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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
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
• Ac elements are wild
type Maize variegation: Ac and Ds elements dissociator • Ds elements have
deletions in the
• Ds elements only
transpose when Ac
elements are in the
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.
- Fall '14