Codon

Definition

A codon is a sequence of three nucleotides that together form a unit of genetic code in a DNA or RNA molecule. Each codon corresponds to a specific amino acid or stop signal during protein synthesis.

5 Must Know Facts For Your Next Test

1. There are 64 possible codons in the genetic code, including one start codon and three stop codons.
2. The start codon AUG also codes for the amino acid methionine.
3. Stop codons (UAA, UAG, UGA) signal the end of translation and do not code for any amino acids.
4. Codons are read in the 5' to 3' direction on mRNA during translation.
5. Each amino acid can be specified by more than one codon due to the redundancy of the genetic code.

Review Questions

• How many nucleotides make up a single codon?
• Which codon serves as both a start signal and codes for methionine?
• What is the primary function of stop codons?

Related terms

Translation: The process by which ribosomes synthesize proteins using mRNA as a template.

mRNA: Messenger RNA; it carries genetic information from DNA to the ribosome where proteins are synthesized.

Amino Acid: Organic compounds that combine to form proteins and are coded by specific sequences of three nucleotides (codons).