Homology arm: a region of a targeting constructplugin-autotooltip__default plugin-autotooltip_bigTargeting construct: a piece of DNA engineered in vitro that is used to make a knockout allele. used to make knockoutplugin-autotooltip__default plugin-autotooltip_bigKnockout: a knockout allele is a null allele generated through reverse genetics. allelesplugin-autotooltip__default plugin-autotooltip_bigAllele: a version of a gene. Alleles of a gene are different if they have differences in their DNA sequence. that matches the DNAplugin-autotooltip__default plugin-autotooltip_bigDNA: deoxyribonucleic acid. The genetic material for nearly all life on Earth. sequenceplugin-autotooltip__default plugin-autotooltip_bigSequence: the precise order of monomers in a polymer. In DNA, it refers to the order of G, A, T, and C nucleotides. In RNA, it refers to the order of G, A, U, and C nucleotides. In proteins, it refers to the order of amino acids. of the endogenous locusplugin-autotooltip__default plugin-autotooltip_bigLocus (plural form: loci): a physical location of a gene; often used as a synonym for a gene..