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 molecules has the minimum lifespan, we will analyze the lifespan of each type of RNA and DNA mentioned in the question: mRNA, rRNA, tRNA, and DNA.

### Step-by-Step Solution:

1. **Identify the Types of RNA and DNA**:
- The question lists four types of nucleic acids: mRNA (messenger RNA), rRNA (ribosomal RNA), tRNA (transfer RNA), and DNA (deoxyribonucleic acid).

2. **Understand the Function of Each Molecule**:
- **mRNA**: This molecule carries genetic information from DNA to the ribosomes, where proteins are synthesized.
- **rRNA**: This is a structural and functional component of ribosomes, playing a crucial role in protein synthesis.
- **tRNA**: This molecule helps in the translation process by bringing the appropriate amino acids to the ribosome during protein synthesis.
- **DNA**: This is the genetic material that stores all the hereditary information and has a long lifespan, as it remains in the cell for the lifetime of the organism.

3. **Compare Lifespans**:
- **mRNA**: Has a very short lifespan, typically ranging from 1 to 3 minutes in the cell before it is degraded.
- **rRNA**: Generally has a longer lifespan as it is stable and forms part of the ribosome structure.
- **tRNA**: Also has a relatively longer lifespan compared to mRNA, as it is recycled multiple times during protein synthesis.
- **DNA**: Has the longest lifespan, as it can persist for the entire life of the cell and is replicated during cell division.

4. **Conclusion**:
- Based on the analysis, mRNA has the minimum lifespan among the options provided. It is quickly synthesized and degraded after its function of transferring genetic information to ribosomes is fulfilled.

### Final Answer:
The molecule with the minimum lifespan is **mRNA**.

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