Final answer:
Genetic recombination remains a random process because of the variable interaction between proteins like PRDM9 and recombination hotspots, as well as other complex genetic mechanisms. The randomness in these interactions is a fundamental aspect of biological diversity and is essential in processes such as the formation of B cells and their antibodies.
Step-by-step explanation:
Genetic recombination is a natural and random process due to the complexity and variability of genetic material. PRDM9 is a protein that binds to DNA at certain recombination hotspots, but its activity doesn't equate to a deterministic process. Indeed, the binding occurrence of PRDM9 can vary, partly due to the random motion of these proteins and their interactions with the hotspots. Additionally, not every protein variant will find its matching hotspot due to this randomness, and the hotspots themselves can vary between individuals.
Furthermore, in the production of B cells, the DNA recombinase acts to randomly excise gene segments, contributing to the diversity of the immune response. This randomness is essential, as it generates a vast array of possible VJ combinations, creating a unique variable chain for each B cell, while the constant domain remains the same across all antibodies.
Therefore, while PRDM9 plays a role in activating certain hotspots, genetic recombination encompasses a broader range of processes and variables, leading to different outcomes with each event. For mapping, using multiple methods can help accommodate the variability and provide a clearer genetic picture.