sentences:  This is known as a raphe, and is involved in gliding movements made by diatom cells; motile diatoms always possess a raphe.In terms of cell cycle, vegetative cells are diploid and undergo mitosis during normal cell division.Periodically, meiosis produces morphologically identical haploid gametes (isogametes), which fuse to produce a (sometimes binucleate) zygote that develops into an auxospore (from which full-sized vegetative cells are produced).