In a DNA molecule, the phosphate group is attached to _______ cabon of the sugar residue of its own nucleotide and _____ carbon of the sugar residue of the next nucleotide by _________ bonds.

Options

A. 5', 3', phosphodiester
B. 5',3', glycosidic
C. 3',5', phosphodiester
D. 3', 5', glycosidic

Explanation

To answer the question, we need to understand the structure of a DNA molecule, particularly how the phosphate groups are connected to the sugar residues in the nucleotides.

### Step-by-Step Solution:

1. **Identify the Components of a Nucleotide**:
A nucleotide consists of three main components: a phosphate group, a sugar (deoxyribose in DNA), and a nitrogenous base.

2. **Understanding the Sugar Structure**:
The sugar in DNA is a pentose sugar, which means it has five carbon atoms. These are numbered as follows:
- Carbon 1 (C1) is attached to the nitrogenous base.
- Carbon 2 (C2) has a hydroxyl group (OH) in RNA but is just hydrogen (H) in DNA.
- Carbon 3 (C3) has a hydroxyl group (OH).
- Carbon 4 (C4) is part of the sugar ring.
- Carbon 5 (C5) is attached to the phosphate group.

3. **Phosphate Group Attachment**:
The phosphate group of one nucleotide is attached to the 5th carbon (C5) of its own sugar residue.

4. **Connection to the Next Nucleotide**:
The phosphate group also forms a bond with the 3rd carbon (C3) of the sugar residue of the next nucleotide.

5. **Type of Bond Formed**:
The bond that connects the phosphate group of one nucleotide to the sugar of the next nucleotide is called a phosphodiester bond. This bond is formed through a dehydration reaction, linking the phosphate group of one nucleotide to the hydroxyl group of the sugar of the next nucleotide.

### Final Answer:
In a DNA molecule, the phosphate group is attached to **5th carbon** of the sugar residue of its own nucleotide and **3rd carbon** of the sugar residue of the next nucleotide by **phosphodiester** bonds.

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