Genome

Definition

The complete set of hereditary information encoded in the nucleotide sequence of DNA (or RNA in some viruses) within an organism, cell, or organelle. In eukaryotes, this includes the nuclear genome—comprising protein-coding genes, non-coding genes, regulatory sequences, and non-functional regions—plus any extranuclear genomes such as the mitochondrial genome found in nearly all animals and the chloroplast genome in plants and algae. The genome provides the genetic blueprint for development, physiology, and evolutionary potential.

Etymology

From German Genom, coined in 1920 by botanist Hans Winkler as a blend of gene and chromosome; the term entered English shortly thereafter.

Example

The genome of the fruit fly Drosophila melanogaster was one of the first complex eukaryotic genomes to be fully sequenced, revealing approximately 13,000 protein-coding genes that have made it a foundational model for understanding gene function, development, and evolutionary genetics in insects.

Synonyms

• genetic complement
• total DNA content

Related Terms

• Genotype
• phenotype
• mitochondrial DNA
• chloroplast DNA
• transcriptome
• proteome
• Chromosome
• gene
• Nucleotide
• sequencing
• comparative genomics
• population genomics

Usage Notes

Distinguished from genotype (the specific allelic composition at particular loci) and gene (a single functional unit). In arthropod research, 'genome' often implicitly refers to the nuclear genome unless specified otherwise, though mitochondrial genomes are frequently analyzed separately for phylogeography and species identification (DNA barcoding). The term carries no implication about whether the DNA is coding or functional; genomes contain substantial non-coding and often non-functional sequence. Plural 'genomes' is standard when comparing multiple species or individuals; singular with article ('the genome') typically denotes a reference assembly or the collective genetic material of a species.