Explanation: The β subunit of polymerase is thought to be its catalytic center. Studies suggested that the β subunit may contain two domains responsible for transcription initiation and elongation.

Explanation: A poly heparin has been shown to bind to the β’ subunit. Heparin inhibits transcription invitro and also competes with DNA for binding to polymerase.

Explanation: The β’ subunit of polymerase binds to two Zn2+ ions which are thought to participate in the catalytic function of the polymerase. It is also responsible for the binding of the enzyme to the template DNA.

Explanation: Binding of the σ factor converts the core RNA polymerase enzyme into the holoenzyme. The σ factor has a critical role in promoter recognition but is not required for transcription elongation.

σ28 is used for chemotaxis.

Explanation: The ω subunit of RNA polymerase helps in the association of all the subunits. Promoter binding is promoted by α subunit. Initiation and elongation is promoted by the β subunit. And β’ subunit binds to the Mg2+ cations.

Explanation: The σ subunit is not part of the RNA polymerase core enzyme. The RNA polymerase core protein has the structural formula of α2ββ’ω. Addition of the σ subunit converts the RNA polymerase core protein into a holoenzyme.

Explanation: The bacterial system has 3 RNA polymerases. They are RNA polymerase I, RNA polymerase II and RNA polymerase III. RNA polymerase I transcribes mRNAs, and RNA polymerases II and III transcribe the other specialized RNAs.