Final answer:
The core enzyme of RNA polymerase in prokaryotes consists of four subunits: a, a, ß, and B'. These subunits play different roles in the transcription process, with the o subunit being involved in initiation. When all five subunits are present, the holoenzyme is formed.
Step-by-step explanation:
The core enzyme of RNA polymerase in prokaryotes is composed of four subunits: a, a, ß, and B'. Each subunit has a unique role in the transcription process. The two a subunits are responsible for assembling the polymerase on the DNA, the ß subunit binds to the ribonucleoside triphosphate that will become part of the mRNA molecule, and the B' subunit binds the DNA template strand.
Additionally, there is a fifth subunit, called o, which is involved only in transcription initiation. This subunit is crucial for conferring transcriptional specificity so that the polymerase starts synthesizing mRNA from the appropriate initiation site.
The holoenzyme is formed when all five subunits are present, and it is responsible for transcribing genes in prokaryotes.