Which best describes epigenetics?

Epigenetics fundamentally focuses on changes that affect gene expression without altering the underlying DNA sequence. This field investigates how various factors, such as environmental influences and lifestyle choices, can modify the way genes are turned on or off through chemical modifications like methylation and acetylation. These changes can have lasting effects on an organism’s phenotype, even though the genetic code remains unchanged.

This understanding is distinct from the study of DNA sequence changes, which pertains to mutations or alterations in the nucleotide sequence itself. Additionally, while exploring protein functions is an important aspect of biology, it does not directly relate to the core concept of epigenetics, which is concerned with gene expression mechanisms. Moreover, the exploration of evolutionary adaptations typically involves a broader examination of how traits evolve over time, rather than focusing specifically on the regulatory mechanisms behind gene expression. Thus, the answer that best captures the essence of epigenetics is the analysis of gene expression changes that do not involve alterations in the DNA sequence.