Here's how it works:

1. mRNA codons: The genetic code is carried by messenger RNA (mRNA), which is a sequence of codons (groups of three nucleotides). Each codon specifies a particular amino acid.

2. Stop codons: There are three stop codons: UAA, UAG, and UGA. These codons do not code for any amino acid. Instead, they signal the ribosome to stop translating the mRNA.

3. Release factor: When a ribosome encounters a stop codon, a protein called a release factor binds to the A site of the ribosome.

4. Chain termination: The release factor causes the polypeptide chain to detach from the tRNA in the P site, and the ribosome disassembles from the mRNA.

So, the stop codon acts like a "full stop" at the end of a sentence in the genetic code, signaling the end of protein synthesis.