After two rounds of replication there is a mutation

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After two rounds of replication there is amutationYou can see a change in double stranded DNAoThis is why it is a mutagenTautomeric shifts could add 5-bromouracil instead ofthymineoThymine and uracil are pretty similar (and theyare tautmerically stable)o5-bromouracil is pretty differentit enhances tautomeric instabilityMechanisms of substitution mutagenesis during DNA replicationMechanism of Indel Mutagenesis during replicationCopy Number VariationsoIn/del MutationInsertion/deletionOne or two base pairs missing or addedoIf there are many of the SAME base pairs in a row then one can slip outThis is REPLICATION SLIPPAGE (11:00-12:46)Slippage on new strand adds an extra base pairSlippage on the old strand deletes a baseThis is the smallest type of CNVMechanism of chromosomal rearrangements resulting from double strand breaksRepairing double-stranded breaks can create rearrangementsoWhen the DNA is “slammed back together” you might lose some of the genes or gain extra copies of the genesoIt will be imperfectRole of UV, ionizing radiation and ROS is mutagenesisUV light causes neighboring thymines to bond—dimeroHumans repair this by excision (mismatch)oBacteria fix by photolyaseThymine dimer is serious damageoVery difficult to replicateoThis will force a cell into apoptosis—forces cell deathX-rays and gamma rays go through our body (go through the water)oRip electrons away from the oxygen in wateroThis further causes oxygen to go after the electrons from proteinsResults in double stranded breaks in chromosomesoThis is ROSDAMAGES DNA (17:00~) (lecture 8)
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Cycle 4: Recombination and Meiosis9.1 and 9.3 Textbook (Figures: 9.1, 9.10, 9.11 and 9.13 !!)The basic mechanism of DNA recombination in MeiosisGenetic recombination requires:oTwo DNA molecules that are different from each otheroMechanism for bringing the molecules close to each otheroCollection of enzymes to cut, exchange and glue DNA back togetherHomology allows DNA to recombine preciselyoThe regions of DNA are pairedoEnzymes break a covalent bondoFree ends of the backbone are exchanged and then reattached to those of another DNA moleculeCUTTING AND PASTING FOUR DNA BACKBONES IN ONE RECOMBINATION EVENTThe stage of meiosis when recombination occursRecombination usually occurs in prophase ILecture 8SNP’s come from failure of proofreading and mismatch repairDNA polymerase cannot distinguish analoguesThymine is tautomeric-ly stableInversion nor Translocation count as CNVNormal Crossing-over does not result in CNVsoUnequal crossing over results in CNVsThe genes are not located at the same spots anymoreMutations are just a variationZygotes bring DNA from two different parent cells into the same cell—CLOSE PROXIMITYoThe only way recombination can occur is if it is in close proximityproducts of plants through meiosis are not gametes!!oThey are sporesoSpores divide by mitosisMake gametophytes (haploid)

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