Question

The correct statement(s) among the following is(are)

• A. In natural nucleic acids, the nucleosides are linked through phosphodiester bonds
• B. Natural nucleic acids have sulfur-containing heterocyclic bases
• C. The isoelectric point of arginine is higher than that of isoleucine
• D. The molecular weight of guanine is higher than that of cytosine

Hint:

Phosphodiester bonds link nucleosides in nucleic acids, forming the backbone of DNA and RNA. The correct isoelectric point comparison and molecular weight order should always be checked.

Answer 1

The Correct Option is A

Step 1: Analyze each statement.
- Option (A): This is correct. In natural nucleic acids like DNA and RNA, nucleosides (which are sugar + base) are linked through phosphodiester bonds to form the backbone of the strand.
- Option (B): This is incorrect. Natural nucleic acids (DNA, RNA) contain nitrogenous bases like adenine, thymine (uracil in RNA), guanine, and cytosine, which do not contain sulfur.
- Option (C): This is incorrect. Arginine has an isoelectric point of around 10.76, while isoleucine has an isoelectric point of around 6.0. Therefore, arginine's isoelectric point is higher.
- Option (D): This is incorrect. Guanine (molecular weight 151) has a higher molecular weight than cytosine (molecular weight 111).
Final Answer: \[ \boxed{\text{The correct answer is (A).}} \]