Editing Mouse (section)

=== As experimental animals ===
{{Main|Laboratory mouse}}
[[File:Fatmouse.jpg|thumb|[[Knockout mouse]] (left) and normal mouse (right)]]

Mice are common [[experiment]]al animals in laboratory research of [[biology]] and [[psychology]] fields primarily because they are [[mammal]]s, and also because they share a high degree of [[homology (biology)|homology]] with humans. They are the most commonly used [[mammal]]ian [[model organism]], more common than [[rats]]. The mouse [[genome]] has been sequenced, and virtually all mouse [[gene]]s have human [[Homologous chromosome|homologs]]. The mouse has approximately 2.7 billion base pairs and 20 pairs of chromosomes.<ref>{{cite web|url=https://www.genome.gov/10002983/2002-release-draft-sequence-of-mouse-genome/|title=2002 Release: Draft Sequence of Mouse Genome|access-date=15 August 2016}}</ref>
They can also be manipulated in ways that are illegal with humans, although [[animal rights]] activists often object. A [[knockout mouse]] is a [[genetically modified mouse]] that has had one or more of its genes made inoperable through a [[gene knockout]].  Experimental mouse model systems include [[mouse model of colorectal and intestinal cancer|mouse models of colorectal and intestinal cancer]], [[mouse models of Down syndrome]] and [[mouse models of breast cancer metastasis]].

Reasons for common selection of mice are that they are small and inexpensive, have a widely varied diet, are easily maintained, and can reproduce quickly. Several [[generation]]s of mice can be observed in a relatively short time. Mice are generally very docile if raised from birth and given sufficient human contact. However, certain strains have been known to be quite temperamental.