Objectives of DNA recombination. The different processes of DNA recombination: homologous recombination, site-specific recombination, transposition, illegitimate recombination, etc.
a pair of parental alleles is detected in the meiotic products.
Site-specific Recombination: Bacteriophage lambda integration in E. coli
A site-specific recombination reaction (eg. catalyzed by Int of bacteriophage lambda)
Duplication of the DNA sequence at a target site when a transposon is inserted
by a cointegrate intermediate.
Direct Repair:Reversal of O6 methyl G to G by methyltransferase
Effect of DNA damage on replication: (i) coding lesions won’t interfere with replication but may produce mutation, (ii) non-coding lesions will interfere with replication and may lead to formation of daughter-strand gaps (DSG) or double-strand breaks (DSB).
DSG and DSB may be repaired by recombination process, to be discussed in the following section.
Model for nonhomologous end-joining