AP BIOLOGY

Detailed explanation-1: -There are four types of Membrane proteins: lipid-anchored, integral, peripheral, and auxiliary.

Detailed explanation-2: -The first three types in the Fig. 2 are common forms in integral membrane proteins, such as, transmembrane -helix protein, transmembrane -helical protein and transmembrane -sheet protein.

Detailed explanation-3: -Transmembrane proteins are the classic examples of intrinsic membrane proteins. These span the membrane, typically in an -helix conformation and can span the membrane multiple times. Some intergral membrane proteins use -barrels to cross the membrane.