Question

What is the role of RecA and RAD 51 in homologous recombination (step 2)?

1) They promote the binding of single-stranded DNA to the homologous double-stranded DNA
2) They catalyze the formation of a joint molecule between the single-stranded DNA and the homologous double-stranded DNA
3) They facilitate the exchange of genetic material between the single-stranded DNA and the homologous double-stranded DNA
4) They stabilize the joint molecule formed between the single-stranded DNA and the homologous double-stranded DNA

Answer 1

RecA and RAD51 are essential proteins that facilitate the exchange of genetic material between single-stranded DNA and homologous double-stranded DNA during homologous recombination, a process vital for DNA double-strand break repair.

Step-by-step explanation:

The role of RecA and RAD51 in homologous recombination during the repair of a double-stranded DNA break is crucial for maintaining the integrity of the genetic material. These proteins function to facilitate the exchange of genetic material between the single-stranded DNA and the homologous double-stranded DNA. Specifically, RecA forms a nucleoprotein filament with single-stranded DNA and scans for homologous sequences in double-stranded DNA. Once it finds a match, the RecA-DNA filament promotes the pairing and strand invasion of these sequences,

which is an essential step in homologous recombination. RAD51, the eukaryotic homolog of RecA, plays a similar role in assisting the repair process by binding to the single-stranded DNA and promoting the exchange of strands between homologous DNA molecules. By facilitating strand invasion and exchange, these proteins ensure accurate repair of DNA double-strand breaks, which is critical for the survival and genetic stability of the species.