Search results
Results From The WOW.Com Content Network
Some pennate diatoms also exhibit a fissure along their longitudinal axis. 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 .
Some pennate diatoms are capable of a type of locomotion called "gliding", which allows them to move across surfaces via adhesive mucilage secreted through a seamlike structure called the raphe. [ 60 ] [ 61 ] In order for a diatom cell to glide, it must have a solid substrate for the mucilage to adhere to.
Type of protist Movement mechanism Description Example Other examples Motile Flagellates: A flagellum (Latin for whip) is a lash-like appendage that protrudes from the cell body of some protists (as well as some bacteria).
The frustules of dead diatoms drift to the ocean floor where, over millions of years, they can build up as much as half a mile deep. [16] Diatoms uses silicon in the biogenic silica (BSiO 2) form, [17] which is taken up by the silicon transport protein to be predominantly used in constructing these protective cell wall structures. [18]
Navicula diatoms are highly motile and move through a gliding movement [3] [4] [5] This is done through excretion of extracellular polymeric substances (EPS). One form of EPS surrounds the outside of the cell and another is excreted through a slit in the frustule called a raphe, allowing the cell to glide along a track.
Fragilariopsis kerguelensis is a unicellular, phototrophic, microalga with a range in size of 10 - 80 μm. [3] It is encased in a heavily silicified cell wall, called the frustule, and is identified by its unique theca, raphe and striations, which distinguish it from other diatoms. [4]
The diatom Pseudo-nitzschia granii is a common responder to iron enrichment in iron-limited regions of the ocean. Pseudo-nitzschia species are bilaterally symmetrical pennate diatoms. Cell walls are made up of elongated silica frustules. The silica wall is fairly dense which leads to negative buoyancy, providing a number of advantages.
Medlin and co-workers erected a new class, Mediophyceae (which could be re-ranked a subclass if diatoms as a whole are ranked as a class rather than a phylum) for the "polar centric" diatoms, which they consider to be more closely related to the pennate rather than to other centric diatoms, a concept which has been followed or further adapted ...