If a mutation in the dna of an organism results in the replacement of an amino acid containing a polar r-group with another amino acid containing a nonpoler group, how might the structure of the protien be affected

The structure of the protein would be affected. Polar amino acids are hydrophilic and so they tend to be on the outside of the protein so they can be next to water. If the mutation changed a polar amino acid by a nonpolar then the new amino acid will tend to be on the inside of the protein, probably leading to a whole new conformity.