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Thylakoid Space
Thylakoids are membrane-bound compartments inside chloroplasts and cyanobacteria. They are the site of the light-dependent reactions of photosynthesis. Thylakoids consist of a thylakoid membrane surrounding a thylakoid lumen. Chloroplast thylakoids frequently form stacks of disks referred to as grana (singular: ''granum''). Grana are connected by intergranal or stromal thylakoids, which join granum stacks together as a single functional compartment. In thylakoid membranes, chlorophyll pigments are found in packets called quantasomes. Each quantasome contains 230 to 250 chlorophyll molecules. Etymology The word ''Thylakoid'' comes from the Greek word ''thylakos'' or ''θύλακος'', meaning "sac" or "pouch". Thus, ''thylakoid'' means "sac-like" or "pouch-like". Structure Thylakoids are membrane-bound structures embedded in the chloroplast stroma. A stack of thylakoids is called a granum and resembles a stack of coins. Membrane The thylakoid membrane is the site of th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phospholipids
Phospholipids are a class of lipids whose molecule has a hydrophilic "head" containing a phosphate group and two hydrophobic "tails" derived from fatty acids, joined by an alcohol residue (usually a glycerol molecule). Marine phospholipids typically have omega-3 fatty acids EPA and DHA integrated as part of the phospholipid molecule. The phosphate group can be modified with simple organic molecules such as choline, ethanolamine or serine. Phospholipids are a key component of all cell membranes. They can form lipid bilayers because of their amphiphilic characteristic. In eukaryotes, cell membranes also contain another class of lipid, sterol, interspersed among the phospholipids. The combination provides fluidity in two dimensions combined with mechanical strength against rupture. Purified phospholipids are produced commercially and have found applications in nanotechnology and materials science. The first phospholipid identified in 1847 as such in biological tissues was ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arabidopsis Thaliana
''Arabidopsis thaliana'', the thale cress, mouse-ear cress or arabidopsis, is a small plant from the mustard family (Brassicaceae), native to Eurasia and Africa. Commonly found along the shoulders of roads and in disturbed land, it is generally considered a weed. A winter annual with a relatively short lifecycle, ''A. thaliana'' is a popular model organism in plant biology and genetics. For a complex multicellular eukaryote, ''A. thaliana'' has a relatively small genome of around 135 Base pair#Length measurements, megabase pairs. It was the first plant to have its genome sequenced, and is an important tool for understanding the molecular biology of many plant traits, including flower development and phototropism, light sensing. Description ''Arabidopsis thaliana'' is an annual plant, annual (rarely biennial plant, biennial) plant, usually growing to 20–25 cm tall. The leaf, leaves form a rosette at the base of the plant, with a few leaves also on the flowering Plant ste ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chlamydomonas
''Chlamydomonas'' ( ) is a genus of green algae consisting of about 150 species of unicellular organism, unicellular flagellates, found in stagnant water and on damp soil, in freshwater, seawater, and even in snow as "snow algae". ''Chlamydomonas'' is used as a model organism for molecular biology, especially studies of flagellum, flagellar motility and chloroplast dynamics, biogenesis, and genetics. One of the many striking features of ''Chlamydomonas'' is that it contains ion channels (channelrhodopsins) that are directly activated by light. Some FLU (plant gene), regulatory systems of ''Chlamydomonas'' are more complex than their Homology (biology), homologs in Gymnosperms, with evolutionarily related Regulation of gene expression, regulatory proteins being larger and containing additional Protein domain, domains. Molecular phylogeny studies indicated that the traditional genus ''Chlamydomonas'' as defined using morphological data, was polyphyletic within Volvocales. Many s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Etiolation
Etiolation is a process in flowering plants grown in partial or complete absence of light. It is characterized by long, weak stems; smaller leaves due to longer internodes; and a pale yellow color (chlorosis). The development of seedlings in the dark is known as "skotomorphogenesis" and leads to etiolated seedlings. Effects Etiolation increases the likelihood that a plant will reach a light source, often from under the soil, leaf litter, or shade from competing plants. The growing tips are strongly attracted to light and will elongate towards it. The pale color results from a lack of chlorophyll. Some of the changes that occur include # elongation of stems and leaves; # weakening of cell walls in stems and leaves; # longer internodes, hence fewer leaves per unit length of stem; # chlorosis, a pale yellowish-white coloration. De-etiolation is the transition of seedlings from below-ground growth to above-ground growth form. Causes Etiolation is controlled by the plant hormone ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Etioplast
Etioplasts are an intermediate type of plastid that develop from proplastids that have not been exposed to light, and convert into chloroplasts upon exposure to light. They are usually found in stem and leaf tissue of flowering plants (Angiosperms) grown either in complete darkness, or in extremely low-light conditions. Etymology The word " etiolated" (from French word étioler — "straw") was first coined by Erasmus Darwin in 1791 to describe the white and straw-like appearance of dark-grown plants. However, the term "etioplast" did not exist until 1967 when it was invented by John T. O. Kirk and Richard A. E. Tilney-Bassett to distinguish etioplasts from proplastids, their precursors. Structure Etioplasts are characterized by the absence of chlorophyll and the presence of a complicated structure called a prolamellar body (PLB). Usually, a single one is present in each etioplast. PLB is composed of symmetrically arranged, tetrahedrally-branched tubules and may contain ri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Seedling
A seedling is a young sporophyte developing out of a plant embryo from a seed. Seedling development starts with germination of the seed. A typical young seedling consists of three main parts: the radicle (embryonic root), the hypocotyl (embryonic Shoot (botany), shoot), and the cotyledons (seed leaves). The two classes of flowering plants (angiosperms) are distinguished by their numbers of seed leaves: monocotyledons (monocots) have one blade-shaped cotyledon, whereas dicotyledons (dicots) possess two round cotyledons. Gymnosperms are more varied. For example, pine seedlings have up to eight cotyledons. The seedlings of some flowering plants have no cotyledons at all. These are said to be acotyledons. The plumule is the part of a seed embryo that develops into the shoot bearing the first true leaves of a plant. In most seeds, for example the sunflower, the plumule is a small conical structure without any leaf structure. Growth of the plumule does not occur until the cotyledon ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Proplastid
A plastid is a membrane-bound organelle found in the cells of plants, algae, and some other eukaryotic organisms. Plastids are considered to be intracellular endosymbiotic cyanobacteria. Examples of plastids include chloroplasts (used for photosynthesis); chromoplasts (used for synthesis and storage of pigments); leucoplasts (non-pigmented plastids, some of which can differentiate); and apicoplasts (non-photosynthetic plastids of apicomplexa derived from secondary endosymbiosis). A permanent primary endosymbiosis event occurred about 1.5 billion years ago in the Archaeplastida cladeland plants, red algae, green algae and glaucophytesprobably with a cyanobiont, a symbiotic cyanobacteria related to the genus '' Gloeomargarita''. Another primary endosymbiosis event occurred later, between 140 and 90 million years ago, in the photosynthetic plastids '' Paulinella'' amoeboids of the cyanobacteria genera ''Prochlorococcus'' and '' Synechococcus'', or the "PS-clade". Secondary ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electron Tomography
Electron tomography (ET) is a tomography technique for obtaining detailed 3D structures of sub-cellular, macro-molecular, or materials specimens. Electron tomography is an extension of traditional transmission electron microscopy and uses a transmission electron microscope to collect the data. In the process, a beam of electrons is passed through the sample at incremental degrees of rotation around the center of the target sample. This information is collected and used to assemble a three-dimensional image of the target. For biological applications, the typical resolution of ET systems are in the 5–20 nm range, suitable for examining supra-molecular multi-protein structures, although not the secondary and tertiary structure of an individual protein or polypeptide. Recently, atomic resolution in 3D electron tomography reconstructions has been demonstrated. BF-TEM and ADF-STEM tomography In the field of biology, bright-field transmission electron microscopy (BF-TEM) and high-res ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Photophosphorylation
In the process of photosynthesis, the phosphorylation of ADP to form ATP using the energy of sunlight is called photophosphorylation. Cyclic photophosphorylation occurs in both aerobic and anaerobic conditions, driven by the main primary source of energy available to living organisms, which is sunlight. All organisms produce a phosphate compound, ATP, which is the universal energy currency of life. In photophosphorylation, light energy is used to pump protons across a biological membrane, mediated by flow of electrons through an electron transport chain. This stores energy in a proton gradient. As the protons flow back through an enzyme called ATP synthase, ATP is generated from ADP and inorganic phosphate. ATP is essential in the Calvin cycle to assist in the synthesis of carbohydrates from carbon dioxide and NADPH. ATP and reactions Both the structure of ATP synthase and its underlying gene are remarkably similar in all known forms of life. ATP synthase is powered by a trans ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thylakoid Membrane
Thylakoids are membrane-bound compartments inside chloroplasts and cyanobacteria. They are the site of the light-dependent reactions of photosynthesis. Thylakoids consist of a thylakoid membrane surrounding a thylakoid lumen. Chloroplast thylakoids frequently form stacks of disks referred to as grana (singular: ''granum''). Grana are connected by intergranal or stromal thylakoids, which join granum stacks together as a single functional compartment. In thylakoid membranes, chlorophyll pigments are found in packets called quantasomes. Each quantasome contains 230 to 250 chlorophyll molecules. Etymology The word ''Thylakoid'' comes from the Greek word ''thylakos'' or ''θύλακος'', meaning "sac" or "pouch". Thus, ''thylakoid'' means "sac-like" or "pouch-like". Structure Thylakoids are membrane-bound structures embedded in the chloroplast stroma. A stack of thylakoids is called a granum and resembles a stack of coins. Membrane The thylakoid membrane is the site of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lumen (anatomy)
In biology, a lumen (: lumina) is the inside space of a tubular structure, such as an artery or intestine. It comes . It can refer to: *the interior of a vessel, such as the central space in an artery, vein or capillary through which blood flows *the interior of the gastrointestinal tract *the pathways of the bronchi in the lungs *the interior of renal tubules and urinary collecting ducts *the pathways of the female genital tract, starting with a single pathway of the vagina, splitting up in two lumina in the uterus, both of which continue through the fallopian tubes *the fluid-filled cavity forming in the blastocyst during pre-implantation development called the blastocoel In cell biology, lumen is a membrane-defined space that is found inside several organelles, cellular components, or structures, including thylakoid, endoplasmic reticulum, Golgi apparatus, lysosome, mitochondrion, and microtubule. Transluminal procedures ''Transluminal procedures'' are procedures occur ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
