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Most eukaryotes are diploid, meaning that there are two of each chromosome in the nucleus but the 'genome' refers to only one copy of each chromosome. Some eukaryotes have distinctive sex chromosomes, such as the X and Y chromosomes of mammals, so the technical definition of the genome must include both copies of the sex chromosomes.
The OED suggests that its third definition originated as a back-formation from mitome, [7] Early attestations include biome (1916) [8] and genome (first coined as German Genom in 1920 [9]). [10] The association with chromosome in molecular biology is by false etymology.
Genomics is an interdisciplinary field of molecular biology focusing on the structure, function, evolution, mapping, and editing of genomes. A genome is an organism's complete set of DNA, including all of its genes as well as its hierarchical, three-dimensional structural configuration.
The term was first used by Davis in 1949, "We here propose the name phenome for the sum total of extragenic, non-autoreproductive portions of the cell, whether cytoplasmic or nuclear. The phenome would be the material basis of the phenotype, just as the genome is the material basis of the genotype." [10]
Genomics is the field of genetics concerned with structural and functional studies of the genome. [1] A genome is all the DNA contained within an organism or a cell including nuclear and mitochondrial DNA. The human genome is the total collection of genes in a human being contained in the human chromosome, composed of over three billion ...
The most commonly used approach to genome-investigation is evolutionary genomics biology, or evo-geno, in which the genomes of two species which share a common ancestor are compared. [4] A common example of evo-geno is comparative cognitive genomics testing between humans and chimpanzees which shared an ancestor 6-7 million years ago. [5]
A speciation event produces orthologs in the two daughter species (human and chimpanzee). Bottom: in a separate species , a gene has a similar function (histone-like nucleoid-structuring protein) but has a separate evolutionary origin and so is an analog. One level of genome organization is the grouping of genes into several gene families.
Ecological genetics is the study of genetics in natural populations. It combines ecology, evolution, and genetics to understand the processes behind adaptation. [1] It is virtually synonymous with the field of molecular ecology.