The Holliday Model - The Holliday Model 1964 Molecular...

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The Holliday Model 1964 Molecular model of recombination: Holliday Model Named after Robin Holliday This model has continued to provide the basis for current thinking about recombination mechanisims, although the model has been modified in recent years. Original model: 1) Single-stranded nicks are introduced at the same position on both parental DNA molecules. 2) Each nicked strand then invades the other DNA molecule by complementary base pairing 3) Ligation produces a crossed-strand intermediate called a Holliday junction 4) Once a Holliday junction is formed, it can be resolved by nicking and rejoining of the crossed strands to yield recombinant or nonrecombinantheteroduplexes (Fig. 5.32). There is direct EM evidence for formation of the Holliday junction (Fig. 5.31) Recombinent heteroduplexes : Resulting DNA molecules are a combination of both parental DNA molecules. Nonrecombinent heteroduplexes : Except for heteroduplex region resulting DNA molecules contain only DNA from one parent molecule. Different heteroduplexes are formed because the Holliday junction may rotate into
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This document was uploaded on 11/03/2011 for the course BIOLOGY MCB2010 at Broward College.

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