Telomeres are the chromosomes end-part, that are needed to protect chromosome ends. Due to the way chromosomes are copied, these telomeres shorten with each round of cell division. This shortening is kept in check by the enzyme telomerase which elongates telomeres. However because of the limited amount of telomerase, telomere shorten with age in humans. People who cannot effectively elongate telomeres may show manifestations of a Telomere Syndrome, which include age-related diseases such as bone marrow failure, immune senescence and pulmonary fibrosis. Carol Greider, 2009 Nobel Laureate and professor at Johns Hopkins University, discusses how the seemingly benign structure on chromosome ends can underlie human disease. Series: "UC Berkeley Graduate Lectures" [Science] [Show ID: 28052]