Final answer:
The cell determines if chromatin should be open or closed through a process called chromatin remodeling. If a gene is to be transcribed, the chromosomal region encoding that gene undergoes modifications that open the promoter region, allowing for gene transcription.
Step-by-step explanation:
The cell determines whether chromatin should be open or closed through a process called chromatin remodeling. Chromatin remodeling involves altering the structure of chromatin to make it accessible or inaccessible for gene transcription. If a gene is to be transcribed, the histone proteins and DNA in the chromosomal region encoding that gene are modified in a way that opens the promoter region and allows RNA polymerase and transcription factors to bind and initiate transcription. If a gene is to remain turned off, the histone proteins and DNA have different modifications that signal a closed chromosomal configuration, blocking the binding of transcription factors and preventing transcription.