Biochem 3 Unit 3 Questions And Answers
2026 Update!!!
exchanges between molecules that share
homologous recombination
sequence similarity
In bacteria is the primary
repair function and can also occur during homologous recombination
conjugation
eukaryotes use homologous recombination for
repair; meiosis
and
In bacteria the primary function of homologous
recombination is the repair of stalled replication forks
stalled replication forks in bacteria can come unrepaired breaks from: base excision, radiation,
from…. damage
RecB and RecD helicase activity unwinds DNA,
RecB nuclease activity degrades both strands of
DNA past the break and degrading the 3’ end
more, RecC binds a Chi sequence and only the 5’
end continues to unwind and degrade, RecBCD
load RecA onto the 3’ overhang, loaded RecA
Steps of homologous recombination in bacteria: “strand invades” a homologous duplex creating
a triple helix, RuvA will then kick off third strand
which will pair with the 5’ strand creating a
holiday intermediate, RuvC cuts and ligates the
holiday intermediate, replication restart
primosome can come in and continue to
synthesize the recombinant strands.
RecB andD and ATP-dependent helicases
RecB has activity nuclease
RecC binds the site Chi
, 1009 sequences spread around the E.coli
Chi site
genome
RecA performs strand invasion
2026 Update!!!
exchanges between molecules that share
homologous recombination
sequence similarity
In bacteria is the primary
repair function and can also occur during homologous recombination
conjugation
eukaryotes use homologous recombination for
repair; meiosis
and
In bacteria the primary function of homologous
recombination is the repair of stalled replication forks
stalled replication forks in bacteria can come unrepaired breaks from: base excision, radiation,
from…. damage
RecB and RecD helicase activity unwinds DNA,
RecB nuclease activity degrades both strands of
DNA past the break and degrading the 3’ end
more, RecC binds a Chi sequence and only the 5’
end continues to unwind and degrade, RecBCD
load RecA onto the 3’ overhang, loaded RecA
Steps of homologous recombination in bacteria: “strand invades” a homologous duplex creating
a triple helix, RuvA will then kick off third strand
which will pair with the 5’ strand creating a
holiday intermediate, RuvC cuts and ligates the
holiday intermediate, replication restart
primosome can come in and continue to
synthesize the recombinant strands.
RecB andD and ATP-dependent helicases
RecB has activity nuclease
RecC binds the site Chi
, 1009 sequences spread around the E.coli
Chi site
genome
RecA performs strand invasion
