Operons are present in which group and rare in which?

Operons are present in which group and rare in which?

• A. Prokaryotes; Eukaryotes
• B. Eukaryotes; Prokaryotes
• C. Both; Neither
• D. None; All

Answer: (A)

Operons are a way to coordinate the expression of multiple genes that function together, bundled under a single promoter and regulatory region. This setup is characteristic of many prokaryotes, where a single mRNA can carry several genes (polycistronic mRNA) and the cell can turn on or off an entire pathway at once, as seen with the lac and trp operons in bacteria like E. coli. In eukaryotes, genes are usually regulated individually; each gene typically has its own promoter and produces its own monocistronic mRNA, so coordinated expression happens through other regulatory networks rather than an operon. There are rare exceptions in some eukaryotes, but operons, in the classic sense, are much more common in prokaryotes and uncommon in eukaryotes.

Operons are a way to coordinate the expression of multiple genes that function together, bundled under a single promoter and regulatory region. This setup is characteristic of many prokaryotes, where a single mRNA can carry several genes (polycistronic mRNA) and the cell can turn on or off an entire pathway at once, as seen with the lac and trp operons in bacteria like E. coli. In eukaryotes, genes are usually regulated individually; each gene typically has its own promoter and produces its own monocistronic mRNA, so coordinated expression happens through other regulatory networks rather than an operon. There are rare exceptions in some eukaryotes, but operons, in the classic sense, are much more common in prokaryotes and uncommon in eukaryotes.