Final answer:
A chromatin remodeling complex example is the SWI/SNF complex, which actively repositions nucleosomes to regulate gene expression by making DNA more or less accessible as needed, playing a role in processes including transcription and DNA repair.
Step-by-step explanation:
An example of a chromatin remodeling complex is the SWI/SNF complex. This complex uses energy derived from ATP hydrolysis to reposition and slide nucleosomes, which allows parts of the DNA to become more accessible for transcription, replication, or repair processes. Diseases like cancer can be associated with mutations in genes encoding the proteins that are part of these remodeling complexes.
These mechanisms are critical for regulating gene expression. When genes need to be expressed, chromatin remodeling aids in unwinding DNA at specific locations, allowing transcription factors and RNA polymerase access to DNA sequences. Conversely, tightening or condensation of chromatin into heterochromatin keeps sections of DNA inaccessible, resulting in gene silencing.