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Scytothamnus Australis
''Scytothamnus australis'' is a brown alga species in the genus ''Scytothamnus'' found in New Zealand. It is a sulphated polysaccharide and the type species in the genus. The species contains the phlorotannins trifucol, tetrafucol A, tetrafucol B, cis-pentafucol A, diphlorethol A and triphlorethol A. Distribution ''Scytothamnus australis'' has a southern circumpolar distribution and has been recorded to have been present from the waters of southern Australia, New Zealand and Chile. Description ''Scytothamnus australis'' is a larger, more robust species than ''Scytothamnus fasciculatus'', but possesses a similar branching pattern and broadly comparable vegetative anatomy. Cell structure As with the other species of ''Scytothamnus'', ''Scytothamnus australis'' has a stellate (star-shaped) chloroplast with a central pyrenoid and is perforated by channels of cytoplasm. Reproductive structure ''Scytothamnus australis'' has a unilocular sporangia reproductive structure which me ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Joseph Dalton Hooker
Sir Joseph Dalton Hooker (30 June 1817 – 10 December 1911) was a British botanist and explorer in the 19th century. He was a founder of geographical botany and Charles Darwin's closest friend. For twenty years he served as director of the Royal Botanical Gardens, Kew, succeeding his father, William Jackson Hooker, and was awarded the highest honours of British science. Biography Early years Hooker was born in Halesworth, Suffolk, England. He was the second son of the famous botanist Sir William Jackson Hooker, Regius Professor of Botany, and Maria Sarah Turner, eldest daughter of the banker Dawson Turner and sister-in-law of Francis Palgrave. From age seven, Hooker attended his father's lectures at Glasgow University, taking an early interest in plant distribution and the voyages of explorers like Captain James Cook. He was educated at the Glasgow High School and went on to study medicine at Glasgow University, graduating M.D. in 1839. This degree qualified him for ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thallus
Thallus (plural: thalli), from Latinized Greek (), meaning "a green shoot" or "twig", is the vegetative tissue of some organisms in diverse groups such as algae, fungi, some liverworts, lichens, and the Myxogastria. Many of these organisms were previously known as the thallophytes, a polyphyletic group of distantly related organisms. An organism or structure resembling a thallus is called thalloid, thallodal, thalliform, thalline, or thallose. A thallus usually names the entire body of a multicellular non-moving organism in which there is no organization of the tissues into organs. Even though thalli do not have organized and distinct parts (leaves, roots, and stems) as do the vascular plants, they may have analogous structures that resemble their vascular "equivalents". The analogous structures have similar function or macroscopic structure, but different microscopic structure; for example, no thallus has vascular tissue. In exceptional cases such as the Lemnoideae, where ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gametogenesis
Gametogenesis is a biological process by which diploid or haploid precursor cells undergo cell division and differentiation to form mature haploid gametes. Depending on the biological life cycle of the organism, gametogenesis occurs by meiotic division of diploid gametocytes into various gametes, or by mitosis. For example, plants produce gametes through mitosis in gametophytes. The gametophytes grow from haploid spores after sporic meiosis. The existence of a multicellular, haploid phase in the life cycle between meiosis and gametogenesis is also referred to as alternation of generations. It is the biological process of gametogenesis; cells that are haploid or diploid divide to create other cells. matured haploid gametes. It can take place either through mitosis or meiotic division of diploid gametocytes into different depending on an organism's biological life cycle, gametes. For instance, gametophytes in plants undergo mitosis to produce gametes. Both male and female have diff ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Physodes
Phlorotannins are a type of tannins found in brown algae such as kelps and rockweeds or sargassacean species, and in a lower amount also in some red algae. Contrary to hydrolysable or condensed tannins, these compounds are oligomers of phloroglucinol (polyphloroglucinols). As they are called tannins, they have the ability to precipitate proteins. It has been noticed that some phlorotannins have the ability to oxidize and form covalent bonds with some proteins. In contrast, under similar experimental conditions three types of terrestrial tannins (procyanidins, profisetinidins, and gallotannins) apparently did not form covalent complexes with proteins. These phenolic compounds are integral structural components of cell walls in brown algae, but they also seem to play many other secondary ecological roles such as protection from UV radiation and defense against grazing. Biosynthesis and localization Most of the phlorotannins' biosynthesis is still unknown, but it appears the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eyespot Apparatus
The eyespot apparatus (or '' stigma'') is a photoreceptive organelle found in the flagellate or (motile) cells of green algae and other unicellular photosynthetic organisms such as euglenids. It allows the cells to sense light direction and intensity and respond to it, prompting the organism to either swim towards the light (positive phototaxis), or away from it (negative phototaxis). A related response ("photoshock" or photophobic response) occurs when cells are briefly exposed to high light intensity, causing the cell to stop, briefly swim backwards, then change swimming direction. Eyespot-mediated light perception helps the cells in finding an environment with optimal light conditions for photosynthesis. Eyespots are the simplest and most common "eyes" found in nature, composed of photoreceptors and areas of bright orange-red red pigment granules. Signals relayed from the eyespot photoreceptors result in alteration of the beating pattern of the flagella, generating a pho ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chloroplast
A chloroplast () is a type of membrane-bound organelle known as a plastid that conducts photosynthesis mostly in plant and algal cells. The photosynthetic pigment chlorophyll captures the energy from sunlight, converts it, and stores it in the energy-storage molecules ATP and NADPH while freeing oxygen from water in the cells. The ATP and NADPH is then used to make organic molecules from carbon dioxide in a process known as the Calvin cycle. Chloroplasts carry out a number of other functions, including fatty acid synthesis, amino acid synthesis, and the immune response in plants. The number of chloroplasts per cell varies from one, in unicellular algae, up to 100 in plants like ''Arabidopsis'' and wheat. A chloroplast is characterized by its two membranes and a high concentration of chlorophyll. Other plastid types, such as the leucoplast and the chromoplast, contain little chlorophyll and do not carry out photosynthesis. Chloroplasts are highly dynamic—they circulat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Flagellate
A flagellate is a cell or organism with one or more whip-like appendages called flagella. The word ''flagellate'' also describes a particular construction (or level of organization) characteristic of many prokaryotes and eukaryotes and their means of motion. The term presently does not imply any specific relationship or classification of the organisms that possess flagella. However, the term "flagellate" is included in other terms (such as "dinoflagellate" and "choanoflagellata") which are more formally characterized. Form and behavior Flagella in eukaryotes are supported by microtubules in a characteristic arrangement, with nine fused pairs surrounding two central singlets. These arise from a basal body. In some flagellates, flagella direct food into a cytostome or mouth, where food is ingested. Flagella often support hairs, called mastigonemes, or contain rods. Their ultrastructure plays an important role in classifying eukaryotes. Among protoctists and microscopic anima ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chloroplasts
A chloroplast () is a type of membrane-bound organelle known as a plastid that conducts photosynthesis mostly in plant cell, plant and algae, algal cells. The photosynthetic pigment chlorophyll captures the energy from sunlight, converts it, and stores it in the energy-storage molecules Adenosine triphosphate, ATP and NADPH while freeing oxygen from water in the cells. The ATP and NADPH is then used to make organic molecules from carbon dioxide in a process known as the Calvin cycle. Chloroplasts carry out a number of other functions, including fatty acid synthesis, amino acid synthesis, and the immune response in plants. The number of chloroplasts per cell varies from one, in unicellular algae, up to 100 in plants like ''Arabidopsis'' and wheat. A chloroplast is characterized by Chloroplast membrane, its two membranes and a high concentration of chlorophyll. Other plastid types, such as the leucoplast and the chromoplast, contain little chlorophyll and do not carry out photos ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spores
In biology, a spore is a unit of sexual or asexual reproduction that may be adapted for dispersal and for survival, often for extended periods of time, in unfavourable conditions. Spores form part of the life cycles of many plants, algae, fungi and protozoa. Bacterial spores are not part of a sexual cycle, but are resistant structures used for survival under unfavourable conditions. Myxozoan spores release amoeboid infectious germs ("amoebulae") into their hosts for parasitic infection, but also reproduce within the hosts through the pairing of two nuclei within the plasmodium, which develops from the amoebula. In plants, spores are usually haploid and unicellular and are produced by meiosis in the sporangium of a diploid sporophyte. Under favourable conditions the spore can develop into a new organism using mitotic division, producing a multicellular gametophyte, which eventually goes on to produce gametes. Two gametes fuse to form a zygote which develops into a new spor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Flagella
A flagellum (; ) is a hairlike appendage that protrudes from certain plant and animal sperm cells, and from a wide range of microorganisms to provide motility. Many protists with flagella are termed as flagellates. A microorganism may have from one to many flagella. A gram-negative bacterium ''Helicobacter pylori'' for example uses its multiple flagella to propel itself through the mucus lining to reach the stomach epithelium, where it may cause a gastric ulcer to develop. In some bacteria the flagellum can also function as a sensory organelle, being sensitive to wetness outside the cell. Across the three domains of Bacteria, Archaea, and Eukaryota the flagellum has a different structure, protein composition, and mechanism of propulsion but shares the same function of providing motility. The Latin word means " whip" to describe its lash-like swimming motion. The flagellum in archaea is called the archaellum to note its difference from the bacterial flagellum. Eukaryoti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pith
Pith, or medulla, is a tissue in the stem Stem or STEM may refer to: Plant structures * Plant stem, a plant's aboveground axis, made of vascular tissue, off which leaves and flowers hang * Stipe (botany), a stalk to support some other structure * Stipe (mycology), the stem of a mushro ...s of vascular plants. Pith is composed of soft, spongy ground tissue#Parenchyma, parenchyma cells, which in some cases can store starch. In eudicotyledons, pith is located in the center of the stem. In monocotyledons, it extends also into flowering stems and roots. The pith is encircled by a ring of xylem; the xylem, in turn, is encircled by a ring of phloem. While new pith growth is usually white or pale in color, as the tissue ages it commonly darkens to a deeper brown color. In trees pith is generally present in young growth, but in the trunk and older branches the pith often gets replaced – in great part – by xylem. In some plants, the pith in the middle of the stem may dry out ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cortex (botany)
In botany, a cortex is an outer layer of a stem or root in a vascular plant, lying below the epidermis but outside of the vascular bundles. The cortex is composed mostly of large thin-walled parenchyma cells of the ground tissue system and shows little to no structural differentiation. The outer cortical cells often acquire irregularly thickened cell walls, and are called collenchyma cells. Plants Stems and branches In the three dimensional structure of herbaceous stems, the epidermis, cortex and vascular cambium form concentric cylinders around the inner cylindrical core of pith. Some of the outer cortical cells may contain chloroplasts, giving them a green color. They can therefore produce simple carbohydrates through photosynthesis. In woody plants, the cortex is located between the periderm (bark) and the vascular tissue (phloem, in particular). It is responsible for the transportation of materials into the central cylinder of the root through diffusion and may als ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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