How do other types of substances cross the plasma membrane?

What is the main difference between the “head” and the “tails” of a phospholipid, both structurally and functionally? 32. Proteins are very diverse in both structure and function. – Sketch a generalized (“generic”) amino acid. What bond links two amino acids together? Sketch a generalized dipeptide. f) How do other types of substances cross the plasma membrane?