One might think that identical-twin bacteria—clones of each other—would grow up and live very similarly. But a study published today in Science that examined individual bacterial cells in detail found that genetically identical E. Coli cells actually seem to express their genes quite differently, simply because of the random accidents of how their molecular machinery happens to operate.
“The paper is quite rich,” said Sanjay Tyagi, a molecular biologist at New Jersey Medical School who was not involved in the research [but published a perspectives piece on it]. “People think that if an organism has a particular genotype, it determines its phenotype [observable characteristics]–that there’s a one-to-one relationship,” said Tyagi. “But as it turns out, [differences in gene expression] can arise just from chance.” [The Scientist]