 Mutation – any change in DNA sequence  Can be caused by errors inside the cell ◦ Errors in  Replication  Transcription  Cell division (mitosis, meiosis)

 Outside Cuases of mutations = mutagens ◦ Radiation (x-rays, UV, nuclear, etc.) ◦ Chemicals (asbestos, formaldehyde, dioxins) ◦ High temperatures  Repair mechanisms – ◦ Proofreading enzymes try to replace incorrect nucleotides earthobservatory.nasa.gov/.../dna_mutation.gif

 Depends on the type of cell… ◦ Mutations in Reproductive Cells (sperm or egg) will be passed to offspring. ◦ Mutations in all other cells will only be passed to future cells but NOT offspring.  Can cause problems for individuals

THE DOG BIT THE CAT THE DOG BIT THE CAR (Point Mutation) THE DOB ITT HEC AR (Frameshift Mutation)

 Types of Mutations – 1. Point Mutations: change in single base pair May cause change in one amino acid.

2. Frameshift Mutations: shifts the reading of the mRNA codons a.) Addition of a base b.) Deletion of a base Deletion of an Adenine Generally are more harmful than point mutation.

3. Chromosomal mutations: changes in chromosomes.  Occurs during mitosis or meiosis  Broken, joined to wrong C, deletion, duplication, inversion  Can cause the biggest problems.  Delection C #5 : Cri du chat -- R. T: some Down Syndrome