how is it possible that two people with the same genes and raised alike can be so different?
nature and nurture
nature
your genes, gives you traits for eye color, hair color, blood type
nurture
based on your lifestyle and environment, including diet, rearing, and education
what is the bridge between nature and nurture?
epigenetics
where do identical twins come from?
a single fertilized egg that splits in two, their genes are the same
what are specific chemical reactions, or epigenetic "tags" associated with?
DNA methylation in which a methyl group attaches to the cytosine base of DNA
what happens when a methyl group attaches to the cytosine base of DNA?
the methyl group interferes with transcription factors and other proteins in the transcription machinery, thereby silencing or weakening a gene. over time, the differences in these tags accumulate, making twins increasingly different from each other.
what are epigenetics?
heritable changes in gene expression without changing the DNA sequence
what do chemical reactions due to environmental exposure influence?
how genes are turned off or on, how they are weakened or strengthened, how they can change our immune systems, and how they build muscle, brains and all other body parts
why do twins have gradual differences?
assuming they have a similar upbringing it can be attributed to disparate control of genes
why do epigenetics have an important implication for medicine?
the appearance of tags on genes help scientists discover the cause of some illnesses that cannot be explained by DNA or genetic mutation alone
what has been shown to have different DNA methylation on certain genes?
identical twins discordant for autism, psychiatrique disorders, and cancer
are epigenetic changes reversible?
yes