Section 13.3 The sequence of bases in DNA are like the letters of a coded message. What would happen if one or a few of those letters changed accidentally, altering the message? What effects would you predict such changes would have on genes and the polypeptides for which they code? A permanent change of the nucleotide sequence of the DNAof an organism. - Chromosomal mutations - Point mutations A mutation involving a long segment of DNA. These mutations can involve deletions insertions Inversions translocations In some cases, the deleted sections may attach to another chromosome, disrupting both the one that loses the DNA and the one that gains it. A mutation involving a single nucleotide base substitution insertion Deletion Substitutions can affect one amino acid. - may have no affect .It all depends on what is substituted Examples: CCC CCACCC ACC proline prolineproline threonine Insertions / Deletions These are referred to as frameshift mutations because everything downstream of the mutation in affected. a. Insertions b. Deletions THE CAT ATE THE DOG THE CAT TAT ETH EDO G (Insertion of extra T) THE CAA TET HED OG (Deletion of T) Mutations may be artificially or naturally induced by Mutagens, including Pesticides Tobacco smoke Environmental pollutants Radiation Outcome may be Good Bad Neutral Click Smog for video