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A coal ball is a type of concretion, varying in shape from an imperfect sphere to a flat-lying, irregular slab.Coal balls were formed in Carboniferous Period swamps and mires, when peat was prevented from being turned into coal by the high amount of calcite surrounding the peat; the calcite caused it to be turned into stone instead.
Although they are outside the cells, the filaments of Labyrinthulomycetes are surrounded by a membrane. They are formed and connected with the cytoplasm by a unique organelle called a sagenogen or bothrosome. The cells are uninucleated and typically ovoid, and move back and forth along the amorphous network at speeds varying from 5-150 μm per ...
Descriptions dating from the 18th century attest to the fact that concretions have long been regarded as geological curiosities. Because of the variety of unusual shapes, sizes and compositions, concretions have been interpreted to be dinosaur eggs, animal and plant fossils (called pseudofossils), extraterrestrial debris or human artifacts.
Unlike the static nature typically depicted in textbooks, the plant cell nucleus is a highly dynamic structure, constantly moving around cells via actin networks and myosins. [1] The nucleus undergoes a characteristic program during cell division to guide asymmetric cell division, [ 2 ] but there are several stimuli that have been demonstrated ...
For a cell to move, it is necessary to bring a fresh supply of "feet" (proteins called integrins, which attach a cell to the surface on which it is crawling) to the front. It is likely that these feet are endocytosed [ 21 ] toward the rear of the cell and brought to the cell's front by exocytosis, to be reused to form new attachments to the ...
Structure of a plant cell. Plant cells are the cells present in green plants, photosynthetic eukaryotes of the kingdom Plantae.Their distinctive features include primary cell walls containing cellulose, hemicelluloses and pectin, the presence of plastids with the capability to perform photosynthesis and store starch, a large vacuole that regulates turgor pressure, the absence of flagella or ...
Also called beardtongue because of the appearance of its flowers, penstemon has pretty green, bronze or burgundy foliage and tall spikes on which the flowers appear. Some types readily self-seed ...
[54] Plant and algae cells are generally larger than many other cells; so cytoplasmic streaming is important in these types of cells. This is because the cell's extra volume requires cytoplasmic streaming in order to move organelles throughout the entire cell. [55] Organelles move along microfilaments in the cytoskeleton driven by myosin motors ...