Final answer:
Epigenetic inheritance can involve chromatin remodeling, histone modification, and DNA methylation, all of which affect gene expression and can be influenced by environmental factors.
Step-by-step explanation:
Three categories of modification that contribute to epigenetic inheritance include:
- Chromatin remodeling: This process changes the arrangement of chromatin, making DNA either more or less accessible for transcription. Environmental factors can promote chromatin to relax from the tightly packed 30nm fiber to a more accessible 10nm 'beads-on-a-string' structure. An example includes the influence of UV exposure on gene expression.
- Histone modification: Post-translational modifications of histone proteins, such as acetylation and methylation, influence DNA packaging. These modifications can activate or repress gene expression by altering how tightly the DNA is wound around histones.
- DNA methylation: The addition of methyl groups to DNA, usually at cytosine bases, typically suppresses gene transcription. This alteration can be hereditary as methylation patterns may persist through cell division.
Each of these modifications can occur in response to environmental stimuli and play a significant role in regulating gene expression without altering the underlying DNA sequence, making them key components of epigenetic regulation.