How many RNA polymerases do prokaryotes possess?

Prokaryotes possess a single type of RNA polymerase. This enzyme is responsible for the synthesis of all types of RNA in prokaryotic cells, including messenger RNA (mRNA), ribosomal RNA (rRNA), and transfer RNA (tRNA). The structure of prokaryotic RNA polymerase is relatively simple compared to its eukaryotic counterparts, which have multiple RNA polymerases specialized for different types of RNA synthesis.

In prokaryotic cells, the RNA polymerase is made up of a core enzyme that consists of four subunits (two alpha, one beta, and one beta prime) and a sigma factor that helps the enzyme recognize promoter regions to initiate transcription. Once the transcription process begins, the sigma factor is released, allowing the core enzyme to elongate the RNA strand.

This single RNA polymerase capability reflects the streamlined nature of prokaryotic cells, which do not compartmentalize their cellular processes as eukaryotes do, where multiple RNA polymerases serve distinct functions in different cellular compartments.