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Mutations

Mutations. Exploring the source and exploitation of genetic alterations. Is there evidence that DNA itself can be altered?. General Information. Explanation: A mutation is a permanent change in the structure or amount of genetic material of an organism Causes:

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Mutations

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  1. Mutations Exploring the source and exploitation of genetic alterations

  2. Is there evidence that DNA itself can be altered?

  3. General Information Explanation: A mutation is a permanent change in the structure or amount of genetic material of an organism Causes: Can occur naturally as a mistake (sometimes DNA polymerase does not catch all mistakes) Mutagens in environment (radiation or chemicals) Effects: May harm, help, or have no effect

  4. How Can Mutations Occur? They can be inherited from a parent (hereditary mutation) Mutation present in egg or sperm cell As the zygote divides, mutation is copied into the DNA of almost every cell in the body. Is present throughout a person’s lifetime.

  5. How Can Mutations Occur? They can be acquired over a person’s lifetime (somatic mutation) De Novo (new) Mutation occurs just after fertilization. Person has mutation in every cell, but they did not inherit it from parent. Somatic: Mutation occurs in DNA of certain cells during a person’s life. May be caused by environmental factors such as UV radiation (skin cancer). Cannot be passed to next generation

  6. What types of mutations are there?

  7. Types of Mutations Gene mutations Small-scale change in single base nucleotide Chromosomal mutations Large-scale change in the number or structure of chromosomes

  8. Substitution AGCTCCT AGCTCAT • A single nucleotide is replaced withanother • May result in an different amino acid during translation • May render the protein ineffective or may be neutral

  9. Insertion AGCTCCT AGCATCCT • A single nucleotide is addedto the original sequence • Results in several different amino acids • Usually renders the protein ineffective

  10. Deletion AGCTCCT AGCTCT • A single nucleotide is removed from the original sequence • Results in several different amino acids • Usually renders the protein ineffective

  11. Gene Mutations can be • Point mutations that may alter a single amino acid or • Frameshift mutations that shift the “reading frame” of the DNA & alters more than one amino acid (remember DNA bases are read in 3’s; codons)

  12. Point MutationSubstitution AGCTCCT AGCTCAT Normal: • THE BIG FAT CAT ATE THE RAT Substitution: • THE BIZ FAT CAT ATE THE RAT

  13. Frameshift MutationInsertion AGCTCCT AGCATCCT Normal: • THE BIG FAT CAT ATE THE RAT Insertion: • THE BIG ZFA TCA TAT ETH ERA

  14. Frameshift MutationDeletion AGCTCCT AGCTCT Normal: • THE BIG FAT CAT ATE THE RAT Deletion: • THE IGF ATC ATA TET HER AT

  15. Chromosomal mutations… Large-scale change in the number or structure of chromosomes

  16. Types of chromosomal mutations: • Deletion of all or part of a chromosome • Duplication repeats a segment of a chromosome • Inversion is when part of a chromosome becomes oriented in the reverse of its usual direction • Translocation is when part of one chromosome breaks off and attaches to another, non-homologous chromosome

  17. Deletion

  18. Duplication Normal: • THE BIG FAT CAT ATE THE RAT Duplication: • THE BIG FAT FAT CAT ATE … Sometimes tandom repeats: • THE BIG FAT FATFAT CAT… • THE BIG FAT FATFATFAT CAT… That's a fat cat 

  19. Duplication

  20. Inversion

  21. Translocation

  22. How do Mutations effect certain Traits? Remember: Traits are expressed by proteins Proteins are chains of amino acids Amino acids are determined by codons on mRNA mRNA is transcribed from DNA

  23. How do Mutations effect certain Traits? • If there is a mutation on the strand of DNA • mRNA will be transcribed incorrectly • The wrong amino acid will be linked to the chain • The resulting protein, if any, will be useless • The trait will not be expressed properly

  24. Are mutations good or bad? • Increase diversity among populations and sometime enabling some individuals to survive better • These “good” genes are then passed on to future generations • Can cause and pass on genetic disorders

  25. Ex: Sickle Cell Anemia A genetic disorder in which abnormal amounts of the protein hemoglobin causes red blood cells to have a sickle shape. • This causes the red blood cells to clot, which leads to a lot of pain.

  26. Chromosome Mutations Down Syndrome Chromosome 21 does not separate correctly 47 chromosomes instead of 46 Trisomy 21 May develop slower, may have heart and stomach issues

  27. Chromosome Mutations Cri-du-chat Deletion of material on chromosome 5 Characterized by the cat-like cry made by cri-du-chat babies

  28. Sex Chromosome Mutations Klinefelter’s Syndrome XXY, XXYY, XXXY Male Sterility May have female characteristics

  29. XYY Syndrome Normal male traits Often tall and thin Associated with antisocial and behavioral problems Sex Chromosome Mutations

  30. Sex Chromosome Mutations Turner’s Syndrome X Female Sex organs do not mature at adolescence Sterility Short stature

  31. Sex Chromosome Mutations XXX Trisomy X Female Little or no visible differences Tall stature Learning disabilities Limited fertility

  32. TOTD • What are the two main groups of mutations? • How does a point mutation compare with a frameshift mutation? • Which type of mutations have a greater impact: gene or chromosomal, point or frameshift? • Give an example of how a mutation may be advantageous. Give an example of a “bad” mutation.

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