Find the correct statement regarding DNA.

Options

A. Form a double helical structure made up of two polypeptide chain.
B. It is an acidic substance present in nucleus was first identified by F. Meischer in 1869.
C. Phosphate group is linked to 5' H of the nucleoside byglycosidic linkage .
D. All four deoxyribonucleotides are always equally present in the strands .

Answer

To solve the question "Find the correct statement regarding DNA," we will analyze each of the provided statements one by one.

### Step-by-Step Solution:

1. **Statement 1**: "It forms a double helical structure made up of two polypeptide chains."
- **Analysis**: DNA does indeed form a double helical structure; however, it is made up of two polynucleotide chains, not polypeptide chains. Polypeptides are chains of amino acids that make up proteins, while polynucleotides are chains of nucleotides that make up nucleic acids like DNA.
- **Conclusion**: This statement is **incorrect**.

2. **Statement 2**: "It is an acidic substance present in the nucleus, first determined by Friedrich Miescher in 1869."
- **Analysis**: This statement is accurate. DNA is indeed an acidic substance found in the nucleus of cells, and it was first isolated by Friedrich Miescher in 1869, who referred to it as "nuclein."
- **Conclusion**: This statement is **correct**.

3. **Statement 3**: "Phosphate group is linked to 5 prime hydrogen of the nucleoside by glycosidic linkage."
- **Analysis**: This statement is incorrect. The phosphate group is linked to the 5' carbon of the sugar in a nucleotide by a phosphodiester bond, not a glycosidic linkage. Glycosidic linkages are found in carbohydrates, connecting sugars to other molecules.
- **Conclusion**: This statement is **incorrect**.

4. **Statement 4**: "All the four deoxyribonucleotides are always equally present in the strands."
- **Analysis**: This statement is also incorrect. In a DNA molecule, the four types of deoxyribonucleotides (adenine, thymine, cytosine, and guanine) do not have to be present in equal amounts. The ratio of these nucleotides can vary depending on the specific DNA molecule.
- **Conclusion**: This statement is **incorrect**.

### Final Answer:
The correct statement regarding DNA is **Statement 2**: "It is an acidic substance present in the nucleus, first determined by Friedrich Miescher in 1869."

---