Final answer:
Results from a single locus can indeed prove someone is not the father of a child if the child possesses an allele at the locus that is not present in the man being tested. Technicians use similarities in sequences to establish paternity, and the exclusion of a father can be based on discrepancies at a single locus, although multiple markers are usually evaluated for accuracy. Mendel's theory of inheritance and autosomal dominant inheritance patterns also play a role in understanding how traits and disorders are passed down.
Step-by-step explanation:
Yes, results from a single locus can prove someone is not the father of a certain child. In paternity testing, if the child possesses an allele at a locus that is not present in the alleged father, it is a clear indication that the man cannot be the biological father, as the child must inherit one allele from the mother and one from the biological father. The child's DNA fingerprint must contain a combination of the mother's and father's alleles at each locus tested to establish a biological relationship to the parents.
Using similarities in sequences, technicians examine multiple loci to increase the accuracy of paternity testing. Discrepancies at even a single locus can exclude paternity, but a conclusive determination often requires multiple genetic markers to be evaluated. The analysis of DNA from a potential father and a child is based on the inheritance patterns of specific alleles that are passed from parents to offspring.
Additionally, Mendel's theory of inheritance and the concept of autosomal dominant inheritance explain how genetic traits are passed on and can predict the appearance of single-gene disorders such as cystic fibrosis based on parental genotypes. However, the expression of genetic disorders can also be influenced by chance, illustrating the complexity of genetic inheritance beyond a single genetic locus.