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13.3 Mutations

13.3 Mutations. Mutation - a heritable change in genetic information. TYPES: 1) GENE - smaller 2) CHROMOSOMAL - larger. CHROMOSOMAL MUTATIONS. EX) Down’s Syndrome - extra 21 st chromosome . TYPES OF GENE MUTATIONS 1) Point Mutation - occur at single point on DNA strand.

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13.3 Mutations

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  1. 13.3 Mutations

  2. Mutation - a heritable change in genetic information

  3. TYPES: 1) GENE - smaller 2) CHROMOSOMAL - larger

  4. CHROMOSOMAL MUTATIONS

  5. EX) Down’s Syndrome - extra 21st chromosome

  6. TYPES OF GENE MUTATIONS • 1) Point Mutation - occur at single point on DNA strand

  7. Point Mutation #1 - Substitution - one base is changed to a different base

  8. #2 and #3) Insertion and Deletion - called “frameshift” mutations because they shift the codon frames.

  9. Frameshift mutations can alter the order of amino acids, therefore making the protein produced unable to perform its original function • frameshift mutations

  10. How Mutations Arise • Spontaneous Errors during replication • Mutagens - chemical or physical agents that cause mutations

  11. 1) Chemical mutagen from outside source

  12. 2) Free radicals - incomplete molecule parts that want electrons

  13. 3) High frequency light or radiation can mutate DNA

  14. BENEFICIAL MUTATIONS? • A mutation may alter protein production in a way that enables the organism to have a better survival rate in a changing environment • (how did we get here?)

  15. Hard to see beneficial mutations in humans when we do not have recent “selective pressure” killing us off in droves before we have a chance to reproduce • Possible examples: • 1) LACTOSE TOLERANCE • 2) HIV RESISTANCE

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