Antiparallel strands in DNA is due to

Options

A. Disulphide linkage
B. Hydrogen bond
C. Phosphodiester bond
D. Glycosidic bond

Answer

To solve the question "Antiparallel strands in DNA is due to", we will analyze the options provided and understand the structure of DNA.

### Step-by-Step Solution:

1. **Understanding DNA Structure**:
- DNA is composed of two strands that form a double helix. Each strand is made up of nucleotides, which consist of a sugar, a phosphate group, and a nitrogenous base.

2. **Definition of Antiparallel**:
- The term "antiparallel" refers to the orientation of the two strands of DNA. One strand runs in a 5' to 3' direction, while the other runs in a 3' to 5' direction. This means that the strands are aligned in opposite directions.

3. **Analyzing the Options**:
- **a. Disulfide linkage**: This refers to a covalent bond that forms between the sulfur atoms of cysteine residues in proteins, not relevant to DNA structure.
- **b. Hydrogen bonds**: These bonds form between complementary nitrogenous bases (A-T and G-C) in the DNA strands, providing stability but not causing the antiparallel arrangement.
- **c. Phosphodiester bonds**: These are the covalent bonds that link the sugar and phosphate groups of adjacent nucleotides in a single strand of DNA. They are responsible for the backbone of the DNA strand.
- **d. Glycosidic bonds**: These bonds connect the sugar to the nitrogenous base in a nucleotide, but they do not contribute to the antiparallel nature of the strands.

4. **Conclusion**:
- The antiparallel nature of DNA strands is primarily due to the orientation of the phosphodiester bonds that link the nucleotides together. The strands are complementary and aligned in opposite directions because of the way these bonds are formed between the 3' and 5' carbons of the sugar molecules.

Thus, the correct answer is **option C: phosphodiester bonds**.