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Updated: May 22, 2026
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Hi-C: A Method to Study the Three-dimensional Architecture of Genomes.
Published on: May 6, 2010
The energetics of genome complexity
1Department of Genetics, Evolution and Environment, University College London, Gower Street, London W1E 6BT, UK. nick.lane@ucl.ac.uk
Nature
|October 22, 2010
Summary
The evolution of complex life depended on the origin of eukaryotic cells from prokaryotes. Mitochondrial endosymbiosis enabled a massive increase in gene expression, driving eukaryote complexity.
Area of Science:
- Cell biology
- Evolutionary biology
- Genomics
Background:
- All complex life originates from eukaryotic cells, which evolved once from prokaryotes.
- Prokaryotes exhibit limited evolutionary progression towards complexity.
- The reasons for prokaryotic evolutionary constraints are not fully understood.
Purpose of the Study:
- To investigate the bioenergetic and genomic factors limiting prokaryotic complexity.
- To elucidate the role of endosymbiosis in the evolution of eukaryotic cells and complexity.
Main Methods:
- Comparative genomics analysis.
- Bioenergetic modeling.
- Evolutionary pathway reconstruction.
Main Results:
- Prokaryotic genome size is fundamentally constrained by bioenergetic limitations.
- Mitochondrial endosymbiosis dramatically altered DNA distribution relative to energy-producing membranes.
- This restructuring allowed a 200,000-fold increase in gene expression capacity, dependent on mitochondrial energy.
Conclusions:
- Mitochondrial endosymbiosis was a critical innovation, enabling the genomic expansion necessary for eukaryotic complexity.
- The availability of mitochondrial power was a prerequisite for the evolution of complex life and multicellularity.
Related Concept Videos
00:58Genomic DNA in Eukaryotes
Eukaryotes have large genomes compared to prokaryotes. To fit their genomes into a cell, eukaryotic DNA is packaged extraordinarily tightly inside the nucleus. To achieve this, DNA is tightly wound around proteins called histones, which are packaged into nucleosomes that are joined by linker DNA and coil into chromatin fibers. Additional fibrous proteins further compact the chromatin, which is recognizable as chromosomes during certain phases of cell division.
00:58DNA Packaging
Overview
03:21Genome Size and the Evolution of New Genes
While every living organism has a genome of some kind (be it RNA, or DNA), there is considerable variation in the sizes of these blueprints. One major factor that impacts genome size is whether the organism is prokaryotic or eukaryotic. In prokaryotes, the genome contains little to no non-coding sequence, such that genes are tightly clustered in groups or operons sequentially along the chromosome. Conversely, the genes in eukaryotes are punctuated by long stretches of non-coding sequence.
02:21Chromatin Packaging
Each human somatic cell contains 6 billion base-pairs of DNA. Each base-pair is 0.34 nm long, which means that each diploid cell contains a staggering 2 meters of DNA. How is such a long DNA strand packed inside a nucleus measuring only 10 - 20 microns in diameter?
The chromatin
In combination with specialized DNA binding protein called Histones, the DNA double helix forms a compact DNA: protein complex called chromatin. The chromatin itself is further compacted into higher-order structures.
The chromatin
In combination with specialized DNA binding protein called Histones, the DNA double helix forms a compact DNA: protein complex called chromatin. The chromatin itself is further compacted into higher-order structures.
03:21Genome Size and the Evolution of New Genes
While every living organism has a genome of some kind (be it RNA, or DNA), there is considerable variation in the sizes of these blueprints. One major factor that impacts genome size is whether the organism is prokaryotic or eukaryotic. In prokaryotes, the genome contains little to no non-coding sequence, such that genes are tightly clustered in groups or operons sequentially along the chromosome. Conversely, the genes in eukaryotes are punctuated by long stretches of non-coding sequence.
01:32Chromatin Packaging
Each human somatic cell contains 6 billion base pairs of DNA. Each base pair is 0.34 nm long, meaning each diploid cell contains a staggering 2 meters of DNA. This long DNA strand is packed inside a nucleus measuring only 10-20 microns in diameter with the help of specialized DNA-binding proteins called histones. Together they form a compact DNA-protein complex called chromatin. The chromatin is further compacted into higher-order structures. The highest level of compaction is achieved during...