Precisely why Eukaryotic Genome Are generally Consequently Significant
To express that the eukaryotes have large genomes, one should be comparing them to organisms with much smaller genomes, the prokaryotes. It’s the analysis between these organisms which will give conclusive evidence as to why the eukaryotes have large genomes.
Immediately one jumps to the proven fact that the eukaryotes are far more complex and therefore they have to have a bigger genome, where would inevitably produce more genes. This really is obviously true, though the complexity of the genome doesn’t directly correspond to a rise in genome size. Wheat features a far larger genome than ours however, one would hesitate to call them more complex. genoma Therefore, there must be more subtle underlying reasons why the eukaryotes have such large genomes.
Transposable elements increase the size of genomes by copying and inserting into different parts of the genome. However, transposable elements also occur in the prokaryotes and the affect of the transposons on eukaryotes in increasing the size of the genome is probably negligible. One reason why the affect of transposons isn’t always detrimental to the organism is due to the introns contained in a eukaryote. The gene rich DNA of the prokaryotes is in sharp contrast to genes scattered around eukaryotic genomes. The introns in the eukaryotic genome make sure they are much, much larger than in the prokaryotes. The gene number difference in eukaryotes is all about 10 fold whereas the beds base pair number can be 1000 fold bigger. The question therefore lies within the introns of the eukaryotes. Why exist so many introns in the eukaryotic genome; giving rise to its ‘large size’?
As the eukaryotes evolved from the prokaryotes one must elucidate the purpose of the introns in the eukaryotes as, say a barrier (against transposons, mutation etc). However, this may be construed to truly have the same equally beneficial properties in prokaryotes. A better approach would be to analyse the power output. Prokaryotes use 25% of their energy production in DNA copying and maintenance (the other 75% being that of protein production). Therefore, any increase in size of the DNA in prokaryotes would be too costly for the organisms to keep and replicate and thus the DNA is stripped right down to an extremely gene rich molecule. Eukaryotes are profligate in pouring energy to their genomes (due to their greater energy production capacity as a direct consequence of experiencing specific organelles devoted to this purpose) and as a result they are able to afford to be so disgracefully inefficient and allow accumulation of introns.
Another and probably the most important consequence of being able to pour large levels of energy in to the genome is that eukaryotes can allow gene duplication events, which produce proteins that differ very slightly. Not merely this, but in plants especially, entire duplication of genomes and addition of different divergent genomes are commonplace within that kingdom. Giving these organisms such huge genomes.