[Campbell Biology P.422] Based on Figure 18.9 and the accompanying text, where are 'control ... | Practice Question

Based on Figure 18.9 and the accompanying text, where are 'control elements' primarily located relative to the gene, and what is their general role?

  • A: Only upstream of the promoter, serving as binding sites for RNA polymerase II.
  • B: Both near (proximal to) and far from (distal to) the promoter, acting as binding sites for transcription factors that regulate transcription initiation.
  • C: Only within exons, determining the start and stop codons for translation.
  • D: Exclusively downstream of the poly-A signal sequence, indicating where the transcript terminates.

Explanation

The text states that 'A number of control elements gold are involved in regulating the initiation of transcription; these are DNA sequences located near proximal to or far from distal to the promoter.' Figure 18.9 visually represents both 'Enhancer group of distal control elements ' and 'Proximal control elements'. Their role is to serve as binding sites for transcription factors that regulate transcription.