A. Endoplasmic reticulum
B. Ribosomes
C. Nucleus
D. Golgi complex

Answer

To solve the question "Of the following which one is classified on the basis of sedimentation co-efficient?", we will analyze the options provided: endoplasmic reticulum, ribosomes, nucleus, and Golgi complex.

### Step-by-Step Solution:

1. **Understanding Sedimentation Coefficient**:
- The sedimentation coefficient (S) is a measure of how fast a particle sediments in a centrifugal field. It is influenced by the mass, shape, and density of the particle.
- It is commonly used to classify cellular components, particularly ribosomes, based on their size and density.

2. **Analyzing the Options**:
- **Endoplasmic Reticulum**: This is a network of membranes involved in protein and lipid synthesis but is not classified based on sedimentation coefficients.
- **Ribosomes**: These are the molecular machines that synthesize proteins. Ribosomes are classified based on their sedimentation coefficients. In prokaryotes, they consist of a 50S and a 30S subunit, while in eukaryotes, they consist of a 60S and a 40S subunit. The 'S' denotes the sedimentation coefficient.
- **Nucleus**: This is the membrane-bound organelle that contains the cell's genetic material. It is not classified based on sedimentation coefficients.
- **Golgi Complex**: This organelle is involved in modifying, sorting, and packaging proteins and lipids. It is also not classified by sedimentation coefficients.

3. **Conclusion**:
- Among the options provided, ribosomes are the only cellular structures that are classified based on sedimentation coefficients.

### Final Answer:
The correct answer is **ribosomes**.

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