ZOL 341 1st Edition Lecture 21 Outline of Last Lecture I Mutation II Frequency III Point mutations IV Effects of substitution mutations Outline of Current Lecture II Nucleotide excision and replacement III UV repair IV DNA recombination repair V Ploidy VI Nondisjunction VII Mosaicism Current Lecture Nucleotide excision and replacement the undamaged strand serves as a template to guide incorporation of the correct complementary nucleotide UV repair a short segment of DNA surrounding the photoproduct is excised new DNA is synthesized to replace the removed nucleotides DNA recombination repair DNA replication can skip the lesions by bypassing the damages sections leaving single stranded gaps recombination repair directs recombination of the incomplete segment with the complementary strand using the sister chromatid as the repair template ploidy euploid a number of chromosomes that is an exact multiple of the haploid number These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute eg 2n 3n aneuploid an uneven number of chromosomes eg 2n 1 2n 1 nondisjunction the failure of homologous chromosomes or sister chromatids to separate mosaicism being composed of cells of two genetically different types
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