Almost none of your genome is genes
About one to two percent of the human genome codes for proteins. The rest is regulatory sequence, introns, and a great deal of repeats.
Established2 min read
The draft human genome made the count public. Protein-coding exons are a thin slice. Introns interrupt the genes. Transposons and their wreckage, LINEs and SINEs and Alu elements, are nearly half the assembly. A gene is a small island.
‘Junk’ was always a hypothesis about function, not a description of the sequence. ENCODE later showed widespread biochemical activity — transcription, binding — which is not the same as natural selection caring. The percentage that codes for protein is the settled, small number. What the rest is for is a longer argument.
Caveats
- One to two percent is protein-coding sequence, not ‘the only functional DNA’.
- The precise percentage moves slightly with gene annotation. It does not become a majority.
Sources
- 1International Human Genome Sequencing Consortium. Initial Sequencing and Analysis of the Human Genome. Nature 409, 2001.