To code the 50 aminoacids in a polypeptide chain, what will be the minimum number of nucleotides in its cistron?

Options

A. 50
B. 153
C. 306
D. 300

Answer

To determine the minimum number of nucleotides required to code for a polypeptide chain of 50 amino acids, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the coding mechanism**: Each amino acid in a protein is coded by a triplet of nucleotides, known as a codon. This means that for every amino acid, three nucleotides are needed.

2. **Calculate nucleotides for amino acids**: To find the total number of nucleotides required for 50 amino acids, we multiply the number of amino acids by the number of nucleotides per amino acid:
\[ \text{Total nucleotides for amino acids} = 50 \text{ amino acids} \times 3 \text{ nucleotides/amino acid} = 150 \text{ nucleotides} \]

3. **Include the stop codon**: In addition to the nucleotides coding for the amino acids, we need to account for a stop codon, which signals the end of protein synthesis. A stop codon is also composed of three nucleotides.

4. **Calculate the total nucleotides**: Therefore, we add the nucleotides for the stop codon to the total calculated for the amino acids:
\[ \text{Total nucleotides} = 150 \text{ nucleotides} + 3 \text{ nucleotides (stop codon)} = 153 \text{ nucleotides} \]

5. **Conclusion**: The minimum number of nucleotides required in the cistron to code for a polypeptide chain of 50 amino acids is 153 nucleotides.

### Final Answer:
The minimum number of nucleotides in its cistron is **153**.

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