RNA responsible for directing proper sequence of amino acids in protein synthesis is:

Options

A. Chromosomal RNA
B. Ribosomal RNA
C. Transfer RNA
D. Messenger RNA

Answer

To answer the question regarding which RNA is responsible for directing the proper sequence of amino acids in protein synthesis, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Protein Synthesis**:
- Protein synthesis occurs in two main stages: transcription and translation. In this context, we are focusing on translation, which is the process of synthesizing proteins from amino acids based on the genetic code.

2. **Role of mRNA**:
- Messenger RNA (mRNA) is synthesized during transcription and carries the genetic information from DNA to the ribosome, where protein synthesis occurs.

3. **Function of mRNA in Translation**:
- During translation, mRNA serves as a template for assembling amino acids in the correct order. The sequence of nucleotides in mRNA is read in sets of three, known as codons, each of which specifies a particular amino acid.

4. **Interaction with tRNA**:
- Transfer RNA (tRNA) is responsible for bringing the appropriate amino acids to the ribosome. Each tRNA molecule has an anticodon that pairs with a corresponding codon on the mRNA. While tRNA is essential for the process, it does not determine the sequence; it merely reads the codons.

5. **Conclusion**:
- Since mRNA provides the template that dictates the order of amino acids in a protein, it is the RNA responsible for directing the proper sequence of amino acids during protein synthesis.

### Final Answer:
The RNA responsible for directing the proper sequence of amino acids in protein synthesis is **mRNA (messenger RNA)**.