Mutations Powerpoint.ppt
- 1. Mutations
- 2. What Are Mutations? • Changes in the nucleotide sequence of DNA • May occur in somatic cells (aren’t passed to offspring) • May occur in gametes (eggs & sperm) and be passed to offspring
- 3. Are Mutations Helpful or Harmful? • Mutations happen regularly • Almost all mutations are neutral • Chemicals & UV radiation cause mutations • Many mutations are repaired by enzymes
- 4. Are Mutations Helpful or Harmful? • Some type of skin cancers and leukemia result from somatic mutations • Some mutations may improve an organism’s survival (beneficial)
- 6. Chromosome Mutations • May Involve: – Changing the structure of a chromosome – The loss or gain of part of a chromosome
- 7. Chromosome Mutations • Five types exist: – Deletion – Inversion – Translocation – Nondisjunction – Duplication
- 8. Deletion • Due to breakage • A piece of a chromosome is lost
- 9. Inversion • Chromosome segment breaks off • Segment flips around backwards • Segment reattaches
- 10. Duplication • Occurs when a gene sequence is repeated
- 11. Translocation • Involves two chromosomes that aren’t homologous • Part of one chromosome is transferred to another chromosomes
- 12. Translocation
- 13. Nondisjunction • Failure of chromosomes to separate during meiosis • Causes gamete to have too many or too few chromosomes • Disorders: – Down Syndrome – three 21st chromosomes – Turner Syndrome – single X chromosome – Klinefelter’s Syndrome – XXY chromosomes
- 17. Gene Mutations • Change in the nucleotide sequence of a gene • May only involve a single nucleotide • May be due to copying errors, chemicals, viruses, etc.
- 18. Types of Gene Mutations • Include: – Point Mutations – Substitutions – Insertions – Deletions – Frameshift
- 19. Point Mutation • Change of a single nucleotide • Includes the deletion, insertion, or substitution of ONE nucleotide in a gene
- 20. Point Mutation • Sickle Cell disease is the result of one nucleotide substitution • Occurs in the hemoglobin gene
- 21. Frameshift Mutation • Inserting or deleting one or more nucleotides • Changes the “reading frame” like changing a sentence • Proteins built incorrectly
- 22. Frameshift Mutation • Original: – The fat cat ate the wee rat. • Frame Shift (“a” added): – The fat caa tet hew eer at.
- 25. FYI
- 26. Normal Male 26 2n = 46
- 27. Normal Female 27 2n = 46
- 28. Male, Trisomy 21 (Down’s) 28 2n = 47
- 29. Female Down’s Syndrome 29 2n = 47
- 31. Turner’s Syndrome 31 2n = 45