Final answer:
The correct answer to the question is that the cleavage of LexA by RecA results in the derepression of the SOS response system, allowing the cell to repair damaged DNA.
Step-by-step explanation:
When damaged or single-stranded DNA activates RecA protein, this event triggers a cascade of reactions aimed at repairing the DNA damage. A crucial step in this process is the cleavage of the LexA repressor protein which leads to the derepression of the SOS system. Consequently, the SOS response enables the transcription of a number of genes involved in DNA repair processes, giving the cell a chance to fix the damage caused to its DNA.
The term 'SOS system' refers to a cellular response to DNA damage in bacteria that involves the induction of approximately 40 genes, including those responsible for DNA repair, error-prone DNA polymerases, and cell division inhibitors. The cleavage of LexA by activated RecA relieves the repression of these genes, allowing for their expression. Without the SOS response, cells would have higher rates of mutation and cell death due to unrepaired DNA damage.
In summary, the correct answer is that the activation of RecA protein leading to the cleavage of LexA results in derepression of the SOS system, which allows for an array of DNA repair mechanisms to be activated in response to damage.