How many effective codons are there for the synthesis of twenty amino acids?

Options

A. 64
B. 32
C. 60
D. 61

Answer

To determine how many effective codons are there for the synthesis of twenty amino acids, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Codons**:
- Codons are sequences of three nucleotides in mRNA that correspond to specific amino acids. Each codon is made up of combinations of four different nucleotides: adenine (A), uracil (U), cytosine (C), and guanine (G).

2. **Calculating Possible Codons**:
- Since codons are made up of three nucleotides, we can calculate the total number of possible codons using the formula \( 4^n \), where \( n \) is the number of nucleotides in the codon.
- For three nucleotides:
\[ 4^3 = 64 \]
- This means there are 64 possible codons.

3. **Determining Effective Codons**:
- Out of these 64 codons, 61 codons are used to code for the 20 amino acids.
- The remaining 3 codons are known as stop codons, which signal the termination of protein synthesis and do not code for any amino acid.

4. **Conclusion**:
- Therefore, the number of effective codons that can be used for the synthesis of the 20 amino acids is 61.

### Final Answer:
The number of effective codons for the synthesis of twenty amino acids is **61**.

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