Mutations 12-4

Mutations Mutation: a change in DNA sequence that affects the genetic information. Gene mutations: changes in a single gene-causes point or frame shift mutations Chromosomal mutations: changes in part or a whole chromosome

Gene Mutations Point mutations: affect only one nucleotide CATCATCAT 1. Substitutions CATCATCAT CATCTTCAT Ex.-Sickle cell anemia

Gene Mutations Frame shift mutations: change in one nucleotide affects all following nucleotides 2. Insertion CATTAGCAT CATTAGGCAT 3. Deletion Ex.- CF CATTGCAT

Chromosomal Mutations Change in the number or structure of chromosomes. 1. Deletion: loss of all or part of a chromosome Ex.-Cri-du-chat & Turner’s syndrome 2. Duplication: segment of chromosome is repeated 3. Inversion: segments are reversed

Chromosomal Mutations 4. Translocation: part breaks off and attaches to a non-homologous chromosome 5. Insertion: gain part of or a whole extra chromosome. Ex.-Down syndrome Look at examples on p. 346!

Cause and Effect Some inversions cause miscarriages. Several types of cancer are caused by translocations (leukemia). Mutagens are substances that cause mutations. Ex- X rays, certain chemicals, radiation