FIGURE 12.5 Telomeres As shown in the drawing, telomeres are short, repeated DNA sequences that are found at the very tips of chromosomes (Epel, 2009b). In the photo, the telomeres are the fluorescent tips on the blue-stained human chromosomes. Like the plastic tips that protect shoelaces from fraying, telomeres protect the genetic data in the chromosomes from being broken or scrambled during cell division. With each cell division, the telomeres get shorter. However, an enzyme called telomerase can protect and even lengthen telomeres. Psychologists today are actively studying the environmental factors that affect telomere length, including behavioral interventions that increase telomerase activity (Blackburn & Epel, 2012; Jacobs & others, 2011).