How many different essential amino acids are there?

How many amino acids does this protein contain?

• Met/pge/val/his/lev/cys/gly/ser/his/lev/… stop There are 29 codons- so how many amino acids?

• Answer:

  If there are 29 codons, all but the last code for an amino acid (the last one is the stop codon, which doesn't have a corresponding amino acid), so there should be 28 amino acids. You didn't give the DNA sequence, so there's no way to tell if it's eukaryotic or prokaryotic (if it has introns -- DNA sequences that are not translated into a protein, but are present in the DNA -- it's eukaryotic). If the sequence only has 87 base pairs, it's prokaryotic. Working backwards, you'd get a number of possible DNA sequences, but only one would be the same as the original DNA sequence since some amino acids are encoded by several different codons (usually we say it's due to the "degenerative nature of codons").