Translating DNA to amino acids#

DNA is basically a physical code that is present in every living organism’s cell. Think of it as a serial number . To encode DNA into amino acids it should be broken down into codons

Codons are groups of three DNA bases, each of which corresponds to either an amino acid or a STOP, which terminates transcription.

A visual example would look something like this; the picture mentions the “start codon”, methionone, which is the typical start codon in most eukaryotic organisms. The picture also talks about mRNA translation, using uracil/U instead of thymine/T. It turns out that mRNA is one-to-one with DNA (RNA transcriptase produces RNA from DNA in the nucleus). We’ll be working with DNA in this class.


Now that we have codons, these codon could be checked against a translation table which basically holds the respective amino acid:

        'ATA':'I', 'ATC':'I', 'ATT':'I', 'ATG':'M',
        'ACA':'T', 'ACC':'T', 'ACG':'T', 'ACT':'T',
        'AAC':'N', 'AAT':'N', 'AAA':'K', 'AAG':'K',
        'AGC':'S', 'AGT':'S', 'AGA':'R', 'AGG':'R',
        'CTA':'L', 'CTC':'L', 'CTG':'L', 'CTT':'L',
        'CCA':'P', 'CCC':'P', 'CCG':'P', 'CCT':'P',
        'CAC':'H', 'CAT':'H', 'CAA':'Q', 'CAG':'Q',
        'CGA':'R', 'CGC':'R', 'CGG':'R', 'CGT':'R',
        'GTA':'V', 'GTC':'V', 'GTG':'V', 'GTT':'V',
        'GCA':'A', 'GCC':'A', 'GCG':'A', 'GCT':'A',
        'GAC':'D', 'GAT':'D', 'GAA':'E', 'GAG':'E',
        'GGA':'G', 'GGC':'G', 'GGG':'G', 'GGT':'G',
        'TCA':'S', 'TCC':'S', 'TCG':'S', 'TCT':'S',
        'TTC':'F', 'TTT':'F', 'TTA':'L', 'TTG':'L',
        'TAC':'Y', 'TAT':'Y', 'TAA':'_', 'TAG':'_',
        'TGC':'C', 'TGT':'C', 'TGA':'_', 'TGG':'W',

To encode DNA into amino acids:

  • Break down the DNA string into codons (i.e., groups of three)

  • Look each codon up in the table

  • Return the list of corresponding amino acids