_____ proteins bind _____, and they work to decrease transcription.

_____ proteins bind _____, and they work to decrease transcription.

• A. Activators; Enhancers
• B. Silencers; Enhancers
• C. Repressors; Silencers
• D. Transcription factors; Promoters

Answer: (C)

Transcriptional control happens when proteins bind DNA elements to modulate RNA polymerase activity. A repressor protein binding to a silencer is the classic setup that lowers transcription. Silencers are DNA sequences that recruit repressors (and often corepressors or chromatin-remodeling factors) to make the gene less accessible or to block transcription machinery, so gene expression drops. Why this fits best: the goal described is to decrease transcription, and a repressor–silencer interaction directly accomplishes that by opposing the transcriptional machinery. Why the other pairings don’t fit: activators binding to enhancers typically increase transcription, not decrease it; silencers refer to DNA elements rather than proteins, so “silencers” as the binding proteins doesn’t describe a protein–DNA interaction that reduces transcription; transcription factors binding promoters generally relate to initiation, and while some can repress, the common positive association with promoters is activation or initiation rather than repression via a silencer.

Transcriptional control happens when proteins bind DNA elements to modulate RNA polymerase activity. A repressor protein binding to a silencer is the classic setup that lowers transcription. Silencers are DNA sequences that recruit repressors (and often corepressors or chromatin-remodeling factors) to make the gene less accessible or to block transcription machinery, so gene expression drops.

Why this fits best: the goal described is to decrease transcription, and a repressor–silencer interaction directly accomplishes that by opposing the transcriptional machinery.

Why the other pairings don’t fit: activators binding to enhancers typically increase transcription, not decrease it; silencers refer to DNA elements rather than proteins, so “silencers” as the binding proteins doesn’t describe a protein–DNA interaction that reduces transcription; transcription factors binding promoters generally relate to initiation, and while some can repress, the common positive association with promoters is activation or initiation rather than repression via a silencer.