What is true about ribosomes ?

Options

A. These are composed of ribonucleic acid and proteins
B. These are found only in eukaryotic cells
C. These are self-splicing introns of some RNAs
D. The prokaryotic ribosomes are 80 S, where "S" stands for sedimentation coefficient.

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. **Analyzing the Statements**:
- **Statement 1**: "They are composed of ribonucleic acid and protein."
- This statement is **true**. Ribosomes are indeed made up of ribonucleic acid (RNA) and proteins.

- **Statement 2**: "They are found in only eukaryotic cells."
- This statement is **false**. Ribosomes are present in both prokaryotic and eukaryotic cells.

- **Statement 3**: "These are self-slicing in terms of some RNAs."
- This statement is **false**. Self-splicing is a characteristic of certain introns that can act as ribozymes, but it does not apply to ribosomes as a whole.

- **Statement 4**: "The prokaryotic ribosomes are 80S."
- This statement is **false**. Prokaryotic ribosomes are actually 70S, while eukaryotic ribosomes are 80S.

3. **Conclusion**: After analyzing all statements, the only true statement about ribosomes is that they are composed of ribonucleic acid and proteins.

### Final Answer:
The true statement about ribosomes is that they are composed of ribonucleic acid and proteins.

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