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Understanding Mutations and Their Effects on Genetic Variation and Diseases

This article explains the different types of mutations, their impact on genetic variation and diseases, and the role of mutagens. It also discusses specific examples of mutations, including chromosomal mutations, gene mutations, and their effects on protein synthesis.

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Understanding Mutations and Their Effects on Genetic Variation and Diseases

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  1. Mutations -A mutation is a change in DNA sequence (order of nucleotides). -Mutations are important because they increase genetic variation (not all mutations are bad!)

  2. Mutations in Body Cells -Mutations in body (somatic) cells cannot be passed on to your children, however, they can cause cancer or other problems in your body. A cancer cell.

  3. Cancer as a result of mutations in somatic (body) cells: A person with skin cancer-This is why it’s important to always wear sunscreen!

  4. Cancer as a result of mutations in somatic cells: Tongue cancer and lung cancer are often caused by changes in body cells as a result of smoking, so don’t smoke!!!

  5. Mutations in Reproductive (Sex) Cells -Mutations in sex cells (sperm and egg cells) can lead to changes in the DNA sequence which will can be passed down to a person’s children.

  6. Good vs. Bad Mutations Mutations can be good as well as bad. A good mutation could lead to a change in a protein that allows an animal to run faster or see better. A bad mutation could lead to a change in a protein that causes a genetic disease such as Sickle Cell Anemia or Hemophilia.

  7. Mutagens • A mutagen is something that causes a mutation. Ex: radiation, chemicals, etc.

  8. Chernobyl- result of dangerous radiation released from nuclear core meltdown (1986)

  9. Chromosomal Mutations • May Involve: • Changing the structure of a chromosome • The loss or gain of part of a chromosome

  10. Chromosome Mutations • Five types exist: • Deletion • Inversion • Translocation • Nondisjunction • Duplication

  11. Deletion • Due to breakage • A piece of a chromosome is lost

  12. Inversion • Chromosome segment breaks off • Segment flips around backwards • Segment reattaches

  13. Duplication • Occurs when a gene sequence is repeated

  14. Translocation • Involves two chromosomes that aren’t homologous • Parts of the chromosomes are transferred to a DIFFERENT chromosome

  15. Translocation

  16. Gene Mutations: • There are 2 main types of these mutations: Point Mutations (Substitution) and Frameshift Mutations

  17. 1. Point mutation- Substitution -Point mutation-a change in one base pair in a DNA sequence. -A point mutation can cause an amino acid to change, which will change the structure of the protein being made. Example: AUG=Met AAG=Lys -Only one letter was changed/substituted (the A to a U) and the entire amino acid changed (from methionine to lysine).

  18. Picture of A Point Mutation mRNA Normal Protein Stop Replace G with A Point mutation mRNA Protein Stop

  19. Point mutations in our lives -Sickle cell anemia is a blood disease caused by a point mutation. -A single nucleotide is changed from “A” to “T” which causes the amino acid to change from glutamic acid to valine: Amino acids: Thr – Pro – Glu – Glu Normal: ACT CCT GAG GAG Sickle cell: ACT CCT GTG GAG Amino acids: Thr – Pro – Val – Glu

  20. Point mutations in our lives -People with sickle cell anemia often experience a lot of pain and swelling and have trouble exercising. Sickle cells do not move smoothly through blood vessels like normal cells do. Sickle cells get stuck and cause blood clots. Sickle cells also can’t carry Oxygen as effectively as normal Cells.

  21. Protein Synthesis and Mutation • Point mutation (base substitutions) • Missense mutation (one ‘wrong’ aa is coded) • Nonsense mutation (premature stop code) • Silent mutation (same aa is coded, so no effect)

  22. 2. Frameshift mutation -Frameshift mutation-adding or deleting nucleotides to a DNA sequence. -A frameshift mutation is usually much worse than a point mutation because it causes the entire DNA sequence to be shifted over! Example: DNA: ATTAAACCG ATAAACCG Delete this T

  23. Frameshift (insertions and deletions) Deletion of U mRNA Frameshift mutation Protein

  24. Protein Synthesis and Mutation • Insertions/deletions • Frameshift mutation • Dramatic change in amino acids. All codons affected after the mutation • Run-ons, premature stops (nonsense mutation)

  25. Frameshift Mutations • Crohn’s Disease is caused by a frameshift mutation. • It causes inflammation to the digestive tract.

  26. More Mutations

  27. Questions: Is this a point (substitution) mutation or a frameshift mutation?

  28. Questions: THE CAT ATE THE RAT THE CAR ATE THE RAT Substitution (point) or frameshift?

  29. Questions THE DOG BIT THE CAT THE DOB ITT HEC AT Point (substitution) or frameshift? *COMPLETE THE MUTATION SHEET(S) IN CLASS

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