cover of episode LUCA, the Last Universal Common Ancestor

LUCA, the Last Universal Common Ancestor

2024/11/22
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Discover Daily by Perplexity

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Alex: 本期节目探讨了 LUCA(最后共同祖先),一个生活在大约 42 亿年前的单细胞生物,是地球上所有生命的共同祖先。LUCA 并非简单的生物,它拥有复杂的细胞机制,包括一个先进的免疫系统,拥有 19 个 CRISPR 基因,可以防御远古病毒,这表明即使在生命早期,生物战争就已经存在。LUCA 出现于地球的冥古宙时期,这是一个极其恶劣的环境,地表温度勉强能够维持液态水,陨石频繁撞击地球,火山活动剧烈,大气中没有氧气,而是充满了氢气、甲烷和氨气。然而,在如此极端的环境下,生命不仅出现了,而且发展出了复杂的特征。LUCA 的细胞结构非常复杂,拥有脂质双层膜和含水的细胞质,DNA 作为其遗传信息储存系统。它在热液喷口附近生存,通过将二氧化碳和氢转化为有机化合物来获取能量,这种被称为产乙酸作用的过程,一些现代细菌至今仍在使用。LUCA 的发现具有深远意义,它表明在合适的条件下,即使在极端环境中,复杂的生命也能相对快速地发展。这对于寻找地球以外的生命具有重要意义,尤其是在可能与 LUCA 生存环境相似的环境中。LUCA 生存在一个复杂的生态系统中,与其他微生物和病毒共存,这表明生物多样性出现的时期比之前认为的要早得多。这挑战了我们对早期生命简单或原始的假设。复杂免疫系统和代谢途径的存在表明,关键的生物创新出现在生命历史的早期。LUCA 的故事不仅关乎我们的过去,也重塑了我们寻找宇宙生命的方式,提醒我们生命的起源比我们以前想象的要复杂得多。

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In this episode of Discover Daily, we explore LUCA, the Last Universal Common Ancestor. Scientists have dated this single-celled organism from which all modern life descends, to 4.2 billion years ago - just 400 million years after Earth's formation. This ancient organism possessed remarkable complexity, including 2,600 protein-coding genes, a sophisticated immune system with 19 CRISPR genes, and the ability to perform complex metabolic processes near hydrothermal vents in Earth's earliest oceans. Despite living during Earth's most violent period, when the planet was bombarded by meteorites and dominated by volcanic activity, LUCA thrived in an environment without oxygen, converting carbon dioxide and hydrogen into energy. Its genome was comparable in size to modern bacteria, challenging our understanding of how quickly complex life can develop. LUCA existed within a diverse ecosystem alongside other microbes and viruses, suggesting that biological diversity emerged much earlier than previously thought.Recent genetic analysis reveals that LUCA's cellular machinery, while simpler than modern organisms, established the fundamental blueprint for all life on Earth. This discovery has significant implications for the search for extraterrestrial life, suggesting that complex organisms might emerge quickly under suitable conditions. Understanding LUCA's ancient immune system and metabolic pathways could also lead to new approaches in fighting disease and developing industrial processes.From Perplexity's Discover Feed):https://www.perplexity.ai/page/the-last-universal-common-ance-F_o_WexZSEmFZFKgVykYzQ)

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