Which component is NOT part of an operon?

In the context of molecular biology, an operon is a functional unit of genomic DNA that contains a cluster of genes under the control of a single promoter and regulatory elements such as an operator. The important components of an operon include the gene sequence, which encodes the proteins, and the operator, which is a segment of DNA that a repressor protein can bind to, thereby regulating the transcription of the genes in the operon.

Codons, on the other hand, are sequences of three nucleotides found within the messenger RNA (mRNA) that correspond to specific amino acids during protein synthesis. While codons play a crucial role in translating the genetic code into proteins, they are not considered a structural part of the operon itself. Instead, codons are part of the mRNA produced from the operon’s gene sequences.

The distinction between an operon's components and the role of codons within protein synthesis highlights why codons do not fall under the category of operon components. Hence, the correct answer is that codons are not part of an operon.