Read the following statements and find out incorrect statements :

Options

A. DNA exist a double helix structure
B. Two strands of polynucleotides in DNA are antiparallel
C. Bond between the phosphate and hydroxyl group of sugar is glycosidic bond
D. In DNA, pitch would be 34Å

Answer

To solve the question of identifying the incorrect statement from the provided options, we will analyze each statement one by one.

### Step-by-Step Solution:

1. **Statement 1: DNA exists as a double helical structure.**
- This statement is **correct**. DNA is known to have a double helical structure, which consists of two strands that wind around each other.

2. **Statement 2: The two strands of polynucleotide in DNA are antiparallel.**
- This statement is also **correct**. The two strands of DNA run in opposite directions; one strand runs from the 5' to 3' direction, while the other runs from the 3' to 5' direction, which is referred to as antiparallel.

3. **Statement 3: The bond between phosphate and hydroxyl group of the sugar is a glycosidic bond.**
- This statement is **incorrect**. The bond that forms between the phosphate group and the hydroxyl group of the sugar is known as a **phosphodiester bond**, not a glycosidic bond. Glycosidic bonds are formed between sugars and nitrogenous bases.

4. **Statement 4: The distance between one base pair in DNA is 0.34 nanometers (or 3.4 angstroms).**
- This statement is **correct**. The distance between each base pair in the DNA structure is indeed approximately 0.34 nanometers (or 3.4 angstroms), and after every 10 base pairs, the DNA helix makes a complete turn.

### Conclusion:
The incorrect statement among the options is **Statement 3**: "The bond between phosphate and hydroxyl group of the sugar is a glycosidic bond."

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