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6 .2 Mutations

6 .2 Mutations. Pages 234-239. Mutations. can be caused by: - e nvironmental agents - errors during cell division. Radiation. Exposure to radioactive materials can cause genetic mutations. Chemicals.

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6 .2 Mutations

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  1. 6.2 Mutations Pages 234-239

  2. Mutations can be caused by: - environmental agents - errors during cell division

  3. Radiation Exposure to radioactive materials can cause genetic mutations.

  4. Chemicals • Examples: Nitrosonguanidine (NTG), Hydroxylamine, Bromodeoxyuridine (BrdU), and Ethidiumbromide

  5. Effects • Positive, negative or neutral effect on phenotype or cell death

  6. Point Mutations • A failure of the genetic machinery to copy the DNA perfectly.

  7. Base-pair substitution The wrong nitrogenous base pair is included.

  8. Insertion Extra nitrogenous bases are included during the copying of the DNA.

  9. Deletions • One or more base pairs are left out during the copying of DNA

  10. Chromosome mutations Involve the entire chromosome or major chunks Non-disjunction(sister chromatids fail to separate during meiosis) • Down syndrome • Turner syndrome • Patau syndrome

  11. Chromosome mutations • Large scale deletions, insertions, duplications or inversions (flipping) of entire portions of a chromosome

  12. Inheriting mutations • The genetic machinery is designed to find and fix copying errors. (less successful with age)

  13. Inheriting mutations • Most of the DNA does not code for genes (so errors here are meaningless)

  14. Inheriting mutations • Mutations in autosomes are not passed on to the next generation

  15. Inheriting mutations • Mutations in sex cells can be passed on to the next generation

  16. Dominant vs. Recessive • Mutations can be dominant and appear in the first generation. Ex. Huntington’s disease • Mutations can be recessive and appear only rarely when two individuals with the same mutation produce offspring. Ex. Cystic Fibrosis

  17. Sickle cell anemia • Misshapen red blood cells can cause pain and an increased risk of infection

  18. Sickle cell anemia • Malaria parasite enters red blood cell causing it to become sickle-shaped and leading to its destruction and removal.

  19. Lactose Tolerance • Most babies tolerate lactose producing the enzyme needed to digest their mother’s milk • 75% of adults do not tolerate lactose • 25% of adults have a mutation in their genes that allows them to digest lactose.

  20. Spontaneous mutations • Happen by accident

  21. Induced mutations • Result due to exposure to a physical or chemical agent

  22. Antibiotic Resistance • Usually antibiotics kill bacteria by weakening their cell wall. • Mutations in genes that code for the cell wall allow the bacteria to be resistant to antibiotics.

  23. Jumping Genes • Transposons are segments of the DNA that can move from place to place. • Transposition is the act of moving a segment of DNA from one place to another. • Example: Indian corn

  24. hemophilia • A transposon can insert itself into a gene for normal blood factor VIII, causing hemophilia in boys (X-linked gene).

  25. Microarray Technology Microarray -small membrane or glass slide -contains samples of hundreds or even thousands of DNA fragments -arranged in a regular pattern. -Each fragment corresponds to a gene

  26. Microarray

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