Telomeres are large nucleoproteins structures that cap the ends of chromosomes in eukaryotic cells. When a cell divides, a small portion of the telomere is lost due to the inherently incomplete process of genome replication. If left unchecked, over time the telomeres will reach a critically short length and the cell will face genomic instability, deterioration or death. To offset this shortening, an essential enzyme called telomerase rebuilds the telomeres by synthesizing new telomeric DNA repeats at chromosome ends. Kelly Nguyen's group, in the LMB's Structural Studies Division, has solved the first complete atomic model of this enzyme and discovered a histone dimer as novel telomerase subunits.