which nitrogenous base is found in RNA but not DNA
The correct answer and explanation is:
The correct answer is C) Uracil.
Explanation:
RNA (ribonucleic acid) and DNA (deoxyribonucleic acid) are both nucleic acids, but they have some distinct differences in their structures. One of the key differences lies in the nitrogenous bases they contain.
DNA contains four nitrogenous bases: adenine (A), thymine (T), cytosine (C), and guanine (G). In contrast, RNA contains adenine (A), uracil (U), cytosine (C), and guanine (G). The major distinction here is the presence of uracil in RNA instead of thymine, which is found in DNA.
- Uracil vs. Thymine: In DNA, thymine pairs with adenine through hydrogen bonds, whereas in RNA, uracil performs this same function. Uracil is structurally similar to thymine but lacks a methyl group at the 5′ carbon position of the ring. This slight difference is one reason why uracil is used in RNA instead of thymine.
- Function of Uracil: The presence of uracil instead of thymine in RNA is crucial for the role of RNA in protein synthesis. Uracil is more reactive than thymine, which suits the temporary, single-stranded nature of RNA. This allows RNA molecules to quickly be synthesized, used for their specific function, and then degraded once they have served their purpose in processes like transcription and translation.
- Stability and Mutation Prevention: DNA’s use of thymine instead of uracil contributes to its stability and helps prevent mutation. Uracil, being more prone to mutation, would not be as suitable in the long-term storage of genetic information. In contrast, the use of thymine helps in maintaining the integrity of the genetic code in DNA.
In summary, uracil is the nitrogenous base found in RNA but not in DNA, playing a crucial role in the molecular processes that drive cellular functions.