Group translocation is a mechanism used to transport substances into bacterial cells. As a molecule is moved against its concentration gradient into the cell, it is chemically modified, which prevents it from needing to be transported against an unfavorable gradient once inside. A common example is the bacterial phosphotransferase system, a series of carriers that phosphorylates sugars like glucose as they enter. Because this phosphorylation is already required during the early stages of sugar metabolism, the system is considered energy neutral.