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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.
Chlorophyta or Prasinophyta is a taxon of green algae informally called chlorophytes. The name is used in two very different senses, so care is needed to determine the use by a particular author. In older classification systems, it refers to a highly paraphyletic group of all the green algae within the green plants (Viridiplantae) and thus includes about 7,000 species of mostly aquatic photosynthetic eukaryotic organisms. In newer classifications, it refers to the sister clade of the streptophytes/charophytes. The clade Streptophyta consists of the Charophyta in which the Embryophyta emerged. In this latter sense the Chlorophyta includes only about 4,300 species. About 90% of all known species live in freshwater. Like the land plants, green algae contain chlorophyll a and chlorophyll b and store food as starch in their plastids.
A diatom is any member of a large group comprising several genera of algae, specifically microalgae, found in the oceans, waterways and soils of the world. Living diatoms make up a significant portion of the Earth's biomass: they generate about 20 to 50 percent of the oxygen produced on the planet each year, take in over 6.7 billion metric tons of silicon each year from the waters in which they live, and constitute nearly half of the organic material found in the oceans. The shells of dead diatoms can reach as much as a half-mile deep on the ocean floor, and the entire Amazon basin is fertilized annually by 27 million tons of diatom shell dust transported by transatlantic winds from the African Sahara, much of it from the Bodélé Depression, which was once made up of a system of fresh-water lakes.
The choanoflagellates are a group of free-living unicellular and colonial flagellate eukaryotes considered to be the closest living relatives of the animals. Choanoflagellates are collared flagellates, having a funnel shaped collar of interconnected microvilli at the base of a flagellum. Choanoflagellates are capable of both asexual and sexual reproduction. They have a distinctive cell morphology characterized by an ovoid or spherical cell body 3–10 µm in diameter with a single apical flagellum surrounded by a collar of 30–40 microvilli. Movement of the flagellum creates water currents that can propel free-swimming choanoflagellates through the water column and trap bacteria and detritus against the collar of microvilli, where these foodstuffs are engulfed. This feeding provides a critical link within the global carbon cycle, linking trophic levels. In addition to their critical ecological roles, choanoflagellates are of particular interest to evolutionary biologists studying the origins of multicellularity in animals. As the closest living relatives of animals, choanoflagellates serve as a useful model for reconstructions of the last unicellular ancestor of animals.
Chromista is a biological kingdom consisting of single-celled and multicellular eukaryotic species that share similar features in their photosynthetic organelles (plastids). It includes all protists whose plastids contain chlorophyll c, such as some algae, diatoms, oomycetes, and protozoans. It is probably a polyphyletic group whose members independently arose as a separate evolutionary group from the common ancestor of all eukaryotes. As it is assumed the last common ancestor already possessed chloroplasts of red algal origin, the non-photosynthetic forms evolved from ancestors able to perform photosynthesis. Their plastids are surrounded by four membranes, and are believed to have been acquired from some red algae.
Fucoxanthin is a xanthophyll, with formula C42H58O6. It is found as an accessory pigment in the chloroplasts of brown algae and most other heterokonts, giving them a brown or olive-green color. Fucoxanthin absorbs light primarily in the blue-green to yellow-green part of the visible spectrum, peaking at around 510-525 nm by various estimates and absorbing significantly in the range of 450 to 540 nm.
Melanopsin is a type of photopigment belonging to a larger family of light-sensitive retinal proteins called opsins and encoded by the gene Opn4. In the mammalian retina, there are two additional categories of opsins, both involved in the formation of visual images: rhodopsin and photopsin in the rod and cone photoreceptor cells, respectively.
Plymouth Marine Laboratory in the city of Plymouth, England, is a marine research organization and registered charity. It is a partner of the UK Research & Innovation's Natural Environment Research Council (NERC). PML's chair is Janice Timberlake, its chief executive is Prof. Icarus Allen and its patron is the film-maker James Cameron.
In developmental biology, photomorphogenesis is light-mediated development, where plant growth patterns respond to the light spectrum. This is a completely separate process from photosynthesis where light is used as a source of energy. Phytochromes, cryptochromes, and phototropins are photochromic sensory receptors that restrict the photomorphogenic effect of light to the UV-A, UV-B, blue, and red portions of the electromagnetic spectrum.
Phototropins are photoreceptor proteins that mediate phototropism responses in various species of algae, fungi and higher plants. Phototropins can be found throughout the leaves of a plant. Along with cryptochromes and phytochromes they allow plants to respond and alter their growth in response to the light environment. Phototropins may also be important for the opening of stomata and the movement of chloroplasts. These blue light receptors are seen across the entire green plant lineage. When Phototropins are hit with blue light, they induce a signal transduction pathway that alters the plant cells' functions in different ways.
Chromalveolata was a eukaryote supergroup present in a major classification of 2005, then regarded as one of the six major groups within the eukaryotes. It was a refinement of the kingdom Chromista, first proposed by Thomas Cavalier-Smith in 1981. Chromalveolata was proposed to represent the organisms descended from a single secondary endosymbiosis involving a red alga and a bikont. The plastids in these organisms are those that contain chlorophyll c.
In botany, a zoid or zoïd is a reproductive cell that possesses one or more flagella, and is capable of independent movement. Zoid can refer to either an asexually reproductive spore or a sexually reproductive gamete. In sexually reproductive gametes, zoids can be either male or female depending on the species. For example, some brown alga (Phaeophyceae) reproduce by producing multi-flagellated male and female gametes that recombine to form the diploid sporangia. Zoids are primarily found in some protists, diatoms, green alga, brown alga, non-vascular plants, and a few vascular plants. The most common classification group that produces zoids is the heterokonts or stramenopiles. These include green alga, brown alga, oomycetes, and some protists. The term is generally not used to describe motile, flagellated sperm found in animals. Zoid is also commonly confused for zooid which is a single organism that is part of a colonial animal.
The eyespot apparatus 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, or away from it. A related 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 phototactic response.
The SAR supergroup, also just SAR or Harosa, is a clade of eukaryotic organisms that includes stramenopiles (heterokonts), alveolates, and Rhizaria. The name is an acronym derived from the first letters of each of these clades; it has been alternatively spelled "RAS". The term "Harosa" has also been used. The SAR supergroup is a node-based taxon.
Phototropism is the growth of an organism in response to a light stimulus. Phototropism is most often observed in plants, but can also occur in other organisms such as fungi. The cells on the plant that are farthest from the light contain a hormone called auxin that reacts when phototropism occurs. This causes the plant to have elongated cells on the furthest side from the light. Phototropism is one of the many plant tropisms or movements which respond to external stimuli. Growth towards a light source is called positive phototropism, while growth away from light is called negative phototropism. Negative phototropism is not to be confused with skototropism which is defined as the growth towards darkness, whereas negative phototropism can refer to either the growth away from a light source or towards the darkness. Most plant shoots exhibit positive phototropism, and rearrange their chloroplasts in the leaves to maximize photosynthetic energy and promote growth. Some vine shoot tips exhibit negative phototropism, which allows them to grow towards dark, solid objects and climb them. The combination of phototropism and gravitropism allow plants to grow in the correct direction.
A Light-oxygen-voltage-sensing domain is a protein sensor used by a large variety of higher plants, microalgae, fungi and bacteria to sense environmental conditions. In higher plants, they are used to control phototropism, chloroplast relocation, and stomatal opening, whereas in fungal organisms, they are used for adjusting the circadian temporal organization of the cells to the daily and seasonal periods. They are a subset of PAS domains.
5-Fluoroorotic acid (5FOA) is a fluorinated derivative of the pyrimidine precursor orotic acid. It is used in yeast genetics to select for the absence of the URA3 gene, which encodes the enzyme for the decarboxylation of 5-fluoroorotic acid to 5-fluorouracil, a toxic metabolite. It has also been used in diatom selection.
John 'Keith' Moffat is Louis Block Professor of Biochemistry and Molecular Biology and former Deputy Provost for Research at the University of Chicago. He currently heads BioCARS at Argonne National Laboratory, where he worked on the Advanced Photon Source. He is most noted for his contributions to Time resolved crystallography. He is a former Guggenheim Fellow and former Cornell University faculty member. He has a Ph.D. from King's College, Cambridge under the Nobel laureate Max Perutz at MRC-LMB and an undergraduate degree from the University of Edinburgh. He is married with an adopted son.
Marine protists are defined by their habitat as protists that live in marine environments, that is, in the saltwater of seas or oceans or the brackish water of coastal estuaries. Life originated as marine single-celled prokaryotes and later evolved into more complex eukaryotes. Eukaryotes are the more developed life forms known as plants, animals, fungi and protists. Protists are the eukaryotes that cannot be classified as plants, fungi or animals. They are mostly single-celled and microscopic. The term protist came into use historically as a term of convenience for eukaryotes that cannot be strictly classified as plants, animals or fungi. They are not a part of modern cladistics because they are paraphyletic.
2-Fluoroadenine (2-FA) is a toxic adenine antimetabolite which can be used in laboratory biological research for counterselection of wildtype bacterial or eukaryotic APT genes. Therefore, knockouts or mutants for APT, which are resistant to 2-FA, can be selected.
References
- ↑ Takahashi, Fumio; Yamagata, Daisuke; Ishikawa, Mié; Fukamatsu, Yosuke; Ogura, Yasunobu; Kasahara, Masahiro; Kiyosue, Tomohiro; Kikuyama, Munehiro; Wada, Masamitsu (2007-12-04). "AUREOCHROME, a photoreceptor required for photomorphogenesis in stramenopiles". Proceedings of the National Academy of Sciences. 104 (49): 19625–19630. doi:10.1073/pnas.0707692104. PMC 2148339 . PMID 18003911.
- ↑ Kataoka, Hironao; Wada, Masamitsu; Kikuyama, Munehiro; Kiyosue, Tomohiro; Kasahara, Masahiro; Ogura, Yasunobu; Fukamatsu, Yosuke; Ishikawa, Mié; Yamagata, Daisuke (2007-12-04). "AUREOCHROME, a photoreceptor required for photomorphogenesis in stramenopiles". Proceedings of the National Academy of Sciences. PNAS, National Academy of Sciences. 104 (49): 19625–19630. doi:10.1073/pnas.0707692104. PMC 2148339 . PMID 18003911.
- ↑ Kroth, Peter G.; Wilhelm, Christian; Kottke, Tilman (2017). "An update on aureochromes: Phylogeny – mechanism – function". Journal of Plant Physiology. 217: 20–26. doi:10.1016/j.jplph.2017.06.010. PMID 28797596.
- ↑ Banerjee, Ankan; Herman, Elena; Serif, Manuel; Maestre-Reyna, Manuel; Hepp, Sebastian; Pokorny, Richard; Kroth, Peter G.; Essen, Lars-Oliver; Kottke, Tilman (2016). "Allosteric communication between DNA-binding and light-responsive domains of diatom class I aureochromes". Nucleic Acids Research. 44 (12): 5957–5970. doi:10.1093/nar/gkw420. PMC 4937327 . PMID 27179025.
- ↑ Serif, M.; Lepetit, B.; Weißert, K.; Kroth, P.G.; Rio Bartulos, C. (2017). "A fast and reliable strategy to generate TALEN-mediated gene knockouts in the diatom Phaeodactylum tricornutum" (PDF). Algal Research. 23: 186–195. doi:10.1016/j.algal.2017.02.005.
- ↑ Madhuri, S.; Río Bártulos, C.; Serif, M.; Lepetit, B.; Kroth, P.G. (2019). "A strategy to complement PtAUREO1a in TALEN knockout strains of Phaeodactylum tricornutum". Algal Research. 39: 101469. doi:10.1016/j.algal.2019.101469.