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Onion Test
The onion test is a way of assessing the validity of an argument for a functional role for junk DNA. It relates to the paradox that would emerge if the majority of eukaryotic non-coding DNA were assumed to be functional and the difficulty of reconciling that assumption with the diversity in genome sizes among species. The term "onion test" was originally proposed informally in a blog post by T. Ryan Gregory in order to help clarify the debate about junk DNA. The term has been mentioned in newspapers and online media, scientific journal articles, and a textbook. The test is defined as: The onion test is a simple reality check for anyone who thinks they have come up with a universal function for junk DNA. Whatever your proposed function, ask yourself this question: Can I explain why an onion needs about five times more non-coding DNA for this function than a human?Onions and their relatives vary dramatically in their genome sizes, without changing their ploidy, and this gives an excepti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Junk DNA
Non-coding DNA (ncDNA) sequences are components of an organism's DNA that do not genetic code, encode protein sequences. Some non-coding DNA is Transcription (genetics), transcribed into functional non-coding RNA molecules (e.g. transfer RNA, microRNA, Piwi-interacting RNA, piRNA, ribosomal RNA, and RNA interference, regulatory RNAs). Other functional regions of the non-coding DNA fraction include regulatory sequences that control gene expression; scaffold attachment regions; origin of replication, origins of DNA replication; centromeres; and telomeres. Some non-coding regions appear to be mostly nonfunctional such as introns, pseudogenes, intergenic DNA, and fragments of transposons and viruses. Fraction of non-coding genomic DNA In bacteria, the coding regions typically take up 88 % of the genome. The remaining 12 % consists largely of non-coding genes and regulatory sequences, which means that almost all of the bacterial genome has a function. The amount of coding DNA ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Allium Ursinum
''Allium ursinum'', known as wild garlic, ramsons, cowleekes, cows's leek, cowleek, buckrams, broad-leaved garlic, wood garlic, bear leek, Eurasian wild garlic or bear's garlic, is a bulbous perennial flowering plant in the amaryllis family Amaryllidaceae. It is native to Europe and Asia, where it grows in moist woodland. It is a wild relative of onion and garlic, all belonging to the same genus, ''Allium''. There are two recognized subspecies: ''A. ursinum'' subsp. ''ursinum'' and ''A. ursinum'' subsp. ''ucrainicum''. Etymology The Latin specific name ''ursinum'' translates to 'bear' and refers to the supposed fondness of the brown bear for the bulbs; folk tales describe the bears consuming them after awakening from hibernation. Another theory is that the "''ursinum''" may refer to Ursa Major, as ''A. ursinum'' was perhaps one of the most northerly distributed ''Allium'' species known to the ancient Greeks, though this hypothesis is disputed. Common names for th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
John Mattick
John Stanley Mattick (born 1950, Sydney) is an Australian molecular biologist known for his efforts to assign function to non-coding DNA. Mattick was the executive director of the Garvan Institute of Medical Research from 2012 to 2018. He joined Genomics England in May 2018 as Chief Executive Officer. In October 2019, he joined the University of New South Wales in Sydney. Career Mattick received his high school education at St Patrick's College Strathfield. He obtained his Bachelor of Science from the University of Sydney and his PhD in biochemistry from Monash University. Subsequently, he worked at Baylor College of Medicine in Houston, the CSIRO Division of Molecular Biology in Sydney, and the University of Queensland, where he was based between 1988 and 2012. Mattick has also worked at the Universities of Cambridge, Oxford, Cologne and Strasbourg. He was Foundation Director of the Australian Genome Research Facility, two ARC Special Research Centres and the Institute fo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polyploidy
Polyploidy is a condition in which the cells of an organism have more than one pair of ( homologous) chromosomes. Most species whose cells have nuclei ( eukaryotes) are diploid, meaning they have two sets of chromosomes, where each set contains one or more chromosomes and comes from each of two parents, resulting in pairs of homologous chromosomes between sets. However, some organisms are polyploid. Polyploidy is especially common in plants. Most eukaryotes have diploid somatic cells, but produce haploid gametes (eggs and sperm) by meiosis. A monoploid has only one set of chromosomes, and the term is usually only applied to cells or organisms that are normally diploid. Males of bees and other Hymenoptera, for example, are monoploid. Unlike animals, plants and multicellular algae have life cycles with two alternating multicellular generations. The gametophyte generation is haploid, and produces gametes by mitosis, the sporophyte generation is diploid and produces spores by mei ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ewan Birney
John Frederick William Birney (known as Ewan Birney) (born 6 December 1972) is joint director of EMBL's European Bioinformatics Institute (EMBL-EBI), in Hinxton, Cambridgeshire and deputy director general of the European Molecular Biology Laboratory (EMBL). He also serves as non-executive director of Genomics England, chair of the Global Alliance for Genomics and Health (GA4GH) and honorary professor of bioinformatics at the University of Cambridge. Birney has made significant contributions to genomics, through his development of innovative bioinformatics and computational biology tools. He previously served as an associate faculty member at the Wellcome Trust Sanger Institute. Education Birney was educated at Eton College as an Oppidan Scholar. Before going to university, Birney completed a gap year internship at Cold Spring Harbor Laboratory supervised by James Watson and Adrian Krainer. Birney completed his Bachelor of Arts degree in Biochemistry at the University of Oxfor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Selective Advantage
In biology, adaptation has three related meanings. Firstly, it is the dynamic evolutionary process of natural selection that fits organisms to their environment, enhancing their evolutionary fitness. Secondly, it is a state reached by the population during that process. Thirdly, it is a phenotypic trait or adaptive trait, with a functional role in each individual organism, that is maintained and has evolved through natural selection. Historically, adaptation has been described from the time of the ancient Greek philosophers such as Empedocles and Aristotle. In 18th and 19th century natural theology, adaptation was taken as evidence for the existence of a deity. Charles Darwin proposed instead that it was explained by natural selection. Adaptation is related to biological fitness, which governs the rate of evolution as measured by change in allele frequencies. Often, two or more species co-adapt and co-evolve as they develop adaptations that interlock with those of the other ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Protozoa
Protozoa (singular: protozoan or protozoon; alternative plural: protozoans) are a group of single-celled eukaryotes, either free-living or parasitic, that feed on organic matter such as other microorganisms or organic tissues and debris. Historically, protozoans were regarded as "one-celled animals", because they often possess animal-like behaviours, such as motility and predation, and lack a cell wall, as found in plants and many algae. When first introduced by Georg Goldfuss (originally spelled Goldfuß) in 1818, the taxon Protozoa was erected as a class within the Animalia, with the word 'protozoa' meaning "first animals". In later classification schemes it was elevated to a variety of higher ranks, including phylum, subkingdom and kingdom, and sometimes included within Protoctista or Protista. The approach of classifying Protozoa within the context of Animalia was widespread in the 19th and early 20th century, but not universal. By the 1970s, it became usual to require th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
C-value
C-value is the amount, in picograms, of DNA contained within a haploid nucleus (e.g. a gamete) or one half the amount in a diploid somatic cell of a eukaryotic organism. In some cases (notably among diploid organisms), the terms C-value and genome size are used interchangeably; however, in polyploids the C-value may represent two or more genomes contained within the same nucleus. Greilhuber ''et al.'' have suggested some new layers of terminology and associated abbreviations to clarify this issue, but these somewhat complex additions are yet to be used by other authors. Origin of the term Many authors have incorrectly assumed that the 'C' in "C-value" refers to "characteristic", "content", or "complement". Even among authors who have attempted to trace the origin of the term, there had been some confusion because Hewson Swift did not define it explicitly when he coined it in 1950. In his original paper, Swift appeared to use the designation "1C value", "2C value", etc., in re ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chives
Chives, scientific name ''Allium schoenoprasum'', is a species of flowering plant in the family Amaryllidaceae that produces edible leaves and flowers. Their close relatives include the common onions, garlic, shallot, leek, scallion, and Chinese onion. A perennial plant, it is widespread in nature across much of Europe, Asia, and North America. ''A. schoenoprasum'' is the only species of ''Allium'' native to both the New and the Old Worlds.Ernest Small James Cullen, Sabina G. Knees, H. Suzanne Cubey (Editors) Chives are a commonly used herb and can be found in grocery stores or grown in home gardens. In culinary use, the green stalks ( scapes) and the unopened, immature flower buds are diced and used as an ingredient for omelettes, fish, potatoes, soups, and many other dishes. The edible flowers can be used in salads. Chives have insect-repelling properties that can be used in gardens to control pests. The plant provides a great deal of nectar for pollinators. It ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eukaryotic
Eukaryotes () are organisms whose cells have a nucleus. All animals, plants, fungi, and many unicellular organisms, are Eukaryotes. They belong to the group of organisms Eukaryota or Eukarya, which is one of the three domains of life. Bacteria and Archaea (both prokaryotes) make up the other two domains. The eukaryotes are usually now regarded as having emerged in the Archaea or as a sister of the Asgard archaea. This implies that there are only two domains of life, Bacteria and Archaea, with eukaryotes incorporated among archaea. Eukaryotes represent a small minority of the number of organisms, but, due to their generally much larger size, their collective global biomass is estimated to be about equal to that of prokaryotes. Eukaryotes emerged approximately 2.3–1.8 billion years ago, during the Proterozoic eon, likely as flagellated phagotrophs. Their name comes from the Greek εὖ (''eu'', "well" or "good") and κάρυον (''karyon'', "nut" or "kernel"). Euka ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ploidy
Ploidy () is the number of complete sets of chromosomes in a cell (biology), cell, and hence the number of possible alleles for Autosome, autosomal and Pseudoautosomal region, pseudoautosomal genes. Sets of chromosomes refer to the number of maternal and paternal chromosome copies, respectively, in each homologous chromosome pair, which chromosomes naturally exist as. Somatic cells, Tissue (biology), tissues, and Individual#Biology, individual organisms can be described according to the number of sets of chromosomes present (the "ploidy level"): monoploid (1 set), diploid (2 sets), triploid (3 sets), tetraploid (4 sets), pentaploid (5 sets), hexaploid (6 sets), heptaploid or septaploid (7 sets), etc. The generic term polyploidy, polyploid is often used to describe cells with three or more chromosome sets. Virtually all sexual reproduction, sexually reproducing organisms are made up of somatic cells that are diploid or greater, but ploidy level may vary widely between different or ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Human Genome
The human genome is a complete set of nucleic acid sequences for humans, encoded as DNA within the 23 chromosome pairs in cell nuclei and in a small DNA molecule found within individual mitochondria. These are usually treated separately as the nuclear genome and the mitochondrial genome. Human genomes include both protein-coding DNA sequences and various types of DNA that does not encode proteins. The latter is a diverse category that includes DNA coding for non-translated RNA, such as that for ribosomal RNA, transfer RNA, ribozymes, small nuclear RNAs, and several types of regulatory RNAs. It also includes promoters and their associated gene-regulatory elements, DNA playing structural and replicatory roles, such as scaffolding regions, telomeres, centromeres, and origins of replication, plus large numbers of transposable elements, inserted viral DNA, non-functional pseudogenes and simple, highly-repetitive sequences. Introns make up a large percentage of non-coding DNA. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
