A3.1.10—Comparison of genome sizes

Genome size is the total amount of DNA in one haploid chromosome set. It can be compared across taxonomic groups, but a larger genome does not necessarily indicate a more complex organism.

Non-coding repeated DNA and polyploidy can increase genome size without adding a proportional number of functional genes. Database comparisons must therefore use consistent units and distinguish haploid from diploid measurements.

The Human Genome Project helped establish large-scale whole-genome sequencing. As sequencing has become faster and less expensive, current uses include studying evolutionary relationships and identifying genes or variants; a potential expanding use is personalized medicine.

A researcher can compare homologous genome sequences from several species, measure their sequence differences and use the pattern as evidence for closer or more distant evolutionary relationships.

A genome sequence provides data, not a diagnosis or treatment by itself. An interpretation must connect a validated genetic difference to evidence about function, ancestry or health.