Prokaryotic Gene Structure and Organization

The prokaryotic genomes consist of coding and non-coding regions.

The coding regions contain nucleotide sequences that dictate the amino acid sequence for functional proteins, beginning with a start codon and ending with a stop codon.

tRNA and rRNA genes encode sequences for transfer RNA and ribosomal RNA. They are organized like the protein-coding genes, except their coding regions remain untranslated.

In contrast, non-coding regions include promoters, regulatory sequences, and terminators.

Promoters are upstream of the coding region, guiding the RNA polymerase to bind and initiate transcription.

Bacterial promoters contain the conserved -10 and -35 regions, while in archaea, the conserved promoter sequences include the TATA box, B recognition element sequence, and an initiator element.

Regulatory sequences, such as the bacterial Shine-Dalgarno sequence in the leader region upstream of the start codon, ensure the proper ribosome alignment.

Lastly, the terminator sequences downstream of the stop codon signal the end of transcription by forming stem-loop structures in the RNA or involving proteins like Rho.