Chapter 13.3 (Pgs. 372-376): Mutations

Mutations Are heritable changes in genetic information Have two major types: Chromosomal mutations Point mutations Can be harmful or beneficial

Chromosomal Mutations Involve changes in the number or structure of chromosomes Deletion Loss of all or part of a chromosome Duplication Produces an extra copy of all or part of a chromosome Inversion Reverses the direction of parts of a chromosome Translocation Part of one chromosome breaks off and attaches to another chromosome

Point Mutations Are mutations that involve changes in one or more nucleotides Occur at a single point in the DNA sequence Can cause changes to occur further along the DNA molecule from the initial mutation

Point Mutations Substitution Sickle Cell Anemia One nucleotide is changed to a different nucleotide Sickle Cell Anemia

Point Mutations Insertion or Deletion Huntington’s Disease One nucleotide is inserted or removed from the DNA sequence Huntington’s Disease Muscular Dystrophy

Point Mutations Frameshift Mutations that change the “reading frame” of DNA Change the sequence of DNA from the initial point of mutation

Causes of Mutations Include naturally-occuring errors Can occur during replication Include chemical and physical agents in the environment, called mutagens Chemicals Radiation

Effects of Mutations Can be harmful Can be helpful Change protein structure or gene activity in a negative way Sickle cell anemia Can be helpful Change protein structure or gene activity in a positive way Increase disease resistance Create better physiological function Some mutations have no effect at all