Cellulose is the primary component of a plant cell wall. Cellulose is a molecule made up of numerous glucose molecules bonded together. It makes up the majority of the plant cell wall and plays a key role in helping plants remain stiff and upright. In bacterial cell walls, the primary component is peptidoglycan. This is a polymer made up of amino acids and sugars. Chitin, proteins, and glucans are the primary components in fungal cells.