Читать книгу Algorithms in Bioinformatics - Paul A. Gagniuc - Страница 12

This chapter provides an overview of life and draws near some important questions: When did life on earth begin? What is life? How is it organized? When did multicellular organisms appear and why? How many species exist on Earth? Notions of biology related to the emergence and classification of life are discussed in connection with different strategies on organism formation. Some ultrastructural images (electron microscopy) are presented as examples for reference. The lower and upper physical dimensions of eukaryotic and prokaryotic organisms are explored in detail. The same exploration is made for viruses that interact within the kingdoms of life (Animalia, Plantae, Fungi, Protista, [Archaea and Bacteria] or Monera). Moreover, a discussion closely debates the reference system and the requirements for life; with special considerations for the “spark of metabolism.” Next, an introduction is made on some concrete topics, namely: The origins of eukaryotic cells, the endosymbiosis theory, the origins of organelles, the notion of reductive evolution, and the importance of horizontal gene transfer (HGT). Toward the end of the chapter, the main hypotheses regarding the origin of eukaryotic multicellularity are explored using the behavior observed in current species.