First code of every mRNA is

Options

A. either AUG or GUG
B. elther AUG OR UAG
C. either GUG or UAA
D. elther UGA or UAA

Answer

To answer the question "What is the first code of every mRNA?", we can follow these steps:

### Step-by-Step Solution:

1. **Understanding mRNA and Codons**:
- mRNA (messenger RNA) is a type of RNA that conveys genetic information from DNA to the ribosome, where proteins are synthesized.
- Codons are sequences of three nucleotides in mRNA that correspond to specific amino acids or signals during protein synthesis.

2. **Identifying the Start Codon**:
- The first codon of an mRNA molecule is known as the start codon. This codon signals the beginning of translation, the process by which proteins are synthesized from mRNA.

3. **Recognizing the Start Codon**:
- The universally recognized start codon is **AUG**. This codon not only initiates the translation process but also codes for the amino acid **methionine**.

4. **Considering Other Options**:
- While AUG is the primary start codon, there are other codons like GUG that can also serve as start codons in certain organisms or conditions. However, AUG is the most common and widely accepted start codon.

5. **Evaluating the Given Options**:
- The options provided are:
- A) Either AUG or GUG
- B) Either AUG or UAG
- C) Either GUG or UAA
- D) Either UGA or UAA
- Among these, the first option (AUG or GUG) correctly identifies the start codon.

6. **Conclusion**:
- Therefore, the correct answer to the question "What is the first code of every mRNA?" is **A) Either AUG or GUG**.