The first codon discovered by Nirenberg and Matthei was `:`

Options

A. CCC
B. GGG
C. UUU
D. AAA

Answer

**Step-by-Step Solution:**

1. **Understanding Codons**: Codons are sequences of three nucleotides in mRNA that correspond to specific amino acids or stop signals during protein synthesis.

2. **Historical Context**: The question refers to the discovery of codons, which was a significant milestone in genetics. Scientists Nirenberg and Matthaei played a crucial role in deciphering the genetic code.

3. **Homopolymers and Heteropolymers**: Nirenberg and Matthaei used homopolymers (RNA sequences made up of the same nucleotide repeated) to identify specific codons. They synthesized RNA molecules with defined sequences.

4. **The First Codon**: The first codon that was discovered by Nirenberg and Matthaei was the homopolymer "UUU". They found that this codon coded for the amino acid phenylalanine.

5. **Conclusion**: Therefore, the answer to the question is that the first codon discovered by Nirenberg and Matthaei was "UUU".

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