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Phragmoplast
image:Phragmoplast.png, 300px, Phragmoplast and cell plate formation in a plant cell during cytokinesis. Left side: Phragmoplast forms and cell plate starts to assemble in the center of the cell. Towards the right: Phragmoplast enlarges in a donut-shape towards the outside of the cell, leaving behind mature cell plate in the center. The cell plate will transform into the new cell wall once cytokinesis is complete. The ''phragmoplast'' is a plant cell specific structure that forms during late cytokinesis. It serves as a scaffold for cell plate assembly and subsequent formation of a new cell wall separating the two daughter cells. The phragmoplast can only be observed in Phragmoplastophyta, a clade that includes the Coleochaetophyceae, Zygnematophyceae, Mesotaeniaceae, and Embryophyta (land plants). Some algae use another type of microtubule array, a phycoplast, during cytokinesis.P.H. Raven, R.F. Evert, S.E. Eichhorn (2005): ''Biology of Plants'', 7th Edition, W.H. Freeman and C ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phragmoplast
image:Phragmoplast.png, 300px, Phragmoplast and cell plate formation in a plant cell during cytokinesis. Left side: Phragmoplast forms and cell plate starts to assemble in the center of the cell. Towards the right: Phragmoplast enlarges in a donut-shape towards the outside of the cell, leaving behind mature cell plate in the center. The cell plate will transform into the new cell wall once cytokinesis is complete. The ''phragmoplast'' is a plant cell specific structure that forms during late cytokinesis. It serves as a scaffold for cell plate assembly and subsequent formation of a new cell wall separating the two daughter cells. The phragmoplast can only be observed in Phragmoplastophyta, a clade that includes the Coleochaetophyceae, Zygnematophyceae, Mesotaeniaceae, and Embryophyta (land plants). Some algae use another type of microtubule array, a phycoplast, during cytokinesis.P.H. Raven, R.F. Evert, S.E. Eichhorn (2005): ''Biology of Plants'', 7th Edition, W.H. Freeman and C ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cell Plate
image:Phragmoplast.png, 300px, Phragmoplast and cell plate formation in a plant cell during cytokinesis. Left side: Phragmoplast forms and cell plate starts to assemble in the center of the cell. Towards the right: Phragmoplast enlarges in a donut-shape towards the outside of the cell, leaving behind mature cell plate in the center. The cell plate will transform into the new cell wall once cytokinesis is complete. Cytokinesis in embryophyte, terrestrial plants occurs by cell plate formation. This process entails the delivery of Golgi-derived and endosomal vesicles carrying [ ell wall and cell membrane components to the plane of cell division and the subsequent fusion of these vesicles within this plate. After formation of an early tubulo-vesicular network at the center of the cell, the initially labile cell plate consolidates into a tubular network and eventually a fenestrated sheet. The cell plate grows outward from the center of the cell to the parental plasma membrane with whi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cytokinesis
Cytokinesis () is the part of the cell division process during which the cytoplasm of a single eukaryotic cell divides into two daughter cells. Cytoplasmic division begins during or after the late stages of nuclear division in mitosis and meiosis. During cytokinesis the spindle apparatus partitions and transports duplicated chromatids into the cytoplasm of the separating daughter cells. It thereby ensures that chromosome number and complement are maintained from one generation to the next and that, except in special cases, the daughter cells will be functional copies of the parent cell. After the completion of the telophase and cytokinesis, each daughter cell enters the interphase of the cell cycle. Particular functions demand various deviations from the process of symmetrical cytokinesis; for example in oogenesis in animals the ovum takes almost all the cytoplasm and organelles. This leaves very little for the resulting polar bodies, which in most species die without fu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phragmoplastophyta
The Phragmoplastophyta (Lecointre & Guyader 2006) are a proposed sister clade of the Klebsormidiaceae in the Streptophyte/Charophyte clade. The Phragmoplastophyta consist of the Charophycaea and another unnamed clade which contains the Coleochaetophyceae, Zygnematophyceae, Mesotaeniaceae, and Embryophytes (land plants). It is an important step in the emergence of land plants within the green algae. It is equivalent to the ZCC clade/grade, cladistically granting the Embryophyta. The mitosis of Phragmoplastophyta takes place via a phragmoplast. Another synapomorphy In phylogenetics, an apomorphy (or derived trait) is a novel character or character state that has evolved from its ancestral form (or plesiomorphy). A synapomorphy is an apomorphy shared by two or more taxa and is therefore hypothesized to hav ... of this clade is the synthesis of cellulose microfibrils by a complex of octameric cellulose synthetases. This complex crosses the plasma membrane and polymerizes mo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phycoplast
image:Phycoplast.png, Schematic representation of types of cytokinesis in the green algae: 1) Phycoplast formation with cleavage furrow (e.g. ''Chlamydomonas''); 2) Cleavage furrow and persistent telophase spindle (e.g. ''Klebsormidium''); 3) Phycoplast and cell plate formation (e.g. ''Fritschiella''); 4) Persistent telophase spindle/phragmoplast with cell plate formation (e.g. ''Coleochaete'') The phycoplast is a microtubule structure observed during cytokinesis in members of the '' Chlorophytina'', the largest and most well known subphylum of chlorophyte green algae. Cytokinesis in green algae occurs via a diverse range of mechanisms, including cleavage furrows in some algae and cell plates in others. Plants (=Chloroplastida) of the clade ''Phragmoplastophyta'' (a subgroup of charophytes which includes the land plants, desmids, water silk, stoneworts etc.) use structures called phragmoplasts to organize and guide the growing cell plate. In these plants, the microtubules of th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Embryophyta
The Embryophyta (), or land plants, are the most familiar group of green plants that comprise vegetation on Earth. Embryophytes () have a common ancestor with green algae, having emerged within the Phragmoplastophyta clade of green algae as sister of the Zygnematophyceae. The Embryophyta consist of the bryophytes plus the polysporangiophytes. Living embryophytes therefore include hornworts, liverworts, mosses, lycophytes, ferns, gymnosperms and flowering plants. The land plants have diplobiontic life cycles and it is accepted now that they emerged from freshwater, multi-celled algae. The embryophytes are informally called land plants because they live primarily in terrestrial habitats (with exceptional members who evolved to live once again in aquatic habitats), while the related green algae are primarily aquatic. Embryophytes are complex multicellular eukaryotes with specialized reproductive organs. The name derives from their innovative characteristic of nurturing the you ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 centrioles, except in the gametes, and a unique method of cell division involving the formation of a cell plate or phragmoplast that separates the new daughter cells. Characteristics of plant cells * Plant cells have cell walls, constructed outside the cell membrane and composed of cellulose, hemicelluloses, and pectin. Their composition contrasts with the cell walls of fungi, which are made of chitin, of bacteria, which are made of peptidoglycan and of archaea, which are made of pseudopeptidoglycan. In many cases lignin or suberin are secreted by the protoplast as secondary wall layers inside the primary ce ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mitosis
In cell biology, mitosis () is a part of the cell cycle in which replicated chromosomes are separated into two new nuclei. Cell division by mitosis gives rise to genetically identical cells in which the total number of chromosomes is maintained. Therefore, mitosis is also known as equational division. In general, mitosis is preceded by S phase of interphase (during which DNA replication occurs) and is often followed by telophase and cytokinesis; which divides the cytoplasm, organelles and cell membrane of one cell into two new cells containing roughly equal shares of these cellular components. The different stages of mitosis altogether define the mitotic (M) phase of an animal cell cycle—the division of the mother cell into two daughter cells genetically identical to each other. The process of mitosis is divided into stages corresponding to the completion of one set of activities and the start of the next. These stages are preprophase (specific to plant cells), propha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cell Wall
A cell wall is a structural layer surrounding some types of cells, just outside the cell membrane. It can be tough, flexible, and sometimes rigid. It provides the cell with both structural support and protection, and also acts as a filtering mechanism. Cell walls are absent in many eukaryotes, including animals, but are present in some other ones like fungi, algae and plants, and in most prokaryotes (except mollicute bacteria). A major function is to act as pressure vessels, preventing over-expansion of the cell when water enters. The composition of cell walls varies between taxonomic group and species and may depend on cell type and developmental stage. The primary cell wall of land plants is composed of the polysaccharides cellulose, hemicelluloses and pectin. Often, other polymers such as lignin, suberin or cutin are anchored to or embedded in plant cell walls. Algae possess cell walls made of glycoproteins and polysaccharides such as carrageenan and agar that are ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mesotaeniaceae
The Mesotaeniaceae are a small family of unicellular green algae known as the "saccoderm desmids". The Mesotaeniaceae appear to be sister or ancestral to the Zygnemataceae. The desmids are a deep branching group of Zygnemataceae. ''Spirotaenia'' was found to be a basal green alga. Genera The Mesotaeniaceae includes the following genera: * '' Ancylonema'' Berggren, 1872 * '' Cylindrocystis'' Meneghini ex De Bary, 1858 * '' Geniculus'' Prescott, 1967 * '' Mesotaenium'' Nägeli, 1849 * '' Netrium'' (Nägeli) Itzigsohn & Rothe, 1856 * '' Nucleotaenium'' Gontcharov & Melkonian, 2010 * '' Planotaenium'' (Ohtani) Petlovany & Palamar-Mordvintseva, 2009 * '' Roya'' West & G.S.West, 1896 * ''Spirotaenia ''Spirotaenia'' is a genus of basal green algae that may be sister to the Chlorokybophyceae. It was previously considered to be part of the Zygnemataceae. It is sexually conjugating, a mode of reproduction that was previously only known in th ...'' Brébisson, 1848 * '' Tortit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vesicle (biology)
In cell biology, a vesicle is a structure within or outside a cell, consisting of liquid or cytoplasm enclosed by a lipid bilayer. Vesicles form naturally during the processes of secretion (exocytosis), uptake ( endocytosis) and transport of materials within the plasma membrane. Alternatively, they may be prepared artificially, in which case they are called liposomes (not to be confused with lysosomes). If there is only one phospholipid bilayer, the vesicles are called '' unilamellar liposomes''; otherwise they are called ''multilamellar liposomes''. The membrane enclosing the vesicle is also a lamellar phase, similar to that of the plasma membrane, and intracellular vesicles can fuse with the plasma membrane to release their contents outside the cell. Vesicles can also fuse with other organelles within the cell. A vesicle released from the cell is known as an extracellular vesicle. Vesicles perform a variety of functions. Because it is separated from the cytosol, the i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cell Cycle
The cell cycle, or cell-division cycle, is the series of events that take place in a cell that cause it to divide into two daughter cells. These events include the duplication of its DNA (DNA replication) and some of its organelles, and subsequently the partitioning of its cytoplasm, chromosomes and other components into two daughter cells in a process called cell division. In cells with nuclei ( eukaryotes, i.e., animal, plant, fungal, and protist cells), the cell cycle is divided into two main stages: interphase and the mitotic (M) phase (including mitosis and cytokinesis). During interphase, the cell grows, accumulating nutrients needed for mitosis, and replicates its DNA and some of its organelles. During the mitotic phase, the replicated chromosomes, organelles, and cytoplasm separate into two new daughter cells. To ensure the proper replication of cellular components and division, there are control mechanisms known as cell cycle checkpoints after each of the key s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
