Which is seen in RNA but not seen in DNA?
**Core Concept**
The question is testing the student's knowledge of the fundamental differences between RNA and DNA. RNA (Ribonucleic acid) and DNA (Deoxyribonucleic acid) are both nucleic acids, but they have distinct structural and functional features. One key distinction is the presence of a specific functional group in RNA that is absent in DNA.
**Why the Correct Answer is Right**
RNA contains a hydroxyl (-OH) group at the 2' carbon of its sugar molecule, which is not present in DNA. This hydroxyl group is essential for the catalytic activity of certain RNA molecules, such as ribozymes, and is also involved in the formation of phosphodiester bonds between nucleotides. The absence of this group in DNA is due to the presence of a hydrogen atom at the 2' carbon, which is a result of the deoxyribose sugar molecule found in DNA.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is not provided, so we can't evaluate its correctness.
**Option B:** This option is not provided, so we can't evaluate its correctness.
**Option C:** This option is not provided, so we can't evaluate its correctness.
**Option D:** This option is not provided, so we can't evaluate its correctness.
**Clinical Pearl / High-Yield Fact**
The presence of the hydroxyl group in RNA is crucial for its catalytic activity and is a key factor in its ability to perform functions such as protein synthesis and RNA splicing.
**Correct Answer:** A. Hydroxyl (-OH) group.