Final answer:
Epigenetics involves heritable changes in gene expression that do not alter the DNA sequence. Histone methylation, DNA methylation, and centromere determination are all epigenetic phenomena as they affect gene activity and inheritance through mechanisms outside of DNA sequence changes.
Step-by-step explanation:
Epigenetics refers to changes in gene expression that do not involve alterations to the underlying DNA sequence. These changes can affect how genes are turned on or off and are influenced by several factors, including environmental cues and lifestyle choices. Various processes such as histone methylation, DNA methylation, and centromere determination are classified as epigenetic because they result in modifications that can be passed down through cell division, affecting the genetic readout without altering the genetic code itself.
These mechanisms underscore the epigenetic principle that gene expression regulation can be heritable without changes to the DNA sequence, underlining the significant impact of epigenetics on development and inheritance, as well as its potential role in diseases like cancer.