How could one change in a DNA nucleotide alter the formation of the translated protein?An example would be the difference between normal and...

DNA codes for proteins by the sequence of nucleotides in the DNA. Each set of 3 nucleotides codes for a specific amino acid. Sometimes, a change in a nucleotide does NOT change the amino acid (and therefore, the protein) because some amino acids have more than one set of 3 nucleotides that code for them. Leucine, for example, is coded for by CTT, CTA, CTC, and CTG. A change in the last nucleotide wouldn't matter. But for others, it matters very much. CAC codes for histidine, and CAA for glucagon. Also, if a nucleotide is added or lost from a strand of DNA it alters the entire sequence, as the "frame" shifts; the "reading" of the DNA is off, and all the sets of 3 are altered.