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Forensic Science - At a particular autosomal STR locus a man has alleles 5 and 8 and his wife has alleles 7and 4. What are all possible allele combinations for their offspring?

A) At a particular autosomal STR locus a man has alleles 5 and 8 and his wife has alleles 7and 4. What are all possible allele combinations for their offspring?

B) One of their children is typed for this loci and has alleles 7 and 7. Can these two individuals be the parents? Why or why not?

C) Another of their children is typed for this loci and has alleles 3 and 4. Can this child be their biological offspring? Why or why not?
Based on what you know about human population variation, do you think the current standards for calculating match probabilities is valid for courtroom evidence? Why or why not?

Solution Preview

A) At a particular autosomal STR locus a man has alleles 5 and 8 and his wife has alleles 7and 4. What are all possible allele combinations for their offspring?

Response: All we do is mix and match the various allele combinations just like we'd do in a typical monohybrid cross in Genetics class.

Man = STR-5/STR-8
Wife = STR-7/STR-4

Therefore, here's a Punnett Square:

STR-5 STR-8
STR-7 STR-5/7 STR-7/8
STR-4 STR-4/5 STR-4/8

Therefore, we see that all the possible allele combinations for their offspring are STR-5/7, STR-7/8, STR-4/5 and STR-4/8.

B) One of their children is typed for this loci and has alleles 7 and 7. Can these two individuals be the parents? Why or why not?

It doesn't look like any child can have STR-7/7, two copies of the 7-repeat allele. Obviously, ...

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