Chromatin remodeling complexes function primarily to ______.

• A. Degrade histones
• B. Expose DNA by repositioning nucleosomes
• C. Synthesize RNA
• D. Replicate DNA

Answer: (B)

Chromatin remodeling complexes use energy from ATP to alter how DNA is wrapped around histones. By repositioning, sliding, or occasionally evicting parts of the nucleosome, they change the accessibility of DNA. When a promoter or regulatory sequence is moved into a more open position, transcription factors and RNA polymerase can bind and initiate transcription. That exposure of DNA through nucleosome repositioning is the core action of these remodelers.

This isn’t about destroying histones or making RNA or copying DNA. Degrading histones isn’t their primary role, and synthesis of RNA or replication of DNA are carried out by dedicated enzymes involved in transcription and DNA replication, not chromatin remodelers.