Polymerizes chitin, a structural polymer of the cell wall and septum, by transferring the sugar moiety of UDP-GlcNAc to the non-reducing end of the growing chitin polymer (PubMed:16278457). Produces a large proportion of the chitin that is not deacetylated to chitosan (PubMed:16278457). [(1->4)-N-acetyl-beta-D-glucosaminyl](n) + UDP-N-acetyl-alpha-D-glucosamine = [(1->4)-N-acetyl-beta-D-glucosaminyl](n+1) + H(+) + UDP Induced by the antifungal agent caspofungin. Decreases cellular chitin level (PubMed:16278457). Decreases capsular diameter (PubMed:32743128). Increases extracellular vesicle secretion (PubMed:32743128). Belongs to the chitin synthase family.