By Jack Szostak (HHMI/Harvard Medical School, and Massachusetts General Hospital)
Drawing the line between non-living and living in the steps leading to the emergence of life is often a subject of debate among scientists. In fact, the emergence of Darwinian evolution is often cited as a key aspect of the definition of life. Where would you draw this line in the steps leading to the emergence of life, as described by Dr. Szostak in his talk? In Dr. Szostak’s model of the emergence of cellular life on Earth, where would you say that natural selection or selective pressure played a role? http://www.tandfonline.com/doi/pdf/10.1080/073911012010524998
- According to Dr. Szostak’s model, which of the key steps leading from chemistry to biology took place in a spontaneous, random fashion?
- According to Dr. Szostak’s experimental evidence, which molecular and cellular processes could have presented selective advantages in the primitive Earth?
- Do you agree with Dr. Szostak that defining life does not serve the origin-of-life research field? Why or why not?
The Origin of Life on Earth
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Szostak begins his lecture with examples of the extreme environments in which life exists on Earth. He postulates that given the large number of earth-like planets orbiting sun-like stars, and the ability of microbial life to exist in a wide range of environments, it is probable that an environment that could support life exists somewhere in our galaxy. However, whether or not life does exist elsewhere, depends on the answer to the question of how difficult it is for life to arise from the chemistry of the early planets. Szostak proceeds to demonstrate that by starting with simple molecules and conditions found on the early earth, it may in fact be possible to generate a primitive, self-replicating protocell.
Early in his research career, Dr. Szostak made important contributions to the field of genetics. These included construction of the first yeast artificial chromosome and furthering our understanding of the function of telomeres, work for which he shared the Nobel Prize in Physiology or Medicine in 2009. By the 1990s, however, Szostak had redirected his research to understanding how life on earth may have first emerged. He began his studies in this area by attempting to construct an RNA molecule that could self-replicate. His lab now focuses on developing a simple artificial cell that can grow and evolve in response to a changing environment.
Szostak received his B.S. in biology from McGill University and his PhD in biochemistry from Cornell University. Currently, he is a Professor of Genetics at Harvard Medical School and an Investigator at Massachusetts General Hospital and the Howard Hughes Medical Institute.
- Jack Szostak iBioSeminar Part 2: Protocell Membranes
- Jack Szostak iBioSeminar Part 3: Non-Enzymatic Copying of Nucleic Acid Templates
- Kenneth Miller iBioMagazine: Evolution: Why it Matters