The reason for this confusion might stem from the fact that the genetic code is degenerate. This means that multiple codons (three-nucleotide sequences in DNA) can code for the same amino acid.
For example, the amino acid Leucine can be coded by six different codons: UUA, UUG, CUU, CUC, CUA, and CUG.
Here's how it works:
1. DNA to mRNA: DNA is transcribed into messenger RNA (mRNA), which carries the genetic code from the nucleus to the ribosome.
2. mRNA to protein: The mRNA is translated into a protein using the genetic code. Each three-nucleotide sequence in mRNA (called a codon) corresponds to a specific amino acid.
3. Degeneracy: While multiple codons can code for the same amino acid, each codon will only code for *one* specific amino acid.
Therefore, a single DNA sequence will always result in a unique amino acid sequence because each codon codes for a specific amino acid, even if that same amino acid can be coded by multiple codons.
