Viruses have

Options

A. DNA enclosed in a protein coat
B. Prokaryotic nucleus
C. Single chromosome
D. Both DNA and RNA

Answer

**Step-by-Step Solution:**

1. **Understanding Viruses:** Viruses are unique entities that exhibit characteristics of both living and non-living things. They are often referred to as the connecting link between the two.

2. **Genetic Material:** Viruses contain genetic material, which can either be DNA or RNA, but never both. This is a crucial characteristic that distinguishes them from living organisms.

3. **Structure of Viruses:** The genetic material in viruses is enclosed within a protective protein coat known as a capsid. The capsid is made up of smaller units called capsomeres.

4. **Acellular Nature:** Viruses do not possess a cellular structure, meaning they lack a cell membrane and are therefore classified as acellular entities.

5. **Analyzing Options:**
- **Option 1:** "DNA enclosed in a protein coat" - This is correct as viruses can have DNA as their genetic material enclosed in a protein coat.
- **Option 2:** "Prokaryotic nucleus" - This is incorrect because viruses do not have a nucleus.
- **Option 3:** "Single chromosome" - This is misleading as some viruses may have more than one piece of genetic material, such as HIV which has two RNA molecules.
- **Option 4:** "Both DNA and RNA" - This is incorrect since viruses can only have either DNA or RNA, but not both.

6. **Conclusion:** Based on the analysis of the options, the correct answer is that viruses have "DNA enclosed in a protein coat."

**Final Answer:** Viruses have DNA enclosed in a protein coat.

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