You will need to put your model chromosomes back together for the next part of this activity. the diagram shows how your partner has put them together. you realize that this arrangement of the model chromosomes could never occur in a real cell. what is wrong? explain why sister chromatids could not have different alleles.

Sister chromatids have different alleles although carry same genes on same loci. So if it doesn't happen so, like if there are same alleles on sister chromatids then there is a problem in its formation. i.e., male and female alleles haven't contributed equally ( may be an error during their segregation process ). And obviously it doesn't happen in a real cell so we must understand this point. Because normally whenever it happens there's one half from the male and one half  from the female. (i.e. maternal and paternal alleles contribute equally).

I hope you get the answer!!!

condensation. good luck!