Final answer:
Epigenetic inheritance involves reversible chemical modifications to DNA or histones, affecting gene expression without altering DNA sequence. These modifications regulate chromatin structure, are heritable through cell divisions, and can be influenced by environmental factors, potentially impacting subsequent generations.
Step-by-step explanation:
The form of epigenetic inheritance described involves non-permanent, chemical modifications to segments of nuclear DNA, which subsequently alter gene expression. Key epigenetic mechanisms include histone modification, such as acetylation and methylation, and DNA methylation. These modifications can change the structural configuration of chromatin, making it either more condensed or more relaxed, and thus influence whether genes are active or silenced. The changes can be passed down through cell division and sometimes through generations, though they are not changes to the actual DNA sequence.
For instance, DNA methylation often correlates with decreased gene expression. On the other hand, modifications to histones can either decrease or increase accessibility of DNA to transcriptional machinery, depending on the type of modification. Epigenetic regulation is essential in development, allowing cells to differentiate and give rise to various tissues and organs through specific gene expression patterns that are inherited by daughter cells after mitosis.
Environmental factors can also play a role, impacting epigenetic changes which in turn can affect not just an individual's gene expression but potentially those of future generations. These discoveries have profound implications, suggesting behaviors such as diet, smoking, and exposure to toxins can leave an epigenetic legacy that extends beyond a single lifespan.