From what I understand, the term operon is loosely defined to be a collection of genes that are found to be in the same proximity in a genome.

Some definitions enforce that an operon is only regulated by a single promoter and all of the genes are transcribed together.

If the above definition is strict, that would imply a couple of things

  1. Genes are opposite strands cannot be in the same operon (since they cannot be transcribed together)
  2. Overlapping genes cannot be in the same operon for the same reason.

I realize that part of the issue with these definitions stems from an ongoing investigation behind this phenomenon. But are there strict standards surrounding the definition an operon? What is the minimal definition of an operon?

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1 Answer 1


From Henderson's Dictionary of Biology 14 ed. An operon is: a type of gene organization in bacteria, in which the genes coding for the enzymes of a metabolic pathway are clustered together in the DNA and transcribed together into a single mRNA. This mRNA is then translated to give the individual proteins. The expression of all the genes in an operon is controlled by a single promoter.

I'm not sure what an overlapping gene is, but according to this definition, yes genes on opposite directions of a promoter or different loci cannot be a part of an operon because they wouldn't be on the same mRNA.


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