In a DNA strand, the nucleotides are linked together by

Options

A. glycosidic bonds
B. phosphodiester bonds
C. peptide bonds
D. hydrogen bonds

Explanation

To solve the question "In a DNA strand, the nucleotides are linked together by?", we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Structure of DNA**:
- DNA (Deoxyribonucleic Acid) is a polynucleotide, meaning it is composed of many repeating units called nucleotides.
- Each nucleotide consists of three components: a nitrogenous base, a sugar (deoxyribose), and a phosphate group.

2. **Identify the Bonds in Nucleotides**:
- Within a nucleotide, the nitrogenous base is linked to the sugar by a bond known as a glycosidic bond.
- The phosphate group of one nucleotide is linked to the sugar of the next nucleotide.

3. **Determine the Type of Bond Linking Nucleotides**:
- The bond that links the phosphate group of one nucleotide to the sugar of the next nucleotide is called a phosphodiester bond.
- This bond forms the backbone of the DNA strand, allowing the nucleotides to be connected in a long chain.

4. **Consider Other Types of Bonds**:
- While hydrogen bonds are important in stabilizing the double helix structure of DNA by connecting complementary nitrogenous bases (e.g., A with T and C with G), they do not link nucleotides together in the strand.
- Peptide bonds are not relevant here as they are found in proteins, linking amino acids together.

5. **Conclude the Answer**:
- Therefore, the correct answer to the question is that in a DNA strand, the nucleotides are linked together by **phosphodiester bonds**.

### Final Answer:
The nucleotides in a DNA strand are linked together by **phosphodiester bonds**.

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