Stop codon facts for kids

A stop codon is a special signal found in our body's instruction manual, the genetic code. It's like a "full stop" at the end of a sentence. This signal is a short message made of three tiny building blocks called nucleotides. It's found in something called messenger RNA (mRNA), and its main job is to tell the cell to stop making a protein.

Just as a full stop tells you a sentence is finished, a stop codon tells the cell that the instructions for a specific gene are complete. This important process of reading the instructions and building a protein is called genetic translation. Stop codons are also known as termination codons or chain termination codons. There are three main types of stop codons: UAA, UAG, and UGA.

How Proteins Are Made

Our bodies are constantly making proteins, which are essential for almost everything we do. Proteins are built from smaller units called amino acids, linked together in long chains called polypeptides.

Most of the messages (codons) in messenger RNA tell the cell which amino acid to add next to the growing polypeptide chain. But when the cell reaches a stop codon, it's a signal to halt. This means the process of adding amino acids stops, and the polypeptide chain is finished. This completed chain can then fold into a working protein.

Images for kids

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  An example of a single base deletion forming a stop codon.

See also

In Spanish: Codón de terminación para niños