Nirenberg synthesized an m-RNA containing 34 poly-Adenine (A-A-A-A-A-A-A----) and found a polyeptide formed of 11 poly-lysine this proved that genetic code for lysine was

Options

A. one-adenine
B. A-A doublet
C. A-A-A triplet
D. Many adenines

Answer

To solve the question regarding Nirenberg's experiment and the genetic code for lysine, we can break it down into the following steps:

### Step-by-Step Solution:

1. **Understanding the Experiment**: Nirenberg synthesized an mRNA strand consisting of 34 adenine nucleotides (A). This means the sequence of the mRNA is represented as AAAAA... (34 times).

2. **Polypeptide Formation**: When this mRNA was used in a translation process, it resulted in the formation of a polypeptide chain composed of 11 lysine amino acids.

3. **Determining the Codon**: Each amino acid is encoded by a specific triplet of nucleotides (codon) in the mRNA. Since 11 lysines were formed from the 34 adenines, we need to determine how many adenines are required to code for one lysine.

4. **Calculating the Codon Requirement**:
- Total adenines = 34
- Total lysines = 11
- To find out how many adenines are needed for one lysine, we can divide the total number of adenines by the total number of lysines:
\[ \text{Adenines per lysine} = \frac{34 \text{ adenines}}{11 \text{ lysines}} \approx 3.09 \]
- This result indicates that, on average, approximately 3 adenines are required to code for one lysine.

5. **Conclusion**: Since the genetic code is based on triplets, we can conclude that one triplet codon (which consists of 3 nucleotides) codes for one amino acid. Therefore, the genetic code for lysine is a triplet codon.

6. **Final Answer**: The genetic code for lysine is a triplet (3 nucleotides).