Mutations

Spontaneous mutations are mistakes made by DNA Polymerase 3 or 1.

Induced mutations are caused by mutagens like UV lights, X-rays, chemicals and some viruses.

Point mutations

• Changes to a single base pairing

• Silent mutations have no effect

• Missense mutations do alter amino acid sequence.

  • Sickle cell anemia, change in one amino acid causes red blood cells to change shape from round to “sickle” limiting the surface area required to carry oxygen to the cells of the body

  • Limone disorder

• Nonsense mutations have a premature stop codon that prevent the protein from being translated

  • Albinism (no longer produces melanin)

Frameshift mutation

• Change in reading frame

• Deletion mutations

  • B Thalassemia (Lack of hemoglobin produced)

  • Cystic fibrosis - entire codon is deleted leading to lack of protein required to clear lungs of mucus

• Insertion mutations

  • Tay-Sachs Disorder (Deterioration of nerve cells caused by an insertion of 4 bp)