Which of the following nucleic acids is present in an organism having 70S ribosomes only ?

Options

A. Single stranded DNA with protein coat
B. Double stranded circular naked DNA
C. Double stranded DNA enclosed in nuclear membrane
D. Double stranded circular DNA with histone proteins

Answer

To solve the question regarding which nucleic acid is present in an organism with 70S ribosomes, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Ribosomes**:
- Ribosomes are cellular structures made of ribonucleic acid (RNA) and proteins. They are essential for protein synthesis. There are two main types of ribosomes based on their sedimentation rates: 70S and 80S.

2. **Identifying the Type of Organism**:
- The "S" in 70S and 80S refers to the sedimentation coefficient, which is influenced by the size and density of the ribosomes.
- 70S ribosomes are typically found in prokaryotic organisms (like bacteria), while 80S ribosomes are found in eukaryotic organisms (like plants and animals).

3. **Characteristics of Prokaryotic Genetic Material**:
- Prokaryotes have a simpler structure and lack a membrane-bound nucleus. Their genetic material is usually in the form of double-stranded circular DNA, which is not enclosed by a nuclear membrane.

4. **Analyzing the Options**:
- **Option 1**: Single-stranded DNA with a protein coat - Incorrect, as prokaryotes do not have single-stranded DNA in this context.
- **Option 2**: Double-stranded circular naked DNA - Correct, as it accurately describes the genetic material of prokaryotes.
- **Option 3**: Double-stranded DNA enclosed in a nuclear membrane - Incorrect, as this is characteristic of eukaryotes.
- **Option 4**: Double-stranded circular DNA with histone proteins - Incorrect, as histone proteins are associated with eukaryotic DNA packaging.

5. **Conclusion**:
- The correct answer is **Option 2: Double-stranded circular naked DNA**. This is the type of nucleic acid present in organisms with 70S ribosomes, which are prokaryotes.