PortalsOS

Eukaryotes are significant because they represent a singularity in the history of life on Earth, arising once about 2 billion years ago. This event gave rise to all complex life, despite bacteria and archaea having a greater genetic repertoire.

Nick Lane describes how the mitochondrial genome has shrunk over time from thousands of genes to just 37 in humans. This reduction is due to the inability to maintain a large genome within the confined environment of a cell.

The concept of extreme polyploidy in giant bacteria, where they possess tens of thousands of genome copies, highlights the immense energy demands compared to the efficiency of eukaryotic cells.

Bacterial evolution is fascinating because they maintain small genomes but have access to a large pan genome. For example, an E. coli cell might have 3,000 to 4,000 genes but access to 30,000 to 40,000 genes. This allows them to adapt by borrowing genes from other strains, which is crucial for survival in different environments.

The necessity of large genomes in multicellular organisms is driven by the need to minimize genetic conflict between cells, ensuring that all cells work towards the same goal of survival and reproduction.