For MIT's Rudolf Jaenisch, It's All About Epigenetics

摘要

Genes have always received far more than the lion's share of credit for determining our physical characteristics-genotype determines phe-notype, as the old biological cliche has it. But genes aren't everything. Brain, liver, heart, skin, and nerve cells, just to name a few, all have the same set of genes-the same DNA in the chromosomes-and yet entirely different structures and functions. So why does the DNA of one cell direct it to become a neuron, while the DNA of another might preordain a skin cell, or a liver cell, or any other cell type in the human body?