Which one of the following statement is not correct

Options

A. Cysteine is coded by UGU and UGC codons
B. Tyrosine is coded by UAU and UAC codons
C. UAA codon codes for lysine
D. UGG codon codes for tryptophan

Explanation

To determine which statement is not correct regarding the genetic code, we will analyze each statement provided.

### 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 mRNA is translated into the sequence of amino acids in proteins. This code is read in groups of three nucleotides called codons.

2. **Analyzing the Statements**:
- **Statement 1**: "UGU and UGC codon code for 16 amino acids."
- **Evaluation**: This statement is correct. UGU and UGC both code for the amino acid Serine.

- **Statement 2**: "Tyrosine is coded by UAU and UAC."
- **Evaluation**: This statement is correct. UAU and UAC both code for the amino acid Tyrosine.

- **Statement 3**: "UAA codon codes for lysine."
- **Evaluation**: This statement is incorrect. UAA is a stop codon and does not code for any amino acid. Lysine is coded by AAA and AAG.

- **Statement 4**: "UGG codon codes for Tryptophan."
- **Evaluation**: This statement is correct. UGG codes for the amino acid Tryptophan.

3. **Conclusion**: The statement that is not correct is **Statement 3**: "UAA codon codes for lysine."

### Final Answer:
The statement that is not correct is: **"UAA codon codes for lysine."**

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