Elizabeth Helen Blackburn (born 26 November 1948) is an Australian-American biological researcher at the University of California, San Francisco, who studies the telomere, a structure at the end of chromosomes that protects the chromosome. Blackburn co-discovered telomerase, the enzyme that replenishes the telomere. For this work, she was awarded the 2009 Nobel Prize in Physiology or Medicine, sharing it with Carol W. 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.She won American Institute of Chemists Gold Medal in 2012.