1. 6b: Chromosome Mutations 2. Chromosome MutationsMutations can occur at the gene by addingdeleting or substituting one or more letters fromthe genetic codeMutations can also occur on a larger scale at thechromosome which can affect thousands ofgenesChromosome mutations can involve a change inchromosome structure or numberChromosome mutations usually occur duringmeiosis 3. Structural Chromosome Mutations These mutations occur when pieces of thechromosome are broken off or extra pieces areadded Usually occur during the process of crossingover in meiosis 4. Portion of thechromosome is lostPortion of a homologouschromosome is gainedSegment of chromosomeis reversedSegment of non-homologouschromosome is addedDeletion disorder: Cri du chat syndrome 5. Chromosome Number MutationsChromosomes do not split correctly duringmeiosis NondisjunctionResulting gametes (egg/sperm) have more orless that the normal (n = haploid) number ofchromosomes 6. Normal Meiosis 7. Nondisjunction Meiosis 8. Genetic DisordersGeneticists can prepare a profile of a personschromosomes called a karyotypeUnderstanding which chromosomes have beenaffected by mutation allows doctors to diagnoseand treat genetic disorders 9. Karyotyping 10. Diagnose this patient... 11. Diagnose this patient...Male with extra 21st chromosome = Trisomy 21: Down Syndrome 12. Diagnose this patient... 13. Diagnose this patient...Male with an extra X chromosome = Kleinfelter's Syndrome 14. Diagnose this patient... 15. Diagnose this patient...Female with only one X chromosome = Turner Syndrome 16. Diagnose this patient... 17. Diagnose this patient...Female with extra X chromosome = Triple X Syndrome