What are the chemical modifications added to DNA or histone proteins that regulate gene expression called?

The term that describes the chemical modifications added to DNA or histone proteins, which play a crucial role in regulating gene expression, is epigenetic tags. These tags do not change the underlying DNA sequence but alter how genes are expressed and can influence cellular functions. Common types of epigenetic modifications include DNA methylation and histone acetylation, which can either promote or repress the transcription of specific genes.

These modifications are essential in processes such as development, differentiation, and response to environmental signals. They can be inherited through cell division, providing a mechanism for the regulation of gene expression across generations. Understanding epigenetic tags is fundamental to studying how genes are turned on or off in different contexts, which is key in areas like cancer research, developmental biology, and genetics.

The other options do not capture the full scope of these regulatory modifications. Chromatin remodelers refer to complexes that alter the structure of chromatin, histone modifications are a subset of epigenetic tags specifically concerning histone proteins, and transcription factors are proteins that bind to DNA to influence transcription but do not refer to chemical modifications.