Final answer:
The purpose of treating cells with alcohol when using an EIA to study microtubules is to make the cell membrane permeable, allowing antibodies to enter the cell and bind to specific targets.
Step-by-step explanation:
When using an Enzyme Immunoassay (EIA) to study microtubules or other structures inside a cell, cells are first chemically fixed to preserve their structures and stop all biochemical reactions. After fixation, the cells are treated with alcohol for a specific purpose. The alcohol treatment in immunocytochemistry (ICC), a technique related to EIA, is used to make the cell membrane permeable so that antibodies can penetrate the cell and bind to their specific targets, such as microtubules and other intracellular components. This permeabilization step is crucial because cell membranes are generally impervious to large molecules like antibodies without such treatment. Through alcohol etching, antibodies can access the inside of the cell and adhere to their corresponding antigens, facilitating their detection and visualization.