Mutations

General Information Definition: Causes: Effects: A mutation is a change in the structure or amount of genetic material of an organism Causes: Can occur naturally as a mistake (sometimes DNA polymerase doesn’t catch all mistakes) Mutagens in environment (radiation, chemicals) Effects: May harm, help, or have no effect

How Can Mutations Occur? They can be inherited from a parent (hereditary mutation) Mutation present in egg or sperm cell As the zygote divides, mutation is copied into the DNA of almost every cell in the body. Is present throughout a person’s lifetime

How Can Mutations Occur? They can be acquired over a person’s lifetime (somatic mutation) De Novo (new): When mutation occurs just after fertilization. Person has mutation in every cell, but they didn’t inherit it from parent. Somatic: When mutation occurs in DNA of certain cells during a person’s life. Can be caused by environmental factors such as UV radiation (skin cancer). Cannot be passed to next generation

Kinds of Mutations THE – CAT – ATE – THE – RAT Point Mutation (substitution) A change of a single nucleotide in a sequence from one kind of base to another Normal DNA THE – CAT – ATE – THE – RAT Mutated DNA THE – BAT – ATE – THE – RAT

Kinds of Mutations THE – CAT – ATE – THE – RAT Frameshift Mutation (deletion/insertion) When a nucleotide is inserted or deleted, the sequence may be read as different codons Normal DNA THE – CAT – ATE – THE – RAT Mutated DNA THE – ATA – TET – HER – AT

How do Mutations effect certain Traits? Remember: Traits are expressed by proteins Proteins are chains of amino acids Amino acids are determined by codons on mRNA mRNA is transcribed from DNA IF there is a mutation on the strand of DNA mRNA will be transcribed incorrectly The wrong amino acid will be linked to the chain The resulting protein, if any, will be useless The trait won’t be expressed properly

Ex: Sickle Cell Anemia This causes the red blood cells to clot, which leads to a lot of pain A genetic disorder in which abnormal amounts of the protein hemoglobin causes red blood cells to have a sickle shape.