Figure 24.1 Glycogen. (A) Glucose units joined by α-1,4 linkages are shown as straight lines. The nonreducing ends of the glycogen molecule form the surface of the glycogen granule. At the core of the glycogen molecule is the protein glycogenin (yellow, Chapter 25). Degradation takes place at this surface. (B) A cross section of a glycogen molecule shows the branching caused by the α-1,6 linkages. The glycogenin is identified as G.