Two fascinating projects:
cells were very different when life began 3.5 billion to four billion years ago. Rather than small metropolises, they were more like a purse that carried instructions-consisting of just a membrane with genetic information inside. They lacked the structures and proteins that now make them tick. The question is: How then were they able to take in the nutrients necessary to survive and reproduce?
Harvard Medical School researchers report in Nature that they have built a model of what they believe the very first living cell may have looked like, which contains a strip of genetic material surrounded by a fatty membrane. The membranes of modern cells consist of a double layer of fatty acids known as phospholipids. But in designing a membrane for their cell, scientists worked with much simpler fatty acids that they believe existed on a primeval Earth, when the first cell likely formed. The key, says study co-author Jack Szostak, a Harvard geneticist, was to develop one porous enough to let in needed nutrients (such as nucleotides, the units that make up genetic material, or DNA) but strong enough to protect the genetic material inside and keep it from slipping out after replicating.
Lenski and his colleagues have witnessed a significant change. And their new paper makes clear that just because the odds of such a significant change are incredibly rare doesn’t mean that it can’t happen. Natural selection, in fact, ensures that sometimes it does. And, finally, it demonstrates that after twenty years, Lenski’s invisible dynasty still has some surprises in store.