Ethanol's ability to cross cell membranes is a topic of interest due to its unique properties. Despite being hydrophilic, ethanol can diffuse through phospholipid bilayers more easily than expected. This is attributed to its small size and the presence of a two-carbon alkyl group, which reduces its polarity compared to water. While water, a small and highly polar molecule, can diffuse freely through lipid membranes, ethanol's larger size and lower polarity allow it to penetrate cell membranes effectively. Ethanol does not typically require transport proteins for this process, as small, uncharged molecules can often diffuse across membranes without assistance. Understanding these characteristics is crucial for comprehending ethanol's impact on cellular functions.