Final answer:
The most common form of gene expression control is at the level of transcription initiation.However, transcription initiation is the most common control point where a gene is turned on or off through interactions of transcription factors with DNA.
Step-by-step explanation:
The most common form of gene expression control point is at the level of transcription initiation.
Regulation of gene expression can occur at multiple levels, including epigenetic, transcriptional, post-transcriptional, translational, and post-translational.
However, transcription initiation is the most common control point where a gene is turned on or off through interactions of transcription factors with DNA.