How do bacteria respond to environmental challenges and signals so quickly and effectively? In addition to genetic modifications there are a series of non genetic, or epigenetic, modifications. Genetic modifications change the sequence of nucleotides that, for instance, comprise a protein-coding gene. In that case the resulting protein is modified to better handle the environmental challenge. Epigenetics, on the other hand, involves various other types of modifications. For instance, the three-dimensional structures of proteins may be dramatically altered, or tiny chemical signals—methyl groups—may be added to certain proteins or DNA sequences. As with genetic modifications, many of the epigenetic modifications are heritable, so the adjustments are passed on to later generations. Read more