1. Mutations and Genetic Disorders

2. Review

3. One Wrong Letter http://youtu.be/o3yQZp5Rs-o Questions to think about: 1) How is the little boy in the video different than other kids? 2) What causes Tay Sach’s Disease? 3) Can this be cured? Why or why not?

4. What is a Mutation?  Mutation : a change in an organism’s DNA  Can be genetically or environmentally caused  What part of the DNA molecule do you think could change, and cause an effect?  Most genetic disorders come from a mutation in one gene. DNA sequence (Nitrogen bases)

5. Results of a Mutation  A mutated gene produces a flawed protein  It may work some or not at all

6. 1) Point Mutations = substitution of a base in 1 gene 2) Deletion of an entire gene or genes 3) Chromosomal = an extra or missing chromosome Types of Genetic Disorders

7. Example: Sickle-Cell Disease  Red Blood Cells (RBC) carry oxygen to every part of the body  In Sickle-Cell Disease, the RBC are abnormally shaped – stretched out and skinny  Causes blockage of blood vessels

8. Example: Progeria  Causes accelerated aging

9. Example: Marfan Syndrome  Causes bones to overgrow and create loose joints

10. Other Causes of Mutations  Mutagens: chemical or physical agents (environmental factors) that can cause a mutation  Examples:  UV radiation  Pollution  Certain chemicals  Viruses

11. Warm-Up 1) Put these words in order: protein, genes, physical trait, DNA, 2) What is a mutation? 3) What is the result of a mutation?

12. Germ-Line vs. Somatic Cell Mutations

13. Gamete (Germ Line)Cell Mutations  Gamete – sex cells (egg or sperm)  Only mutations in gametes can be passed on to offspring  The mutation will occur in every cell (because of cell division)

14. Body (Somatic) Cell Mutations  Somatic Cell – body cell (bone, tissue, etc.)  Mutations in any body cell cannot be passed on to offspring  Occurs in one type of cell  Ex. Skin cancer from exposure to UV rays

16. Analyze the Diagram  Determine which diagram is a gamete cell mutation and which one is a body cell mutation. How do you know? Where did the mutation occur?

17. 60-Second Quick Write  Compare gamete cell mutations to body cell mutations. Write your response in your notes.

18. Substitution, Insertions, and Deletions

19. Gene Mutations Caused by Point Mutation Go to Section: 1.Point mutations : one base is replaced with the wrong base (letter) Also called Base-Pair Substitutions Example: Sickle-cell anemia, color blindness

20. 1.What is the original DNA strand? 2.What is the original transcribed RNA? 3.Where did the original mutation occur? 4.What affect did this mutation have on mRNA? 5.What amino acid is translated differently?

21. Point Mutations can be… 1.Silent 2.Missense 3.Nonsense

22. Point Mutations: Silent Gene Mutations 1.Silent mutation: a base is changed, but the new codon codes for the same amino acid. ( typically it is the third letter in the codon) Original mRNA Protein leading to a silent mutation

23. Point Mutations: Missense Mutations Go to Section: 1.Missense Mutations: point mutation that still codes for an amino acid, just the wrong amino acid 2.May or may not be harmful Original mRNA Protein

24. Nonsense mRNA Protein Point Mutations: Nonsense Mutations 1.Nonsense mutations: prematurely code for a stop codon 2.Result: a nonfunctional protein Original

25. Think, Pair, Share: 1.Which point mutation effect (silent, missense, nonsense) could be the least harmful? Why? 2.Which point mutation effect could be the most harmful? Why?

26. Deletion Gene Mutation caused by a Deletion Go to Section: 2. Deletion: one or more of the bases is deleted from the code Causes a shift in the reading frame Often causes missense of nonsense

27. Insertion Gene Mutations caused by an Insertion Go to Section: 3. Insertion: one or more base pairs are inserted into the code Causes a shift in the reading frame Often causes missense or nonsense

28. You Try : Decide if the mutation is a point mutation, insertion, or deletion. Original DNA Strand:AGTCGA Mutation Type: ___________ Mutation #1:AGGTCGA Original DNA Strand:AGTCGA Mutation Type: ____________ Mutation #2:ATCGA Original DNA Strand:AGTCGA Mutation Type: ____________ Mutation #3:AGACGA