Quiz 22: Homologous Recombination

Which of the following statements is not true concerning homologous recombination? A)It can be intramolecular. B)It can be bimolecular. C)Only one cross-over event can occur. D)It results in genetic variation. E)It is a reciprocal event.

Which of the following techniques was key in demonstrating the presynapsis and synapsis steps of homologous recombination? A)S1 nuclease mapping B)exonuclease digestion C)DNA footprinting D)Southern Blot E)electron microscopy

Molecular modeling of RuvA and a Holliday junction showed that they form a _________ that favors rapid branch migration. A)square planar conformation B)L-shape conformation C)clover leaf conformation D)D loop conformation E)Y-shape conformation

West and colleagues used gel mobility shift assays to demonstrate that __________ could bind to and resolve Holliday junctions. A)RecA B)RuvA C)RuvB D)RuvC E)RecB

One mechanism by which gene conversion can occur in N.crassa during meiosis is _______. A)RecBCD B)mismatch repair C)double stranded break synthesis D)SOS repair E)excision repair

________________ recombination is a cross-over event that joins previously separated DNA segments.

The E.coli genome,on average,contains approximately __________chi sites that can be involved in homologous recombination.

___________ protein greatly enhances the binding of RecA to single stranded DNA.

During postsynapsis strand exchange in homologous recombination of E.coli,ATP is necessary for _______ clearance from the synapsing DNA.

RecBCD protein has ______________ activity that can nick dsDNA.

A ________ double helix is different than a Watson-Crick double helix in that the two strands are aligned side by side instead of intertwined.

RuvA and RuvB are involved in ________ of a Holliday junction during homologous recombination.

________resolvase clips DNA at the consensus sequence,5-(A/T)TT(G/C)-3 during RecBCD recombination repair.

In eukaryotes,_______ often includes homologous recombination as a way to increase genetic variation.

During mating between two strains of Neurospora crassa containing different alleles of the same gene one would expect a 1:1 genotypic ratio in progeny spores,however,approximately 0.1% of the time this ratio strays from the predicted.This phenomenon is called_____________ ___________________.

Spo11 creates __________ in DNA during homologous recombination in Saccharomyces cerevisiae.

Holliday junctions are intermediates in RecBCD recombination in E.coli.

Branch migration is a spontaneous process that takes place after a Holliday junction is formed.

The role of SSB in RecBCD homologous recombination appears to be to unwind the secondary structures found in dsDNA.

David Gonda and Charles Radding have provided experimental evidence that the minimum degree of homology necessary for efficient synapsis to occur during homologous recombination is between 30 and 151 bp.

E.coli RecA protein is only necessary for the presynapsis step of homologous recombination.

Since RecA is such a versatile protein,RecBCD is not really necessary for homologous recombination to occur.

ATPS is an unhydrolyzable ATP analog that was used along with glutaraldehyde by Parsons and West to trap Holliday junctions for gel mobility shift assays.

Both RuvA and RuvB have ATPase activity that drives the unwinding and rewinding of DNA during branch migration.

Branch migration is not necessary for efficient resolution of Holliday junctions.

Mutations in ruvC increase sensitivity to UV light due to defective recombination repair.

A conserved tyrosine residue is likely to be the catalytic amino acid in Spo11 and homologous proteins.

Double stranded break formation in mitotic recombination is followed by 35 exonuclease digestion of 3 ends at the break to yield 5 overhangs.

All organisms undergo homologous recombination as a way to increase genetic variation and help cope with DNA damage.

Gene conversion usually only occurs between nonallelic genes such as the MAT genes used to determine mating type in yeasts.