Little did Greider know that her research as a 25-year-old graduate student at Berkeley would ultimately win her the 2009 Nobel Prize in Physiology or Medicine. While scientists knew that chromosomes were tipped like a shoelace, they did not know how these tips prevented chromosomes from unraveling during cell division. Greider and her colleagues, with whom she shares the Nobel, discovered a new enzyme, telomerase, that adds DNA to the ends, reducing the chances of mutations and lengthening the chromosomal lifespan. Their research catalyzed an eruption of studies connecting telomerase to cancer, anemia, age-related degenerative diseases, and other illnesses. Today Greider is a professor at the Johns Hopkins School of Medicine.