A stop codon is a nucleotide triplet in messenger RNA that signals the end of a protein during the translation process. Read about how this works, the different types of stop codons, and how a mutation can sometimes occur.

A start codon is a nucleotide triplet in a genetic sequence that occurs at the start of a protein's synthesis. Read about how this works and how a mutation can sometimes occur.

Try this interactive module from the Brooklyn College to help understand the genetic code and how changes in the code effect the final protein product.