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Piwi-interacting RNA
Piwi-interacting RNA (piRNA) is the largest class of small non-coding RNA, non-coding RNA molecules expressed in animal cells. piRNAs form RNA-protein complexes through interactions with piwi-subfamily Argonaute proteins. These piRNA complexes are mostly involved in the Epigenetics, epigenetic and post-transcriptional modification, post-transcriptional silencing of transposable elements and other spurious or repeat-derived transcripts, but can also be involved in the regulation of other genetic elements in germ line cells. piRNAs are mostly created from loci that function as transposon traps which provide a kind of RNA-mediated adaptive immunity against transposon expansions and invasions. They are distinct from microRNA (miRNA) in size (26–31 nucleotides as opposed to 21–24 nt), lack of sequence conservation, increased complexity, and independence of Dicer for biogenesis, at least in animals. (Plant DCL1, Dcl2 may play a role in rasi/piRNA biogenesis.) Double-stranded RNAs ca ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Non-coding RNA
A non-coding RNA (ncRNA) is a functional RNA molecule that is not Translation (genetics), translated into a protein. The DNA sequence from which a functional non-coding RNA is transcribed is often called an RNA gene. Abundant and functionally important list of RNAs, types of non-coding RNAs include transfer RNAs (tRNAs) and ribosomal RNAs (rRNAs), as well as small RNAs such as microRNAs, siRNAs, piRNAs, snoRNAs, snRNAs, Extracellular RNA, exRNAs, scaRNAs and the long noncoding RNA, long ncRNAs such as Xist and HOTAIR. The number of non-coding RNAs within the human genome is unknown; however, recent Transcriptomics, transcriptomic and Bioinformatics, bioinformatic studies suggest that there are thousands of non-coding transcripts. Many of the newly identified ncRNAs have unknown functions, if any. There is no consensus on how much of non-coding transcription is functional: some believe most ncRNAs to be non-functional "junk RNA", spurious transcriptions, while others expect that ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
SiRNA
Small interfering RNA (siRNA), sometimes known as short interfering RNA or silencing RNA, is a class of double-stranded non-coding RNA molecules, typically 20–24 base pairs in length, similar to microRNA (miRNA), and operating within the RNA interference (RNAi) pathway. It interferes with the expression of specific genes with complementary nucleotide sequences by degrading messenger RNA (mRNA) after transcription, preventing translation. Text was copied from this source, which is available under Creative Commons Attribution 4.0 International License It was discovered in 1998 by Andrew Fire at the Carnegie Institution for Science in Washington, D.C. and Craig Mello at the University of Massachusetts in Worcester. Structure Naturally occurring siRNAs have a well-defined structure that is a short (usually 20 to 24- bp) double-stranded RNA (dsRNA) with phosphorylated 5' ends and hydroxylated 3' ends with two overhanging nucleotides. The Dicer enzyme catalyzes prod ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mammal
A mammal () is a vertebrate animal of the Class (biology), class Mammalia (). Mammals are characterised by the presence of milk-producing mammary glands for feeding their young, a broad neocortex region of the brain, fur or hair, and three Evolution of mammalian auditory ossicles, middle ear bones. These characteristics distinguish them from reptiles and birds, from which their ancestors Genetic divergence, diverged in the Carboniferous Period over 300 million years ago. Around 6,640 Neontology#Extant taxon, extant species of mammals have been described and divided into 27 Order (biology), orders. The study of mammals is called mammalogy. The largest orders of mammals, by number of species, are the rodents, bats, and eulipotyphlans (including hedgehogs, Mole (animal), moles and shrews). The next three are the primates (including humans, monkeys and lemurs), the Artiodactyl, even-toed ungulates (including pigs, camels, and whales), and the Carnivora (including Felidae, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mice
A mouse (: mice) is a small rodent. Characteristically, mice are known to have a pointed snout, small rounded ears, a body-length scaly tail, and a high breeding rate. The best known mouse species is the common house mouse (''Mus musculus''). Mice are also popular as pets. In some places, certain kinds of field mice are locally common. They are known to invade homes for food and shelter. Mice are typically distinguished from rats by their size. Generally, when a muroid rodent is discovered, its common name includes the term ''mouse'' if it is smaller, or ''rat'' if it is larger. The common terms ''rat'' and ''mouse'' are not taxonomically specific. Typical mice are classified in the genus '' Mus'', but the term ''mouse'' is not confined to members of ''Mus'' and can also apply to species from other genera such as the deer mouse (''Peromyscus''). Domestic mice sold as pets often differ substantially in size from the common house mouse. This is attributable to breedin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zebrafish
The zebrafish (''Danio rerio'') is a species of freshwater ray-finned fish belonging to the family Danionidae of the order Cypriniformes. Native to South Asia, it is a popular aquarium fish, frequently sold under the trade name zebra danio (and thus often called a " tropical fish" although it is both tropical and subtropical). The zebrafish is an important and widely used vertebrate model organism in scientific research, particularly developmental biology, but also gene function, oncology, teratology, and drug development, in particular pre-clinical development. It is also notable for its regenerative abilities, and has been modified by researchers to produce many transgenic strains. Taxonomy The zebrafish is a derived member of the genus '' Brachydanio'', of the family Cyprinidae. It has a sister-group relationship with '' Danio aesculapii''. Zebrafish are also closely related to the genus '' Devario'', as demonstrated by a phylogenetic tree of close species. Distri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Drosophila Melanogaster
''Drosophila melanogaster'' is a species of fly (an insect of the Order (biology), order Diptera) in the family Drosophilidae. The species is often referred to as the fruit fly or lesser fruit fly, or less commonly the "vinegar fly", "pomace fly", or "banana fly". In the wild, ''D. melanogaster'' are attracted to rotting fruit and fermenting beverages, and are often found in orchards, kitchens and pubs. Starting with Charles W. Woodworth's 1901 proposal of the use of this species as a model organism, ''D. melanogaster'' continues to be widely used for biological research in genetics, physiology, microbial pathogenesis, and Life history theory, life history evolution. ''D. melanogaster'' was the first animal to be Fruit flies in space, launched into space in 1947. As of 2017, six Nobel Prizes have been awarded to drosophilists for their work using the insect. ''Drosophila melanogaster'' is typically used in research owing to its rapid life cycle, relatively simple genetics with on ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Caenorhabditis Elegans
''Caenorhabditis elegans'' () is a free-living transparent nematode about 1 mm in length that lives in temperate soil environments. It is the type species of its genus. The name is a Hybrid word, blend of the Greek ''caeno-'' (recent), ''rhabditis'' (rod-like) and Latin ''elegans'' (elegant). In 1900, Émile Maupas, Maupas initially named it ''Rhabditidae, Rhabditides elegans.'' Günther Osche, Osche placed it in the subgenus ''Caenorhabditis'' in 1952, and in 1955, Ellsworth Dougherty, Dougherty raised ''Caenorhabditis'' to the status of genus. ''C. elegans'' is an unsegmented pseudocoelomate and lacks respiratory or circulatory systems. Most of these nematodes are hermaphrodites and a few are males. Males have specialised tails for mating that include spicule (nematode), spicules. In 1963, Sydney Brenner proposed research into ''C. elegans,'' primarily in the area of neuronal development. In 1974, he began research into the molecular biology, molecular and developmental ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Uridine
Uridine (symbol U or Urd) is a glycosylated pyrimidine analog containing uracil attached to a ribose ring (or more specifically, a ribofuranose) via a β-N1- glycosidic bond. The analog is one of the five standard nucleosides which make up nucleic acids, the others being adenosine, thymidine, cytidine and guanosine. The five nucleosides are commonly abbreviated to their symbols, U, A, dT, C, and G, respectively. However, thymidine is more commonly written as 'dT' ('d' represents 'deoxy') as it contains a 2'-deoxyribofuranose moiety rather than the ribofuranose ring found in uridine. This is because thymidine is found in deoxyribonucleic acid (DNA) and usually not in ribonucleic acid (RNA). Conversely, uridine is found in RNA and not DNA. The remaining three nucleosides may be found in both RNA and DNA. In RNA, they would be represented as A, C and G whereas in DNA they would be represented as dA, dC and dG. Biosynthesis Uridine is widely produced in nature as uridine mon ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Directionality (molecular Biology)
Directionality, in molecular biology and biochemistry, is the end-to-end chemical orientation of a single strand of nucleic acid. In a single strand of DNA or RNA, the chemical convention of naming carbon atoms in the nucleotide Pentose, pentose-sugar-ring means that there will be a 5′ end (usually pronounced "five-prime end"), which frequently contains a phosphate group attached to the 5′ carbon of the ribose ring, and a 3′ end (usually pronounced "three-prime end"), which typically is unmodified from the ribose -OH substituent. In a DNA double helix, the strands run in opposite directions to permit base pairing between them, which is essential for replication or Transcription (biology), transcription of the encoded information. Nucleic acids can only be synthesized in vivo in the 5′-to-3′ direction, as the polymerases that assemble various types of new strands generally rely on the energy produced by breaking nucleoside triphosphate bonds to attach new nucleo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nucleotide
Nucleotides are Organic compound, organic molecules composed of a nitrogenous base, a pentose sugar and a phosphate. They serve as monomeric units of the nucleic acid polymers – deoxyribonucleic acid (DNA) and ribonucleic acid (RNA), both of which are essential biomolecules within all Life, life-forms on Earth. Nucleotides are obtained in the diet and are also synthesized from common Nutrient, nutrients by the liver. Nucleotides are composed of three subunit molecules: a nucleobase, a pentose, five-carbon sugar (ribose or deoxyribose), and a phosphate group consisting of one to three phosphates. The four nucleobases in DNA are guanine, adenine, cytosine, and thymine; in RNA, uracil is used in place of thymine. Nucleotides also play a central role in metabolism at a fundamental, cellular level. They provide chemical energy—in the form of the nucleoside triphosphates, adenosine triphosphate (ATP), guanosine triphosphate (GTP), cytidine triphosphate (CTP), and uridine triph ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Secondary Structure
Protein secondary structure is the local spatial conformation of the polypeptide backbone excluding the side chains. The two most common Protein structure#Secondary structure, secondary structural elements are alpha helix, alpha helices and beta sheets, though beta turns and omega loops occur as well. Secondary structure elements typically spontaneously form as an intermediate before the protein protein folding, folds into its three dimensional protein tertiary structure, tertiary structure. Secondary structure is formally defined by the pattern of hydrogen bonds between the Amine, amino hydrogen and carboxyl oxygen atoms in the peptide backbone chain, backbone. Secondary structure may alternatively be defined based on the regular pattern of backbone Dihedral angle#Dihedral angles of proteins, dihedral angles in a particular region of the Ramachandran plot regardless of whether it has the correct hydrogen bonds. The concept of secondary structure was first introduced by Kaj Ulrik ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Biogenesis
Spontaneous generation is a Superseded scientific theories, superseded scientific theory that held that living creatures could arise from abiotic component, non-living matter and that such processes were commonplace and regular. It was Hypothesis, hypothesized that certain forms, such as fleas, could arise from inanimate matter such as dust, or that maggots could arise from dead flesh. The doctrine of spontaneous generation was coherently synthesized by the Greek philosopher and naturalist Aristotle, who compiled and expanded the work of Pre-Socratic philosophy, earlier natural philosophers and the various ancient explanations for the appearance of organisms. Spontaneous generation was taken as scientific fact for two millennia. Though challenged in the 17th and 18th centuries by the experiments of the Italian biologists Francesco Redi and Lazzaro Spallanzani, it was not discredited until the work of the French chemist Louis Pasteur and the Irish physicist John Tyndall in the m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
