Final answer:
The transition from a closed complex to an open complex in transcription does not require ATP; it is driven by the RNA polymerase binding to the promoter, leading to DNA unwinding and the start of mRNA synthesis.
Step-by-step explanation:
The transition from a closed complex to an open complex during transcription initiation does not require ATP. This process involves the RNA polymerase binding to the DNA promoter region, causing the DNA to unwind and form the transcription bubble needed for mRNA synthesis.
The initiation phase begins with the formation of the closed complex, where RNA polymerase binds to the promoter. Subsequently, the DNA helix unwinds without the need for ATP, forming an open complex that allows RNA polymerase to start synthesizing the mRNA molecule. The energy for this process comes from the breaking of the pyrophosphate (PP) into two inorganic phosphates, which occurs during the subsequent addition of ribonucleotide 5' triphosphates (NTPs) to the forming RNA chain, making the overall polymerization process energetically favorable.
The transition between the closed complex to the open complex in transcription does require ATP. The correct answer is option 1) Yes, it requires ATP and occurs due to the binding of RNA polymerase to the promoter region.
During transcription, RNA polymerase binds to the promoter region of the DNA and forms a closed complex. This closed complex then undergoes a conformational change in which the DNA strands unwind, forming an open complex. This conformational change requires ATP for the energy needed to separate the strands of DNA.