Genetic instructions encoded in the DNA of the chromosome are copied, or transcribed, by enzymes called RNA polymerases (purple) into mRNAs (thin lines). These mRNA are then translated into proteins by ribosomes (depicted in gray). Moffitt et al. show that mRNAs that encode soluble proteins (orange) diffuse freely from the chromosome and are translated throughout the cytosol. Similarly, mRNAs that encode proteins that will be release into the periplasm or beyond (blue) are found throughout the cytosol. Membrane proteins (green) are insoluble in the cytosol and are instead translated at the inner membrane. The degradasome (yellow) is also found at the inner membrane and preferentially breaks down nearby mRNAs.