Which statement correctly describes introns in prokaryotes and archaea?

Which statement correctly describes introns in prokaryotes and archaea?

• A. All prokaryotes have introns
• B. Introns are abundant in bacteria
• C. Archaea lack introns
• D. Most prokaryotes lack introns; archaea have them

Answer: (D)

Introns are noncoding segments within genes that are removed during RNA processing. In prokaryotes, genes are typically uninterrupted, so introns are very rare and most prokaryotes lack them. Archaea do have introns in a subset of genes, though not as commonly as in eukaryotes. So, saying that most prokaryotes lack introns while archaea have them captures the real pattern: sparsity in prokaryotes and presence in some archaeal genes. The other statements overstate intron occurrence in bacteria or deny introns in archaea, which doesn’t fit what’s observed.

Introns are noncoding segments within genes that are removed during RNA processing. In prokaryotes, genes are typically uninterrupted, so introns are very rare and most prokaryotes lack them. Archaea do have introns in a subset of genes, though not as commonly as in eukaryotes. So, saying that most prokaryotes lack introns while archaea have them captures the real pattern: sparsity in prokaryotes and presence in some archaeal genes. The other statements overstate intron occurrence in bacteria or deny introns in archaea, which doesn’t fit what’s observed.