If a bacterial protein contains 150 amino acids, then there would be 150 codons in the specification to construct the said protein. A codon is definces as a sequence of 3 RNA or DNA nucleotides which would correspond to a specific amino acid such that if you have 150 amino acids then you would also have 50 codons. THe start of a codon is the first codon that can be found in the messenger RNA that is translated by the ribosome.