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Hank brings us the story of Elizabeth Blackburn, the Nobel Prize-winning Australian woman who discovered telomeres and telomerase, and helped scientists begin to understand the process of aging at a genetic level.

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Of the 549 Nobel Prizes that have been awarded since 1901, only 16 have gone to women in science; and of those 16 prizes, three went to women in the Curie family. Which is great if you're a Curie, but still those 13 non-Curie women are representing 50 percent of humanity.

Fortunately, it was the life story of Marie Curie that inspired a young girl living in Australia in the 1950s named Elizabeth Blackburn to pursue a career in science. Since then, Blackburn has become one of the foremost authorities on the biology of life and death itself.

Blackburn was raised in Tasmania as the second of seven children whose mother, father, aunt and uncle were all family physicians. After a childhood of messing with ants and jellies and tadpoles, Blackburn wanted to study science, which wasn't always easy. The girls' school she attended didn't bother to teach physics, for instance. So, she had to go to a public high school at night to get the education she wanted.

After studying biochemistry in college she pursued graduate work in the then-pioneering field of DNA sequencing in the 1970s. Soon, she became interested in the mysterious mechanics behind cell division.

For a long time, nobody knew what kept our genetic information intact when our cells divided. Cell division requires all of the DNA in our chromosomes to be copied before it splits, and everybody thought that the copying process would leave each generation of chromosomes slightly shorter and more raggedy than the last.

But, while studying tiny, aquatic, protozoans called Tetrahymena, Blackburn and colleague Joseph Gall discovered that their chromosomes had repeating sequences of non-coding DNA at each end. When those little caps of DNA weren't there, they found the chromosome frayed apart as the cells divided. They discovered that these unique DNA sequences called telomeres were helping to protect the ends of the chromosomes.

Now telomeres didn't totally prevent the damage done to our DNA after quadrillions of replications, but they did help slow it down.

In humans at least, each time a cell divides, the telomeres get a little shorter, like a wick on a candle, and then when they're totally used up, the chromosomes are no longer protected and the cell dies.

This was a huge breakthrough in understanding how our cells, and therefore we, age and die. If you've got nice, long telomeres, your cells have a longer shelf-life, and by extension, so do you.

But this begged the question of where telomeres came from. Since proteins are made by enzymes, Blackburn and student Carol Greider continued to experiment on Tetrahymena, using tiny fragments of its DNA as kind of bait to lure out an enzyme that would repair them. 

And sure enough, on Christmas day 1994 Blackburn and Greider discovered telomerase, the enzyme that keeps cells from dying.

We're still learning how telomerase works in different organisms. In us, it seems our cells only produce it when we're embryos, but Blackburn and her colleagues discovered that telomerase also plays a key role in maybe the greatest threat to our longevity - cancer.

Cancer cells can ramp up the amount of telomerase the produce whenever they want, making them virtually immortal. Their telomeres never wear down, so they can multiply forever.
For all this ground breaking research, in 2009 Blackburn, Greider, and colleague Jack Szostak won the Nobel Prize for Physiology or Medicine for "the discovery of how chromosomes are protected by telomeres and the enzyme telomerase".

Since then, Blackburn has remained an outspoken advocate for women in science; for creative, curiosity driven search; and embryonic stem-cell research. She currently runs the Blackburn Lab at the University of California, San Francisco, where she continues to investigate telomeres and their role in human longevity. So I say carry on, Dr. Blackburn, carry on.

Thank you for watching this episode of SciShow: Great Minds. If you have ideas for other great minds you'd like us to profile, please leave those in the comments, or on Facebook or Twitter, and we'll see you next time.

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