Practice question

Gene interaction typically involves non-allelic genes located at distinct loci, possibly on different chromosomes or distant same chromosome, encoding products functioning in common developmental or metabolic pathway. Interaction between alleles at same locus pertains to dominance relationships such as complete dominance, incomplete dominance, codominance, not gene interaction. Non-allelic interaction may occur with unlinked genes assorting independently yet produce masking, complementation, or additive effects altering dihybrid ratio. Distinguishing allelic from non-allelic interaction crucial for complementation tests, mapping, biochemical pathway ordering, as non-allelic loci recombine and complement in heterozygote.