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 very regularly Almost all mutations are neutral Many mutations are repaired by enzymes

4. Are Mutations Helpful or Harmful? Some type of skin cancers and leukemia result from somatic mutations Every once in a long while, mutations may improve an organism’s survival (beneficial) (lactose tolerance)

5. Types of Mutations - Chromosomal Mutations - Gene Mutations

6. Chromosome Mutations –Changing the structure of an entire 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. Nondisjunction Failure of chromosomes to separate during meiosis Causes gamete to have too many or too few chromosomes

14. Chromosome Mutation Animation

16. 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.

17. Types of Gene Mutations Include: –Point Mutations Substitutions, Insertions, Deletions –Frameshift mutations Insertions and deletions

18. Point Mutation Change of a single nucleotide Includes the insertion, deletion, or substitution of ONE nucleotide in a gene

19. Gene Mutations Point mutations – a mutation that occurs at a single point (only 1 nucleotide is changed) –Substitution – a single nucleotide is substituted for another one (A instead of G) –Insertion – a nucleotide is added –Deletion – a nucleotide is removed

20. Frameshift Mutation Inserting or deleting one or more nucleotides Changes the “reading frame” like changing a sentence Proteins built incorrectly

21. Gene Mutations Insertions and deletions cause frameshift mutations because they shift the “reading frame” of the genetic message.

22. Frameshift Mutation Original: –The fat cat ate the wee rat. Frame Shift Insertion (“a” added): – The fat caa tat eth ewe era t. Frame Shift deletion (“a” deleted): –The fat cta tet hew eer at.

23. Gene Mutation Animation

24. https://www.youtube.com/watch?v=GieZ 3pk9YVo https://www.youtube.com/watch?v=O_5 WfI9YCqk