In a DNA strand the nucleotides are linked together by

Options

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

Answer

To answer the question "In a DNA strand the nucleotides are linked together by," we need to analyze the structure of DNA and the types of bonds that connect its components.

### Step-by-Step Solution:

1. **Understanding Nucleotide Structure**:
- A nucleotide is the basic building block of DNA. Each nucleotide consists of three components: a phosphate group, a five-carbon sugar (deoxyribose in DNA), and a nitrogenous base (adenine, thymine, cytosine, or guanine).

2. **Identifying the Bonds in DNA**:
- In DNA, nucleotides are linked together to form a long chain. The linkage occurs between the phosphate group of one nucleotide and the sugar of the next nucleotide.

3. **Types of Bonds**:
- **Glycosidic Bond**: This bond connects the nitrogenous base to the sugar in a nucleotide. It does not link nucleotides together in a strand.
- **Phosphodiester Bond**: This is the bond that connects the phosphate group of one nucleotide to the sugar of the next nucleotide. This bond forms the backbone of the DNA strand.
- **Peptide Bond**: This bond links amino acids together in proteins, not nucleotides in DNA.
- **Hydrogen Bond**: These bonds occur between the nitrogenous bases of two complementary DNA strands, holding the two strands together, but they do not link nucleotides within a single strand.

4. **Conclusion**:
- The correct answer is that in a DNA strand, the nucleotides are linked together by **phosphodiester bonds**.

### Final Answer:
In a DNA strand, the nucleotides are linked together by **phosphodiester bonds**.

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