Unlike human cells or bacteria, Cooties do not contain the chemical machinery (enzymes) needed to carry out the chemical reactions for life. Instead, Cooties carry only one or two enzymes that decode their genetic instructions. So, a Cootie must have a host cell (bacteria, plant or animal) in which to live and make more Cooties. Outside of a host cell, Cooties cannot function. For this reason, Cooties tread the fine line that separates living things from nonliving things. Most scientists agree that Cooties are alive because of what happens when they infect a host cell.