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Genetic Mutations Unit 2-2 Notes Mr. Hefti – Pulaski Biology 1. Genetic Mutations “a change in the DNA of a gene” –Mutations in gametes can be passed on to offspring –Mutations in body cells affect only the individual in which they occur 2. Categories • Point Mutations – Change in one or just a few bases in a gene • Frameshift Mutations – Cause genes to be read in the wrong threenucleotide sequence Three nucleotide sequences are called “codons” New rule: when referring to the amino acids that DNA codes for, T still goes with A, but now A goes to U (which stands for Uracil). See if you can find the amino acid that these DNA sequences code for using the Universal Codon Chart… CAT GUA T T A = valine A AU = asparagine Read from the top second. Read from this side first! Then read from this side third. 2A. Point Mutations • Substitution – One nitrogenous base is replaced with a different one –C T A G G A –G A U C A U • GAU = ? / CAU = ? / CCU = ? –Aspartate / Histidine / Proline 2B. Frameshift Mutations • Insertion – One or more bases are added to a gene –T A G C C T –A G U C G G A • AGU = ? / AUC = ? / CGG = ? –Serine / Isoleucine / Arginine 2B. Frameshift Mutations • Deletion – One or more bases are deleted from a gene –C G A T A G – __C U A U C • GCU = ? / AUC = ? –Alanine / Isoleucine • CUA = ? / UC = ? –Leucine / “Nothing” 3. Sources of Mutations • X-rays • UV rays • Radiation • Asbestos • Alcohol • LSD • Marijuana • Benzene • Formaldehyde 4. Genetic Diseases • Some genetic diseases are caused by inherited mutations – Sickle cell anemia – Tay-Sach’s disease – Cystic fibrosis – Hemophilia – Huntington’s disease Sickle cell anemia • Recessive • Causes for the abnormal development of rbc’s • Sickle shape causes cells to break apart or get jammed in blood vessels Tay-Sach’s disease • Recessive • Causes infants’ nervous systems to break down – Death in early childhood Cystic Fibrosis • Recessive • Causes for the overproduction of mucus • Mucus clogs organs, especially lungs making breathing difficult Hemophilia • Sex-linked recessive • Blood clotting disorder Huntington’s disease • Dominant • Causes brain to gradually deteriorate • Usually goes unnoticed until adulthood