Epigenetics
Epigenetics
For decades it was believed that only the inherited DNA sequences determined an organism’s genetic make-up. Now it appears that chemicals piggy-backing on the DNA molecule can alter its function.
Learning Objective: Describe what epigenetics is and how environmental factors can impact DNA expression.
Iris color in human eyes is complex. Multiple genes impact production of different forms of melanin pigment. However, even taking multiple genes and their various allele versions into account, something else seems to be impacting the pattern and variation of pigments in the iris. Researchers wonder; could this be yet another example of epigenetics in action?
The paradigm shift from the widely accepted theory that only the bases of A-T-C-G in DNA determine inheritance to the epigenetic idea that chemicals piggy-backing on the DNA are inherited as well is re-writing genetics.
In some carpenter ant species, worker ants and the queen can be genetically identical, but have different shapes, sizes, and behaviors. Epigenetic factors, including DNA methylation and histone modification may alter gene expression.
If you take the eggs of mutant Drosophila melanogaster with white eyes and briefly heat the eggs, the adults will have red eyes instead of white eyes. O.K., that could be something to do with the heat impacting protein synthesis, but then it gets weird…
If these flies are again crossed, the following generations have mostly white eyes, but also some red eyes, even though the alleles of DNA passed on are all white eye recessive sequences. This suggests that something more than DNA is impacting phenotypes.
The potential impact of chemicals attaching to DNA will have to be taken into account when trying new genetic technologies, including cloning.
Epigenetics and Cloning
A concern with reproductive cloning is that chemical “bookmarks” may not be scrubbed from the donor chromosomes sufficiently; leading to premature aging of cloned offspring.
This video introduces the basics of reproductive cloning.
Watch this video; you can select the closed captioning “cc” option if you would like to see the text.
The next section is a look at a structure found in most animals: some sort of eye that receives light information.
Check your knowledge – Epigenetics
Review your notes. Can you explain why epigenetics is such a significant shift in understanding inheritance? If so, move forward to the next page.
Learning Objective:
Describe what epigenetics is and how environmental factors can impact DNA expression.
Go back to the Laboratory Animals Page
Go forward to the Eyes Page
Genomes Contents
Complete all five of these sections before taking the quiz and submitting your media piece.
This Module
8: Why does it look like this?
This Guide
8B: Genomes
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8B: Quiz & Media
