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Mutations

Mutations. Mutation. A change in the genetic material of an organism. Are mutations all bad?. Nope!. Mutation. Mutations are generally neutral or harmful to an organism In rare cases, mutations may be beneficial and provide an adaptive advantage over time. Mutations.

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Mutations

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  1. Mutations

  2. Mutation • A change in the genetic material of an organism Are mutations all bad? • Nope!

  3. Mutation • Mutations are generally neutral or harmful to an organism • In rare cases, mutations may be beneficial and provide an adaptive advantage over time

  4. Mutations... Can be put into two categories: • Single-gene Mutations • Chromosomal Mutations

  5. Single-gene Mutations Point Mutations • a mutation involving a change in a single base pair within a DNA sequence

  6. Point mutations • May arise from a • substitution of one base pair for another • Deletion or insertion of one or more base pairs from the DNA sequence

  7. Types of Point Mutations • Silent mutations • No effect on aa sequence in a protein Pg 263

  8. Types of Point Mutations • Missense mutations • An altered codon causes a different aa to be placed in the pr- Pg 263

  9. Types of Point Mutations • Nonsense mutations • Shortens a protein by introducing a stop codon instead of a specific aa Pg 263

  10. Types of Point Mutations Pg 262 • Frameshift mutations • Changes the reading frame if one or two nucleotides are affected

  11. Chromosomal Mutations • Involve changes in chromosomes • May involve many genes Types of Chromosomal Mutations • Deletion • Duplication • Inversion • Reciprocal translocation

  12. Deletion • A section of a chromosome is lost Pg 263

  13. Duplication • A section of a chromosome is copied one or more times Pg 263

  14. Inversion • (reverse orientation) • A chromosome is broken and re-inserted in the opposite direction Pg 263

  15. Translocation • A section of one chromosome breaking and fusing to another chromosome Pg 263

  16. Causes of Mutations Mutations can be... • Spontaneous • Induced

  17. Causes of Mutations Spontaneous Mutations • Take place naturally in a cell as a result of normal molecular interactions • Can occur during DNA replication and because of DNA transposition

  18. Transposons • aka. jumping genes • A segment of DNA that can move within the genome of an organism

  19. Causes of Mutations Induced Mutations • Caused by agents outside the cell • Eg. Exposure to mutagens

  20. Causes of Mutations Types of Mutagens • Physical Mutagens – those that physically change the structure of DNA • Eg. X rays, UV rays

  21. Causes of Mutations Types of Mutagens • Chemical Mutagens - a molecule that can enter the nucleus and induce mutations by reacting chemically with DNA • May cause a substitution or frameshift mutation

  22. Causes of Mutations Types of Mutagens • Chemical Mutagens • Eg. Nitrites, gasoline fumes, chemicals in cigarette smoke

  23. DNA Repair Cell have many mechanisms to repair DNA (aside from those discussed during DNA replication) All mechanisms involve a specific set of proteins that act by recognizing and then repairing the damage.

  24. Specific Repair • Mechanisms that fix certain types of damage • Eg. Photorepair Pg 265

  25. Non Specific Repair • Can correct different forms of damage • Eg. Excision repair Pg 265

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