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Following mitosis, two daughter cells form inside the parent cell, with the nucleus of each daughter cell moves to the side of the diatom where the new hypotheca will form. A microtubule center positions itself between the nucleus and the plasma membrane above which the new hypotheca will be placed.
In diatoms, fertilization gives rise to a zygote termed auxospore. Besides sexual reproduction and as a resting stage, the function of an auxospore is the restoration of the original cell size, as diatoms get progressively smaller during mitotic cell division. Auxospores divide by mitosis.
As a result, after each division cycle, the average size of diatom cells in the population gets smaller. Once such cells reach a certain minimum size, rather than simply divide, they reverse this decline by forming an auxospore, usually through meiosis and sexual reproduction, but exceptions exist. The auxospore expands in size to give rise to ...
Consequently, each division cycle decreases the average size of diatom cells in a population. When its size becomes too small, a dividing diatom cell produces an auxospore to expand its cell size back to that which is normal for vegetative cells. [2] Auxospores can also play a role in sexual reproduction in diatoms, and may be formed after ...
Pinnularia, like most diatoms, can reproduce by simple cell division. Nuclear division occurs by mitosis and cell divides into two parts. Each daughter receives one of the parent cell's thecae, which becomes that cell's epitheca. The cell then synthesizes a new hypotheca. Thus, one daughter is the same size as the parent, and one is slightly ...
Like other diatoms, cells of Chaetoceros are surrounded by siliceous cell walls known as frustules. Each frustule has four hollow processes called setae, or spines, that allow adjacent cells to link together and form colonies. [2] Colonies can form chains that are coiled, straight, or curved. Cell size can range from <10 um to 50 um. [5]
The Coscinodiscophyceae are a class(s) of diatoms. [1] They are similar to the Centrales, a traditional, paraphyletic subdivision of the heterokont algae known as diatoms. [2] [3] [4] The order is named for the shape of the cell walls (or valves or frustules) of centric diatoms, which are circular or ellipsoid in valve view.
The M phase can be either mitosis or meiosis depending on the type of cell. Germ cells , or gametes, undergo meiosis, while somatic cells will undergo mitosis. After the cell proceeds successfully through the M phase, it may then undergo cell division through cytokinesis.