Genomic editing leads to irreversible changes to the genome. There are ~5000 genes in the genome. Primary sequencing of the maize genome was completed in 2008. The complete mouse reference genome was sequenced in 2002. The globe artichoke genome has been sequenced. One approach of inserting foreign genes into the "Drosophila" genome involves P elements. There are five chromosomes per the haploid genome. Mutations are changes in the DNA sequence of a cell's genome. There are a number of techniques used to insert genetic material into the host genome. FlyBase annotates the entire "Drosophila melanogaster" genome. These procedures allow differentiation of the repeated sequences within the genome. Poliovirus is composed of an RNA genome and a protein capsid. Recombination in RNA viruses appears to be an adaptation for coping with genome damage. Noncoding sequences make up 98% of the human genome. The same mechanism holds true for silencers in the eukaryotic genome.