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Multiple Choice
Which of the following is required for the initiation of RNA synthesis during transcription in prokaryotes?
A
DNA ligase
B
RNA polymerase holoenzyme (core enzyme plus sigma factor)
C
Ribosomes
D
DNA helicase only
Verified step by step guidance
1
Understand the process of transcription in prokaryotes: Transcription is the process by which RNA is synthesized from a DNA template. It involves several steps, including initiation, elongation, and termination.
Identify the key enzyme involved in transcription: RNA polymerase is the enzyme responsible for synthesizing RNA by reading the DNA template strand.
Learn about the RNA polymerase holoenzyme: In prokaryotes, the RNA polymerase holoenzyme consists of the core enzyme (responsible for RNA synthesis) and the sigma factor (which helps the enzyme recognize and bind to the promoter region of the DNA).
Understand the role of the sigma factor: The sigma factor is essential for the initiation of transcription because it guides the RNA polymerase to the correct starting point on the DNA (the promoter). Once transcription begins, the sigma factor is released.
Eliminate incorrect options: DNA ligase is involved in DNA replication and repair, not transcription. Ribosomes are involved in translation, not transcription. DNA helicase unwinds DNA during replication, but in transcription, the RNA polymerase itself unwinds the DNA locally. Therefore, the correct answer is RNA polymerase holoenzyme.