Which one of the following has minimum life span?

Options

A. mRNA
B. rRNA
C. tRNA
D. DNA

Answer

To determine which of the following biomolecules has the minimum lifespan, we need to analyze the characteristics and functions of each option: mRNA, rRNA, tRNA, and DNA.

### Step-by-Step Solution:

1. **Understanding the Types of RNA**:
- **mRNA (Messenger RNA)**: This type of RNA is synthesized from DNA during transcription. It carries the genetic information from the nucleus to the cytoplasm, where it serves as a template for protein synthesis during translation.
- **rRNA (Ribosomal RNA)**: This RNA is a structural component of ribosomes, which are the sites of protein synthesis. rRNA molecules are relatively stable and have a longer lifespan as they are part of the ribosomal structure.
- **tRNA (Transfer RNA)**: This RNA helps in the translation process by bringing the appropriate amino acids to the ribosome. tRNA molecules are also relatively stable but have a shorter lifespan compared to rRNA.
- **DNA (Deoxyribonucleic Acid)**: DNA is the genetic material that is stable and has a very long lifespan, as it is the blueprint for all genetic information in an organism.

2. **Analyzing Lifespan**:
- mRNA is synthesized and used for protein synthesis, but it is not needed for long periods. Once the protein is synthesized, mRNA is rapidly degraded to prevent unnecessary accumulation and to regulate gene expression.
- rRNA and tRNA, while important, are more stable and persist longer in the cell.
- DNA is the most stable and has the longest lifespan, as it remains in the nucleus and is replicated during cell division.

3. **Conclusion**:
Based on the analysis, mRNA has the minimum lifespan among the options provided. It is a transient molecule that is quickly synthesized and then degraded after its role in protein synthesis is complete.

### Final Answer:
The biomolecule with the minimum lifespan is **mRNA (Messenger RNA)**.

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