Combination of cellulose chains to form a cellulose microfibril Studies show that 60 to 70 individual molecules may combine to form a microfibril. Within one of these structures, individual cellulose molecules are held in an unbent parallel form by H bonds between the adjacent glucose chains. These individual cellulose microfibrils are large enough to be viewed in the electron microscope as fine, dense lines in sectioned cell walls. There are other monosacchrides which make wall fibers. Callose is a regular wall constituent in certain fungi, including yeasts.
Chitin is also a primary cell wall constituent of fungi.
In dicots, the main hemicellulose is xyloglucan, which is structured mainly from a glucose backbon with xylose chains attached to it. The main structural glycoprotein family in cell walls, the extensis , contain a large proportion of the modified amino acid hydroxyproline. Also existant in significant amounts are serine and lysine. These carbohydrates are usually short linear chains rangind from one to four sugar units attached to the polypeptide backbone. Another important substance in plant cell structure is lignin.