Now we do a search and conrm that it encodes a

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Unformatted text preview: ions In question 1, we identified the TE from the genome. Now we do a search and confirm that it encodes a transposase: Transposase ! Answer: It is a Class II, or DNA transposon, because it encodes a transposase. If it was a Class I, or retrotransposon, it might encode reverse transcriptase. TEs have mutagenic effects • TEs can insert into genes and disrupt their function • Transposition can lead to DNA rearrangements because it involves recombination. • recipro. Excision of cut-and-paste TEs can result in DNA damage if not repaired properly. • Homologous recombination between multiple copies of a transposon can also lead to DNA rearrangements. Barbara McClintock discovered TEs by studying multicolored (variegated) maize Figure 11.25 recom req physical exchange of dna This is the same Barbara McClintock who discovered that recombination involved physical exchange of DNA between chromosomes Maize variegation: Ac and Ds elements wild type + both are • DNA transposons • Two types • Ac (activator) elements carry transposase (autonomous) • Ac elements are wild type Maize variegation: Ac and Ds elements dissociator • Ds elements have deletions in the transposase gene (nonautonomous) • Ds elements only transpose when Ac elements are in the same cell dont carry own transposase in cell, they dont move, NONAUTONOMOUS Maize kernel pigment: The “C” locus Phenotype Genotype cc CC or Cc • Each kernel originates from a separate embryo • C is an allele...
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This document was uploaded on 02/25/2014.

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