Which was the first catalytic molecule during evolution of life?

Options

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

Answer

To answer the question "Which was the first catalytic molecule during the evolution of life?", we will evaluate the options provided: DNA, rRNA, tRNA, and mRNA.

### Step-by-Step Solution:

1. **Understanding the Role of DNA**:
- DNA (deoxyribonucleic acid) is primarily known for its role as the genetic material in organisms. It stores and transmits genetic information but does not have catalytic properties. Therefore, DNA cannot be considered the first catalytic molecule.
- **Hint**: Remember that catalytic molecules are involved in facilitating chemical reactions, not just storing information.

2. **Evaluating rRNA**:
- rRNA (ribosomal RNA) is a crucial component of ribosomes, which are the sites of protein synthesis in cells. rRNA plays a catalytic role in the formation of peptide bonds during protein synthesis. This suggests that rRNA has catalytic properties, making it a strong candidate for the first catalytic molecule.
- **Hint**: Think about the role of rRNA in protein synthesis and how it contributes to the formation of proteins.

3. **Considering tRNA**:
- tRNA (transfer RNA) is responsible for transporting amino acids to the ribosome during protein synthesis. While it is essential for the process, it does not have catalytic activity itself. Therefore, tRNA cannot be the first catalytic molecule.
- **Hint**: Focus on the function of tRNA and its role in the translation process.

4. **Analyzing mRNA**:
- mRNA (messenger RNA) carries genetic information from DNA to the ribosome for protein synthesis. It serves as a template for translation but does not catalyze any reactions. Thus, mRNA is not the first catalytic molecule.
- **Hint**: Consider the function of mRNA in the flow of genetic information and its lack of catalytic activity.

5. **Conclusion**:
- Based on the analysis of all four options, rRNA is the only molecule that exhibits catalytic properties, specifically in the context of protein synthesis. Therefore, the correct answer to the question is **rRNA**.

### Final Answer:
The first catalytic molecule during the evolution of life is **rRNA**.