In nucleosides, both base and sugar are joined by

Options

A. Hydrogen bond
B. N-glycoside bond
C. -S-S-bond
D. (1) and (3)

Answer

### Step-by-Step Solution:

1. **Understanding Nucleosides**:
- Nucleosides are compounds that consist of a nitrogenous base and a sugar (usually ribose or deoxyribose).

2. **Identifying the Bonds**:
- The question asks about the type of bond that connects the nitrogenous base to the sugar in nucleosides.

3. **Types of Bonds**:
- The options provided include:
- Hydrogen bond
- Glycosidic bond
- Sulfur-sulfur bond
- A combination of the first and third options.

4. **Correct Bond Identification**:
- The bond that connects the sugar to the nitrogenous base in nucleosides is known as a **glycosidic bond**. This is a type of covalent bond that forms between the anomeric carbon of the sugar and the nitrogen atom of the base.

5. **Eliminating Incorrect Options**:
- Hydrogen bonds are not responsible for the connection between the base and sugar; they are typically involved in stabilizing the structure of nucleic acids (like DNA and RNA).
- Sulfur-sulfur bonds are also not relevant in this context.
- Therefore, the only correct answer is the glycosidic bond.

6. **Conclusion**:
- The correct answer is that in nucleosides, the base and sugar are joined by a **glycosidic bond**.

### Final Answer:
In nucleosides, both base and sugar are joined by a **glycosidic bond**.

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