Question

Both $\text{DNA}$ and $\text{RNA}$ are chiral molecules. The chirality in $\text{DNA}$ and $\text{RNA}$ arises due to the presence of :

• A. $\text{D}$-sugar component
• B. Phosphodiester linkage
• C. $\text{L}$-sugar component
• D. Nitrogenous bases

Hint:

The chirality of natural biopolymers (proteins, nucleic acids) stems from the chiral centers present in their primary building blocks (L-amino acids, D-sugars).

Answer 1

The Correct Option is A

Step 1: DNA and RNA are polymers made up of nucleotide units. Step 2: Each nucleotide consists of: \begin{itemize} \item A nitrogenous base \item A phosphate group \item A pentose sugar \end{itemize} Step 3: The sugars present are: \[ \text{DNA: 2-deoxy-D-ribose}, \quad \text{RNA: D-ribose} \] Step 4: These sugars contain multiple asymmetric (chiral) carbon atoms. Step 5: The phosphate group and nitrogenous bases are achiral, whereas the sugar unit is chiral. Step 6: Hence, the overall chirality of DNA and RNA originates from the D-sugar component. Therefore, correct answer is (1) D-sugar component.