Lec 7 u2013 Origin of Variation pt. 2 - LECTURE 7 Origin...

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LECTURE 7 – Origin of VariationMUTATION? SUPPOSE THAT DNA REPLICATION ERRORS RESULT IN A A:T BASE PAIR BEING REPLACED BY A G:C PAIR. Is this change a mutation?Yes, a double stranded change in the DNA sequence is a mutationConsequence of mutation is irrelevant Only 2% is coding for proteinMore than half of genome are mobile elements Repair mechanisms ensure DNA stays the same one generation to the nextHOW MUCH VARIATION IS THERE? GENOME PROJECT REPORTGenome in 2000 was composite genome: genomes from multiple people2504 genomes, 26 populations don’t need to know those numbers0.14% different from reference genomeoDifference between people is 1.4%1.4% different from chimpsVast majority of variants are SNPs (single nucleotide polymorphism)About 2500 structural variations including mobile elements, CNV (copy number variation diff # of copies of genes), inversions, etcoNot just bases, but entire structures12000 variants in coding regionso12,000 differences in a genome compared to others 100 variants are de novoo“de novo” newoMutations exist that aren’t present in either parentso100 mutations that aren’t inherited from parents 30 variants associated with diseaseBACTERIAL ELEMENTS CODE FOR THEIR OWN MOBILITY (TRANSCOPASE)Sequences of DNA that are mobile: code for their own mobilitySimplest sequences in bacteria (insertion sequences) and code for an enzyme called transposaseoEnables element to move from one place to another Sequences in genome that can move themselves = mutationsGenome is full of elements that know how to moveInsertion sequence is most commonoCodes for its own mobilityTransposes allows things to move from one location to another in bacterial genome2 insertion sequences can move DNA between themocalled a transposonoAssociated with drug resistance in bacteria

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