How Could One Change In A DNA Nucleotide Alter The Formation Of The Translated Protein

How could one change in a DNA nucleotide alter the formation of the translated protein?

An example would be the difference between normal and sickle-cell hemoglobin.

Expert Answers
lynn30k eNotes educator| Certified Educator

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.