A strain of E. coli is identified as having a null mutation of the RecA gene. What biological property do you expect to be absent in the mutant strain? What is the molecular basis for the missing property?

Key Concepts

RecA Protein Function

RecA is a crucial protein in bacteria that facilitates homologous recombination and DNA repair. It plays a key role in the SOS response, allowing cells to repair damaged DNA and maintain genomic integrity. A null mutation in the RecA gene results in the absence of this protein, impairing the cell's ability to effectively respond to DNA damage.

Homologous Recombination

Homologous recombination is a process by which genetic material is exchanged between similar or identical DNA molecules. This mechanism is essential for repairing double-strand breaks in DNA and for genetic diversity during cell division. Without RecA, the E. coli strain would be unable to perform this critical repair process, leading to increased susceptibility to mutations and genomic instability.

SOS Response

The SOS response is a global response to DNA damage in bacteria, activating a set of genes involved in DNA repair and mutagenesis. RecA protein is central to this response, as it helps to initiate the repair processes and regulate the expression of genes that facilitate DNA repair. In a RecA-deficient strain, the SOS response would be severely compromised, resulting in an inability to repair DNA damage effectively.