Explore how this fascinating code shapes the living world.
This guide unlocks the mysteries of genomes and how they shape the living world.
What is a genome?
In short, think of your genome as your personal blueprint – the secret code that tells your body how to build you!
The genome refers to all the genetic material (i.e. DNA) present in the nucleus of a cell. The DNA which makes up the genome is an essential molecule that codes for life and can be thought of as a book of instructions containing all the information that an organism needs to grow and survive.
Genomes vary enormously in size between different species, with plants showing the greatest diversity of sizes (i.e. c. 2,500-fold).
Dr Ilia Leitch, Senior Research Leader at Kew
What’s the biggest genome?
The biggest genome belongs to New Caledonian fern species, found exclusively in New Caledonia and nearby Pacific islands where it makes its home on the trunks and branches of rainforest trees.
Stretched out, the Tmesipteris oblanceolata genome is taller than Big Ben’s tower in London. Dr Ilia Leitch explains, “it’s the biggest genome that has ever been discovered out of all organisms that live on this planet.”
The fern now holds three Guinness World Records for the largest genome, largest plant genome and largest fern genome.
For comparison, the human genome contains about 3.1 Gbp distributed across 23 chromosomes and when stretched out like a ball of yarn, the length of DNA in each cell only measures about 2m.
What’s the smallest genome?
The smallest genome belongs to a symbiotic bacterium called Carsonella ruddii, which lives off sap-feeding insects. This genome, researchers found, has just 159,662 ‘letters’ (or base pairs) of DNA and 182 protein-coding genes.
What’s the biggest genome in the animal world?
According to scientists the lungfish genome has the largest animal genome that has ever been deciphered. At 43 billion base pairs, it is 14 times larger than that of humans. This surpasses the genome of the axolotl, the previous record holder in the animal kingdom, by an impressive 30 percent.
Why is the genome so big?
Amazingly, the lungfish does not have significantly more genes than other vertebrates. But it has significantly more mobile genetic elements, so-called transposons. “These elements can be seen as a kind of computer viruses. They multiply on their own, but have no function. As a scientist, one is surprised that the lungfish’s ‘genetic hard drive’ has not long since crashed in view of the high number of transposons”, says Manfred Schartl.