Both D-glucose and maltose (adisaccharide composed of two glucose residues) can be used ascarbon sources by Escherichia coli. However, D-glucose istaken up by an example of the sugar phosphotransferase system andmaltose is taken up by an example of an ABC transporter system.What are the differences between these systems? What are theirprotein components? What is the source of energy for accumulationof the sugar against a concentration gradient? In which form doesthe sugar appear in the cell?
