alleryStart learning →How many protein subunits make up the core enzyme of prokaryotic RNA polymerase?
ATwo subunits
BThree subunits
CFour subunits
DFive subunits
Answer & Solution
Correct answer: C. Four subunits
1. The prokaryotic polymerase has five polypeptide subunits in total, two of which are identical.
2. Four of them form the core enzyme, the complex that carries out elongation.
3. The fifth is the sigma protein, which assists only with initiation.
4. Counting all five gives the holoenzyme, so five is the trap for a question that asks about the core.
_Source: OpenStax Biology (1st ed., CC BY 4.0), Ch 15 "Genes and Proteins", section 15.2 Prokaryotic Transcription_
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