【名师带你背单词】PTE高频内容精选《Twist in the tail of eukaryotic origins》part3,曼拓教育微信公众号文章

Dina老师

今天我们一起来看看这篇在PTE中听力考试中高频出现的生物类文章。

PTE练习题：Twist in the tail of eukaryotic origins Part3/3

关键词： eukaryotic, mitochondria

Dina老师

下面带着对这些单词和短语的理解，尝试读一读下面的原文，看看是不是容易理解的多了呢？

Bacteria take an open approach to sharing genetic information, so it’s possible that Midichloria picked up the genes from a distant relative that does carry a flagellum. To make sure that wasn’t the case, the team, led by Davide Sassera, also of the University of Milan, built an evolutionary tree incorporating Midichloria and a number of unrelated bacteria, using just the information in the flagella genes.

If Midichloria had obtained these genes from an unrelated bacteria, the two would have appeared to share a close evolutionary history. In fact, the tree placed Midichloria exactly where the team expected the Rickettsiales to be, confirming that the flagella genes must have been an ancient feature of this group. “Midichloria has hung on to these genes and everyone else in the group has lost them,” says Lo.

If the original mitochondrion also had a tail, it may have invaded an archaeon as a parasite – inadvertently creating the first eukaryote in the process, Lo adds. “We are changing the story.”

“The authors have made a compelling case for flagella being present in the lineage leading to mitochondria,” saysAnthony Poole of the University of Canterbury in Christchurch, New Zealand. “We need to think more broadly than a passive predator-prey scenario.”

Nick Lane at University College London agrees that the ancestral mitochondrion may have had a tail, but he is not convinced that it was a parasite. “Parasitic relationships don’t benefit the host cell,” he says.

Lo defends his position, however. “Many symbiotic relationships start as parasitism,” he says. “They give up fighting each other and then work together.”

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