Genetics

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Genetics in the news.
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Mutations

• are heritable changes in base sequences that
  modify the information content of DNA.

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Wild-type Allelestwo definitions

• General any allele existing at a frequency
  greater than 1 in a natural population,
• Experimental Geneticist the one allele that
  dictates the most commonly found phenotype in a
  population.

• Forward mutation any change that changes a
  wild-type allele to a different allele

A --gt a recessive mutation
b --gt B dominant mutation
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Mutant Classificationsby their effect on DNA

• Substitutions

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Mutagenic Agents
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To Know
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Mutant Classificationsby their effect on DNA
1 base? 2 base? 3 base? etc.

• deletions and insertions

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Frameshifts
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Mutant Classificationsby their effect on DNA

• inversions

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Trinucleotide Repeat Expansions
FMR1
Fragile X Mental Retardation 1
...GCGCGGCGGTGACGGAGGCGCCGCTGCCAGGGGGCGTGCGGCAGCG.
..
cgg
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gt 230
...
CTGGGCCTCGAAGCGCCCGCAGCCA
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Ames Testtesting for mutagenicity
More mutagenic? Barbecue beef Iceberg
Lettuce Cold Beer
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? AAUAAA
enhancer, silencer, core promoter?
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Transposable Elements

• a segment of DNA that can move to, or move a
  copy of itself to another locus on the same or a
  different chromosome (hopping DNA),
• may be a single insertion sequence, or a more
  complex structure (transposon) consisting of two
  insertion sequences and one or more intervening
  genes.

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Transposable Elements
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Transposition
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Transposons
Two transposable elements flanking other DNA, the
whole complex hops.
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? AAUAAA
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Assignments

• Chapter 7 Problems 7.1 - 7.12,
• Monday Prokaryotic Genetics, 8.1 - 8.3s