Question

all of the following molecules can be found in extracellular structures except collagen. peptidoglycans. polysaccharides. cellulose. tubulin.

Explanation:

Collagen is a major component of the extracellular matrix in animals. Peptidoglycans are in bacterial cell - walls (extracellular for bacteria). Polysaccharides like cellulose are part of plant cell walls (extracellular). Tubulin is a protein that forms microtubules inside the cell, not an extracellular molecule.

Answer:

E. tubulin