Once free radicals like superoxide or hydroxyl radical (.OH) enter the picture, they initiate a chain reaction called lipid peroxidation
that rapidly chews up membranes. Without membranes, the cell can't
maintain separate compartments in which to partition all its stuff. And
as we all know, without a place for your stuff, life falls apart.
The ROS Zombification Process. Lipid radicals create more lipid radicals. Before you know it, they've taken over.
Lipid peroxidation is devastating and rapid, because every lipid radical formed in the process can burn another lipid molecule. And so it goes.
It's like zombies or body-snatchers. Until something comes along to
terminate the process by sopping up all those rad electrons, the fire
will just keep burning.