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Instability: Mutation and DNA repair

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Presentation on theme: "Instability: Mutation and DNA repair"— Presentation transcript:

1 Instability: Mutation and DNA repair
Substitution rates vary throughout the genome.

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3 Instability: Mutation and DNA repair
Types of substitutions Transitions/Transversions Transition bias A G C T

4 Instability: Mutation and DNA repair
Different mutation rates in primates and rodents Species Pair Sites Percent Divergence Substitution rate (x 109) Human/Chimp (7 myr) Human/Old world monkey (25 myr) Mouse/rat (15 myr)

5 Instability: Mutation and DNA repair
Higher mutation rates in males Greater number of cell divisions

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7 Instability: Mutation and DNA repair
Sex-specific differences in mutation rates Gene Mutation Ratio of male/female mutations NF1 Point 4.5 VHL Point 1.3 RB Point 8.5 ZFX/ZFY Mutations in last intron 6

8 Instability: Mutation and DNA repair
Mechanism of mutation Simple sequence repeats and strand slippage

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11 Instability: Mutation and DNA repair
Mechanism of mutation Homologous equal crossover yields fusion genes.

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13 Instability: Mutation and DNA repair
Mechanism of mutation Unequal crossover causes insertions and deletions.

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15 Instability: Mutation and DNA repair
Mechanism of mutation Unequal crossover in a tandem repeat array can result in sequence homogenization.

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17 Instability: Mutation and DNA repair
Mechanism of mutation Tandem gene duplication by unequal crossover or sister chromatid exchange facilitated by short interspersed elements.

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19 Instability: Mutation and DNA repair
Mechanism of mutation Gene conversion Non reciprocal sequence exchange between allelic or nonallelic genes.

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23 Instability: Mutation and DNA repair
Mechanism of mutation Splicing mutations Intron retention Exon skipping Activation of cryptic splice sites

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26 Instability: Mutation and DNA repair
Mechanism of mutation Short tandem repeats are deletion insertion hotspots.

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28 Instability: Mutation and DNA repair
Mechanism of mutation Spinocerebellar ataxia (SCA1) triplet repeat expansion.

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30 Instability: Mutation and DNA repair
Mobile elements and mutations Alu element Insertion events Recombination events

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32 What are SINEs? 1. Interspersed Elements 2. 70 - 300 Bases in Length
3. Very High Copy Numbers (>100,000 Copies/Genome)

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36 Instability: Mutation and DNA repair
Photodimer DNA glycosylase /AP endonucleases E-coli mismatch repair Human mismatch repair

37 Instability: Mutation and DNA repair
Photodimer

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39 Instability: Mutation and DNA repair
DNA glycosylase /AP endonucleases

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41 Instability: Mutation and DNA repair
E-coli mismatch repair Human mismatch repair

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44 Instability: Mutation and DNA repair
Human mismatch repair

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