Question

You are working in a regional Blood Bank that performs paternity testing. The following request comes to you. These children have been typed for MNSs. The results are as follows:

Child 1 - Ns;

child 2 - MNSs;

child 3 - MS;

child 4 - MNs.

The mother's phenotype is MNs and the alleged father's phenotype is NSs. Is is possible that one of the children may not belong to the father? why/why not?

I want to make a punnett square here.. but I am confused on where to start.

Answer 1

Third children may not belong to father which have blood group MS. MS blood group only possible when the father also inherited M allele to the child. The M and N allele show codominant expression, both allele expresses itself when present together, so MS phenotype is not possible.
The genotype of the mother = MN 33 The genotype of the father = NNSs * Monohybrid cross for MN blood type. MN * NN Mother/ M M N ganfaller NMN INN MN ON NN (or N.) The blood NI MN INNI up can be either group can be eith * en Mono hybrid cross for the s&s allele mother = ss father Ss. Mother will produce only os gametes whereas trather will produce two types gametes S ands SS.S possible s ss ss So the possible genoptypes Ss and ss, and phenotypes are Ss and s * The possible phenotypes of the childs MNS; combine MN phenotype with Ss of ss NS, A Combine Nphenotype with Ss & ss MNS Ng

Second method is Mother's phenotype = M Ns gametes produced by mother = Ms and Ns father's phenotype = NSs gametes produced by father = NS and Ns Mother gametes/ m Ng father's gametes. LMs NS MNS, NNSS Ns MNss /NNss. Possible fonendrypes of the child a MNSs NSs MNS Ns
​​​​​