The genus of rats including R. norvegicus, the brown rat, and R. rattus, the black rat. The white laboratory rat is an albino form of R. norvegicus. The laboratory rat has 21 chromosome pairs including the sex chromosomes X and Y. The genome size is 2.75 gbp, and the estimated number of structural genes is 25,000. See Classification, Mammalia, Rodentia;.
Subjects: Genetics and Genomics.