Info

Complete new strand

Old strand

FIGURE 14.23 RecA and Recombination Repair

Since DNA damage stalls the replication enzymes, thymine dimers create large single-stranded gaps (green strand). The other strand (light pink) can be replicated as usual. To repair the gap, RecA directs crossovers on both sides of the single-stranded region. This transfers the gap to another DNA molecule where the correct complementary strand is present. The gap can now be filled in by DNA polymerase. Notice that the thymine dimer is not repaired during this process.

Recombination via

RecA PROTEIN

This DNA molecule is still damaged, but no longer has a gap *__

Gap can be filled in since opposite strand is undamaged

Single-stranded DNA

RecA

Ac.tival.ed form of RecA

LexA dimer represses

SOS system

Gene of SOS system

LexA dimer represses

SOS system

Gene of SOS system

Cleavage of LexA

PROMoteD BY ACTIVE FOrm OF RecA

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