Elizabeth Helen Blackburn, AC FRS FAA FRSN (born 26 November 1948) is an Australian-American Nobel laureate who is the former President of the Salk Institute for Biological Studies. Previously she was a biological researcher at the University of California, San Francisco, who studied the telomere, a structure at the end of chromosomes that protects the chromosome. In 1984, Blackburn co-discovered telomerase, the enzyme that replenishes the telomere, with Carol W. Greider. For this work, she was awarded the 2009 Nobel Prize in Physiology or Medicine, sharing it with Greider and Jack W. Szostak, becoming the only Tasmanian-born Nobel laureate. She also worked in medical ethics, and was controversially dismissed from the Bush Administration's President's Council on Bioethics.