What property of rbc dooms them to a limited life span of about 120 days?

Red blood cells (RBCs) have a limited lifespan of about 120 days primarily due to their lack of a nucleus and organelles, which prevents them from repairing themselves or synthesizing new proteins. As they age, their membrane becomes more fragile, making them susceptible to damage and hemolysis as they pass through the microvasculature. Additionally, the accumulation of oxidative damage over time contributes to their decline in functionality and ultimately leads to their removal by the spleen and liver.