Question

5. What happens to the DNA that is degraded by the RecBCD complex?

It is replaced by RecA.

It is replaced by DNA polymerase activity.

It is permanently lost.

It is unknown.

Answer 1

First option

RecBCD is a complex present in E.coli. It helps the bacterium to repair its degraded DNA. But this enzyme is unique because it can also degrade DNA, but not the DNA of E.coli, it degrades foreign DNA and protects the DNA of the bacterium.

RecBCD is an exonuclease. It works in the presence of either abundant ATP or abundant magnesium ions. With both these cofactors it has a different mechanism of action. With ATP, it first cleaves the DNA near chi terminus (present near 3') and with magnesium ions, it cleaves both the strands of DNA. When RecBCD completes it role and degrades the DNA, the DNA is then taken over by RecA.

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