Which of the following is not a salient features of genetic code

Options

A. 3 codons function as stop codons
B. codon is read in mRNA in a contiguous fashion.
C. there are no punctuations.
D. The code is nearly universal except in mitochondrial codons, and in some insects

Answer

To determine which of the following is not a salient feature of the genetic code, we will analyze each option provided in the context of the characteristics of the genetic code.

### Step-by-Step Solution:

1. **Understanding the Genetic Code**: The genetic code is a set of rules that defines how the sequence of nucleotides in DNA or RNA is translated into the sequence of amino acids in proteins. It consists of codons, which are triplets of nucleotides.

2. **Analyzing the Options**:
- **Option 1: 3 Codons function as Stop Codons**: This statement is true. There are three stop codons (UAA, UAG, UGA) that signal the termination of protein synthesis.
- **Option 2: Codons are read in a contiguous fashion**: This is also true. Codons are read sequentially without any gaps or punctuation marks, meaning they are read continuously.
- **Option 3: The code is nearly universal**: This statement is true as well. The genetic code is nearly universal among organisms, with some exceptions found in mitochondrial codons and certain protists.
- **Option 4: Codons are truly universal**: This statement is incorrect. While the genetic code is largely universal, there are exceptions, particularly in mitochondria and some specific organisms. Therefore, this option does not accurately describe a salient feature of the genetic code.

3. **Conclusion**: The option that is not a salient feature of the genetic code is that "Codons are truly universal." This is incorrect because there are exceptions to the universality of the genetic code.

### Final Answer:
The option that is not a salient feature of the genetic code is: **Codons are truly universal.**

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