Dinucleotide is obtained by joining two nucleotides together by phosphodiester linkage. Between which carbon atoms of pentose sugars of nucleotides are these linkages present ?
(a) 5' and 3'
(b) 1' and 5'
(c) 5' and 5'
(d) 3' and 3'

Options

A. 5' and 3'
B. 1' and 5'
C. 5' and 5'
D. 3' and 3'

Explanation

To answer the question regarding the formation of a dinucleotide through phosphodiester linkage, we need to understand the structure of nucleotides and how they connect to form a dinucleotide.

### Step-by-Step Solution:

1. **Understanding Nucleotide Structure**:
- A nucleotide consists of three main components: a nitrogenous base, a pentose sugar (which can be ribose or deoxyribose), and a phosphate group.
- The pentose sugar has five carbon atoms, labeled as 1', 2', 3', 4', and 5'.

2. **Identifying the Phosphate Group Attachment**:
- The phosphate group is attached to the 5' carbon of the pentose sugar. This is crucial for the formation of the dinucleotide.

3. **Linking Two Nucleotides**:
- When two nucleotides join to form a dinucleotide, the phosphate group of one nucleotide connects to the 3' carbon of the other nucleotide's sugar.
- This connection is known as a phosphodiester linkage.

4. **Conclusion**:
- Therefore, the phosphodiester linkage in a dinucleotide is formed between the 5' carbon of one nucleotide and the 3' carbon of the adjacent nucleotide.
- The correct answer to the question is (a) 5' and 3'.

### Final Answer:
The phosphodiester linkage in a dinucleotide is present between the 5' and 3' carbon atoms of the pentose sugars of the nucleotides.

---