Membranes contain large amounts of lipids, which are notoriously hydrophobic (water and oil don't mix). The membrane-spanning regions of membrane proteins are typically alpha helices, made of hydrophobic amino acids.
Florence, for example, hosted a brilliant period of musico-theatrical innovation at the dawn of the seventeenth century that led to the flowering of early opera. Rome continued to influence sacred music and for a time became an important center of opera, several types of vocal chamber music, and instrumental music. Venice, a leading musical city throughout the seventeenth century, nurtured the development of opera, as did Naples in the eighteenth century.
Within the categories of the classic SATB (soprano, alto, tenor, bass) there are many variations. Choral singers usually describe themselves as 1st or 2nd within their voice type, depending on which part of the range they prefer, and composers can write choral music for up to 10 parts.