Alcohol kills bacteria because it disrupts their cell membranes and denatures their proteins. Alcohol molecules are amphiphilic, meaning they have both water- and fat-attracting properties, allowing them to break down the bacterial cell's protective membrane composed of fats and water molecules. This membrane breakdown causes the core components of the bacteria, including proteins essential for survival and function, to lose their structure and dissolve. The denaturation of bacterial proteins makes them nonfunctional, ultimately causing the bacteria to die quickly as their cellular structure and essential biological functions collapse. This process is effective at alcohol concentrations between about 60% and 90% and applies to both ethyl alcohol (ethanol) and isopropyl alcohol commonly found in disinfectants and hand sanitizers.