The backbone of DNA chain is formed by____

Answer

To answer the question "The backbone of DNA chain is formed by____", we can follow these steps:

### Step-by-Step Solution:

1. **Understanding DNA Structure**:
- DNA (deoxyribonucleic acid) is a molecule that carries genetic information. It has a unique structure known as a double helix.

2. **Identifying the Components of DNA**:
- The DNA molecule consists of two main components: nucleotides and the backbone.

3. **Nucleotide Composition**:
- Each nucleotide is made up of three parts: a phosphate group, a deoxyribose sugar, and a nitrogenous base (adenine, thymine, cytosine, or guanine).

4. **Backbone Formation**:
- The backbone of the DNA strand is formed by alternating sugar and phosphate groups. Specifically, the sugar in DNA is deoxyribose.

5. **Final Answer**:
- Therefore, the backbone of the DNA chain is formed by **sugar phosphate**.

### Summary:
The backbone of the DNA chain is formed by sugar phosphate.

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