Reminder of the differences between prokaryotic and eukaryotic cells

Since the publication in 1962 of “The concept of a bacterium” by RY Stanier (1916-1982) and CB Van Niel (1897-1985), it has become classic to divide the cellular world into two large groups: the nucleus-less prokaryotes and eukaryotes with nucleus, following a terminology previously defined by the French biologist Edouard Chatton (1883-1947). Since then, the work of Carl Woese (1928-2012) led in 1977 to the division of prokaryotes into two distinct lineages: eubacteria and archaea. Although these two lineages are made up of cells devoid of a nucleus, the differences in their structure and function are such that biologists make them two distinct areas of the living world. This world is therefore no longer divided into animals/plants, but into eubacteria/archaea/eukaryotes. Each of these three domains has its own characteristics but specifically shares several particularities with each of the other two (Table 1). Nevertheless, eukaryotic cells have a much higher complexity than eubacteria and archaea, so the prokaryotic/eukaryotic distinction is still valid and we will follow it in this book. To name just two characteristics: a eukaryotic cell is on average 10,000 times larger than a prokaryotic cell. In addition, the evolution of the eukaryotic cell has led to the emergence of complex multicellular organisms, which prokaryotic cells did not really produce. Two questions therefore arise: how did the eukaryotic cell appear and what are the kinship relationships it maintains with prokaryotic-type cells? To answer these questions, it is first necessary to better understand the differences between eukaryotic and prokaryotic cells, which are not restricted to the presence/absence of a nucleus alone.

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