One disease affecting these structures is X-chromosome linked to mutations in the DKC1 gene and may require bone marrow transplants. Dyskerin helps to stabilize a catalytic complex that acts on this structure. Deficiencies in maintaining these structures, which are measured by the Q-FISH technique, (-5[1])are a major risk factor for idiopathic pulmonary fibrosis. Cajal bodies may serve to recruit RNA structures that act on these structures. The (-5[1])Hayflick limit (10[1])is based on the (10[1])length of these structures that can be extended (10[1])by TERT. (10[1])Shortened examples of these structures that lose their shelterin cap can trigger senescence, and these structures consist of repeating TTAGGG (10[1])motifs. For 10 points, what DNA sequences protect the ends of chromosomes? ■END■ (10[3])