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Mutations

Mutations. How will a change in the DNA sequence affect the overall properties of the protein?. Where mutations occur?. Somatic (body) cells: mutations are NOT passes to offspring. Gametes (sex) cells: mutations CAN BE passes to offspring through fertilization. Two types of mutations.

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Mutations

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  1. Mutations How will a change in the DNA sequence affect the overall properties of the protein?

  2. Where mutations occur? • Somatic (body) cells: mutations are NOT passes to offspring. • Gametes (sex) cells: mutations CAN BE passes to offspring through fertilization.

  3. Two types of mutations • Gene mutations: change in single nucleotides 2. Chromosomal mutations: occur when a section of chromosome relocate.

  4. Gene Mutations • PointMutations: occur when a single nucleotide is substituted for another nucleotide. Ex: THE DOG BIT THE CAT THE DOG BIT THE CAR

  5. Gene Mutations • Frameshift Mutations: occur when a single base pair is added (inserted) or subtracted (deleted) to “shift” the original nucleotides. Ex: THE DOG BIT THE CAT THE DOB ITT HEC AT (deleting the G, “shifted” the nucleotide to the left one place, thus coding for new amino acids)

  6. Results of gene mutations The mutation can be: a. Silent: codes for same amino acid b. Mis-sense: codes for another amino acid, changing the protein c. Nonsense: codes for a stop codon in an inappropriate place.

  7. Chromosomal Mutations • Deletions: a segment of nucleotides are removed. ABCDEFG ABFG 2. Inversions: detach and reattachment in reversing order of a segment of nucleotides: ABCDEFG ABEDCFG

  8. Chromosomal Mutations • Translocations: a segment of one chromosome detaches and reattaches to another chromosome. Ex. ABCDEF GHIJKL ABC DEFGHIJKL • Non-disjunction: unequal separation of chromosomes during meiosis. Ex. Trisomy: extra 21st X chromosome causing Down’s Syndrome. Ex. Monosomy: Turner’s Syndrome (sex chromosome) and Cri du Chat (chromosome 5)

  9. What causes mutations? • Mutagens: any agent that causes a change in DNA • High energy radiation: X-ray, Cosmic Rays, UV rays, and nuclear radiation • Chemicals: Dioxins, asbestos, Benzene, Cyanide and formaldehyde • High Temperatures • Science is the coolest!! We’re almost done!

  10. DNA Repair • Cells naturally identify and repair damage. However, too much damage may be irreparable. • Depends on: cell type, age of cell, and the extra cellular environment. • A cell that has accumulated a large amount of DNA damage, or one that no longer effectively repairs damage incurred to its DNA, can enter one of three possible states: 1. Permanent dormancy (senescence) 2. cell suicide (apoptosis) 3. unregulated cell division (cancerous)

  11. Are mutations good or bad? • Good? • New traits • Bad? • Mutation causing a new protein • Using the information you just learned explain how a mutation could occur that wouldn’t cause negative effect for a human.

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