Science How could a zygote end up with an extra chromosome? Asked by arwen46 13 years ago 1/24/2013 7:05 AM Last updated by anonymous 13 years ago 1/25/2013 4:25 PM
A really critical phase for cell reproduction is the anaphase 1 and/or 2. If a nondisunction (failure of like chromosomes or chomratids to separate) happens, then you would end up with a zygote ending up with an extra chromosome.