1.
Chromosome
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A chromosome is a DNA molecule with part or all of the genetic material of an organism. Prokaryotes usually have one single circular chromosome, whereas most eukaryotes are diploid, chromosomes in eukaryotes are composed of chromatin fiber. Chromatin fiber is made of nucleosomes, a nucleosome is a histone octamer with part of a longer DNA strand attached to and wrapped around it. Chromatin fiber, together with associated proteins is known as chromatin, chromatin is present in most cells, with a few exceptions, for example, red blood cells. Occurring only in the nucleus of cells, chromatin contains the vast majority of DNA, except for a small amount inherited maternally. Chromosomes are normally visible under a microscope only when the cell is undergoing the metaphase of cell division. Before this happens every chromosome is copied once, and the copy is joined to the original by a centromere resulting in an X-shaped structure, the original chromosome and the copy are now called sister chromatids. During metaphase, when a chromosome is in its most condensed state, in this highly condensed form chromosomes are easiest to distinguish and study. In prokaryotic cells, chromatin occurs free-floating in cytoplasm, as these cells lack organelles, the main information-carrying macromolecule is a single piece of coiled double-helix DNA, containing many genes, regulatory elements and other noncoding DNA. The DNA-bound macromolecules are proteins that serve to package the DNA, chromosomes vary widely between different organisms. Some species such as certain bacteria also contain plasmids or other extrachromosomal DNA and these are circular structures in the cytoplasm that contain cellular DNA and play a role in horizontal gene transfer. Chromosomal recombination during meiosis and subsequent sexual reproduction plays a significant role in genetic diversity. In prokaryotes and viruses, the DNA is often densely packed and organized, in the case of archaea, by homologs to eukaryotic histones, small circular genomes called plasmids are often found in bacteria and also in mitochondria and chloroplasts, reflecting their bacterial origins. Some use the term chromosome in a sense, to refer to the individualized portions of chromatin in cells. However, others use the concept in a sense, to refer to the individualized portions of chromatin during cell division. The word chromosome comes from the Greek χρῶμα and σῶμα, describing their strong staining by particular dyes, schleiden, Virchow and Bütschli were among the first scientists who recognized the structures now so familiar to everyone as chromosomes. The term was coined by von Waldeyer-Hartz, referring to the term chromatin, in a series of experiments beginning in the mid-1880s, Theodor Boveri gave the definitive demonstration that chromosomes are the vectors of heredity. His two principles were the continuity of chromosomes and the individuality of chromosomes and it is the second of these principles that was so original
2.
Homology (biology)
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In biology, homology is the existence of shared ancestry between a pair of structures, or genes, in different taxa. Evolutionary biology explains homologous structures adapted to different purposes as the result of descent with modification from a common ancestor, examples include the legs of a centipede, the maxillary palp and labial palp of an insect, and the spinous processes of successive vertebrae in a vertebral column. Sequence homology between protein or DNA sequences is defined in terms of shared ancestry. Two segments of DNA can have shared ancestry because of either an event or a duplication event. Homology among proteins or DNA is inferred from their sequence similarity, significant similarity is strong evidence that two sequences are related by divergent evolution from a common ancestor. Alignments of multiple sequences are used to discover the homologous regions, the word homology, coined in about 1656, derives from the Greek ὁμόλογος homologos from ὁμός homos same and λόγος logos relation. Homology is the relationship between biological structures or sequences that are derived from a common ancestor, for example, many insects possess two pairs of flying wings. In beetles, the first pair of wings has evolved into a pair of hard wing covers, the same major forearm bones are found in fossils of lobe-finned fish such as Eusthenopteron. The opposite of homologous organs are analogous organs which do similar jobs in two taxa that were not present in their last common ancestor but rather evolved separately. For example, the wings of insects and birds evolved independently in widely separated groups, similarly, the wings of a sycamore maple seed and the wings of a bird are analogous but not homologous, as they develop from quite different structures. A structure can be homologous at one level, but only analogous at another, for example, in the pterosaurs, the wing involves both the forelimb and the hindlimb. Analogy is called homoplasy in cladistics, and convergent or parallel evolution in evolutionary biology, specialised terms are used in taxonomic research. Primary homology is that initially conjectured by a researcher based on similar structure or anatomical connections, secondary homology is implied by parsimony analysis, where a character that only occurs once on a tree is taken to be homologous. As implied in this definition, many cladists consider homology to be synonymous with synapomorphy, homologies provide the fundamental basis for all biological classification, although some may be highly counter-intuitive. The homologies between these have been discovered by comparing genes in evolutionary developmental biology, among insects, the stinger of the female honey bee is a modified ovipositor, homologous with ovipositors in other insects such as the Orthoptera, Hemiptera, and those Hymenoptera without stingers. The three small bones in the ear of mammals including humans, the malleus, incus. The malleus and incus develop in the embryo from structures that form jaw bones in lizards, both lines of evidence show that these bones are homologous, sharing a common ancestor. Among the many homologies in mammal reproductive systems, ovaries and testicles are homologous, in many plants, defensive or storage structures are made by modifications of the development of primary leaves, stems, and roots
3.
Placenta
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The placenta provides oxygen and nutrients to growing babies and removes waste products from the babys blood. The placenta attaches to the wall of the uterus, and the umbilical cord develops from the placenta. The umbilical cord is what connects the mother and the baby, Placentas are a defining characteristic of placental mammals, but are also found in some non-mammals with varying levels of development. The homology of structures in various viviparous organisms is debatable. The classical plural is placentae, but the form placentas is common in modern English, prototherial and metatherial mammals produce a choriovitelline placenta that, while connected to the uterine wall, provides nutrients mainly derived from the egg sac. In humans, the placenta averages 22 cm in length and 2–2.5 cm in thickness, with the center being the thickest, and it typically weighs approximately 500 grams. It has a dark reddish-blue or crimson color and it connects to the fetus by an umbilical cord of approximately 55–60 cm in length, which contains two umbilical arteries and one umbilical vein. The umbilical cord inserts into the chorionic plate, vessels branch out over the surface of the placenta and further divide to form a network covered by a thin layer of cells. This results in the formation of villous tree structures, on the maternal side, these villous tree structures are grouped into lobules called cotyledons. In humans, the placenta usually has a shape. The placental flora more closely resembles that of the oral microbiome than either the vaginal or rectal microbiome, in non-human animals, part of the microbiome is passed onto offspring even before the offspring are born. Bacteriologists assume that the same holds true for humans. The placenta begins to develop upon implantation of the blastocyst into the maternal endometrium, the outer layer of the blastocyst becomes the trophoblast, which forms the outer layer of the placenta. This outer layer is divided into two layers, the underlying cytotrophoblast layer and the overlying syncytiotrophoblast layer. The syncytiotrophoblast is a continuous cell layer that covers the surface of the placenta. It forms as a result of differentiation and fusion of the underlying cytotrophoblast cells, the syncytiotrophoblast, thereby contributes to the barrier function of the placenta. Development of the blood supply to the placenta is complete by the end of the first trimester of pregnancy. In preparation for implantation of the blastocyst, the uterine endometrium undergoes decidualisation, spiral arteries in decidua are remodeled so that they become less convoluted and their diameter is increased
4.
Birth
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Birth, also known as parturition, is the act or process of bearing or bringing forth offspring. In some species the offspring is precocial and can move around almost immediately after birth but in others it is altricial, in marsupials, the fetus is born at a very immature stage after a short gestational period and develops further in its mothers wombs pouch. It is not only humans and mammals give birth. Some reptiles, amphibians, fish and invertebrates carry their young inside them. Some of these are ovoviviparous, with the eggs being hatched inside the mothers body, in these large animals, the birth process is similar to that of a human, though in most the offspring is precocial. This means that it is born in an advanced state than a human baby and is able to stand, walk. In the case of whales, dolphins and porpoises, the calf is normally born tail first which minimises the risk of drowning. The mother encourages the newborn calf to rise to the surface of the water to breathe, most smaller mammals have multiple births, producing litters of young which may number twelve or more. In these animals, each fetus is surrounded by its own amniotic sac and has a separate placenta and this separates from the wall of the uterus during labor and the fetus works its way towards the birth canal. Humans usually produce a single offspring at a time, the mothers body is prepared for birth by hormones produced by the pituitary gland, the ovary and the placenta. The total gestation period from fertilization to birth is normally about 38 weeks, the normal process of childbirth takes several hours and has three stages. The first stage starts with a series of contractions of the muscular walls of the uterus. The active phase of the first stage starts when the cervix is dilated more than about 4 cm in diameter and is when the contractions become stronger, the head of the baby is pushed against the cervix, which gradually dilates until is fully dilated at 10 cm diameter. At some time, the sac bursts and the amniotic fluid escapes. In stage three, which begins after the birth of the baby, further contractions expel the placenta, amniotic sac, enormous changes take place in the newborns circulation to enable breathing in air. The umbilical vein, umbilical arteries, ductus venosus and ductus arteriosus are not needed for life in air, birthing in cattle is typical of a larger mammal. A cow goes through three stages of labor during normal delivery of a calf, during stage one, the animal seeks a quiet place away from the rest of the herd. Hormone changes cause soft tissues of the canal to relax as the mothers body prepares for birth
5.
Gene expression
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Gene expression is the process by which information from a gene is used in the synthesis of a functional gene product. These products are proteins, but in non-protein coding genes such as transfer RNA or small nuclear RNA genes. The process of gene expression is used by all known life—eukaryotes, prokaryotes, several steps in the gene expression process may be modulated, including the transcription, RNA splicing, translation, and post-translational modification of a protein. Gene regulation gives the cell control over structure and function, and is the basis for differentiation, morphogenesis. In genetics, gene expression is the most fundamental level at which the genotype gives rise to the phenotype, the genetic code stored in DNA is interpreted by gene expression, and the properties of the expression give rise to the organisms phenotype. Such phenotypes are expressed by the synthesis of proteins that control the organisms shape. Regulation of gene expression is critical to an organisms development. A gene is a stretch of DNA that encodes information, genomic DNA consists of two antiparallel and reverse complementary strands, each having 5 and 3 ends. This RNA is complementary to the template 3 →5 DNA strand, therefore, the resulting 5 →3 RNA strand is identical to the coding DNA strand with the exception that thymines are replaced with uracils in the RNA. A coding DNA strand reading ATG is indirectly transcribed through the non-coding strand as AUG in RNA, in prokaryotes, transcription is carried out by a single type of RNA polymerase, which needs a DNA sequence called a Pribnow box as well as a sigma factor to start transcription. RNA polymerase I is responsible for transcription of ribosomal RNA genes, RNA polymerase II transcribes all protein-coding genes but also some non-coding RNAs. Pol II includes a C-terminal domain that is rich in serine residues, when these residues are phosphorylated, the CTD binds to various protein factors that promote transcript maturation and modification. RNA polymerase III transcribes 5S rRNA, transfer RNA genes, transcription ends when the polymerase encounters a sequence called the terminator. These include 5 capping, which is set of reactions that add 7-methylguanosine to the 5 end of pre-mRNA. The m7G cap is then bound by cap binding complex heterodimer, another modification is 3 cleavage and polyadenylation. They occur if polyadenylation signal sequence is present in pre-mRNA, which is usually between protein-coding sequence and terminator, the pre-mRNA is first cleaved and then a series of ~200 adenines are added to form poly tail, which protects the RNA from degradation. Poly tail is bound by multiple poly-binding proteins necessary for mRNA export, a very important modification of eukaryotic pre-mRNA is RNA splicing. The majority of eukaryotic pre-mRNAs consist of alternating segments called exons and introns, in certain cases, some introns or exons can be either removed or retained in mature mRNA
6.
T cell
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A T cell, or T lymphocyte, is a type of lymphocyte that plays a central role in cell-mediated immunity. T cells can be distinguished from other lymphocytes, such as B cells and natural killer cells and they are called T cells because they mature in the thymus from thymocytes. The several subsets of T cells each have a distinct function, the majority of human T cells rearrange their alpha and beta chains on the cell receptor and are termed alpha beta T cells and are part of the adaptive immune system. The category of effector T cell is a one that includes various T cell types that actively respond to a stimulus. This includes helper, killer, regulatory, and potentially other T cell types, T helper cells assist other white blood cells in immunologic processes, including maturation of B cells into plasma cells and memory B cells, and activation of cytotoxic T cells and macrophages. These cells are known as CD4+ T cells because they express the CD4 glycoprotein on their surfaces. Helper T cells become activated when they are presented with peptide antigens by MHC class II molecules, once activated, they divide rapidly and secrete small proteins called cytokines that regulate or assist in the active immune response. These cells can differentiate one of several subtypes, including TH1, TH2, TH3, TH17, TH9, or TFH. Signalling from the APC directs T cells into particular subtypes, cytotoxic T cells destroy virus-infected cells and tumor cells, and are also implicated in transplant rejection. These cells are known as CD8+ T cells since they express the CD8 glycoprotein at their surfaces. These cells recognize their targets by binding to antigen associated with MHC class I molecules, through IL-10, adenosine, and other molecules secreted by regulatory T cells, the CD8+ cells can be inactivated to an anergic state, which prevents autoimmune diseases. Appropriate co-stimulation must be present at the time of encounter for this process to occur. Historically, memory T cells were thought to belong to either the effector or central memory subtypes, subsequently, numerous new populations of memory T cells were discovered including tissue-resident memory T cells, stem memory TSCM cells, and virtual memory T cells. The single unifying theme for all memory T cell subtypes is that they are long-lived, by this mechanism they provide the immune system with memory against previously encountered pathogens. Memory T cells may be either CD4+ or CD8+ and usually express CD45RO, memory T cell subtypes, Central memory T cells express CD45RO, C-C chemokine receptor type 7, and L-selectin. Central memory T cells also have intermediate to high expression of CD44 and this memory subpopulation is commonly found in the lymph nodes and in the peripheral circulation. Effector memory T cells express CD45RO but lack expression of CCR7 and they also have intermediate to high expression of CD44. These memory T cells lack lymph node-homing receptors and are found in the peripheral circulation
7.
Gene
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A gene is a locus of DNA which is made up of nucleotides and is the molecular unit of heredity. The transmission of genes to an offspring is the basis of the inheritance of phenotypic traits. These genes make up different DNA sequences called genotypes, genotypes along with environmental and developmental factors determine what the phenotypes will be. Most biological traits are under the influence of polygenes as well as gene–environment interactions, genes can acquire mutations in their sequence, leading to different variants, known as alleles, in the population. These alleles encode slightly different versions of a protein, which cause different phenotypical traits, usage of the term having a gene typically refers to containing a different allele of the same, shared gene. Genes evolve due to natural selection or survival of the fittest of the alleles, the concept of a gene continues to be refined as new phenomena are discovered. For example, regulatory regions of a gene can be far removed from its coding regions, some viruses store their genome in RNA instead of DNA and some gene products are functional non-coding RNAs. The existence of discrete inheritable units was first suggested by Gregor Mendel, from 1857 to 1864, in Brno, he studied inheritance patterns in 8000 common edible pea plants, tracking distinct traits from parent to offspring. He described these mathematically as 2n combinations where n is the number of differing characteristics in the original peas, although he did not use the term gene, he explained his results in terms of discrete inherited units that give rise to observable physical characteristics. This description prefigured the distinction between genotype and phenotype, charles Darwin developed a theory of inheritance he termed pangenesis, from Greek pan and genesis / genos. Darwin used the term gemmule to describe hypothetical particles that would mix during reproduction, de Vries called these units pangenes, after Darwins 1868 pangenesis theory. In 1909 the Danish botanist Wilhelm Johannsen shortened the name to gene, advances in understanding genes and inheritance continued throughout the 20th century. Deoxyribonucleic acid was shown to be the repository of genetic information by experiments in the 1940s to 1950s. In the early 1950s the prevailing view was that the genes in a chromosome acted like discrete entities, indivisible by recombination, collectively, this body of research established the central dogma of molecular biology, which states that proteins are translated from RNA, which is transcribed from DNA. This dogma has since shown to have exceptions, such as reverse transcription in retroviruses. The modern study of genetics at the level of DNA is known as molecular genetics, in 1972, Walter Fiers and his team at the University of Ghent were the first to determine the sequence of a gene, the gene for Bacteriophage MS2 coat protein. The subsequent development of chain-termination DNA sequencing in 1977 by Frederick Sanger improved the efficiency of sequencing, an automated version of the Sanger method was used in early phases of the Human Genome Project. The theories developed in the 1930s and 1940s to integrate molecular genetics with Darwinian evolution are called the evolutionary synthesis
8.
Beta-Endorphin
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β-Endorphin is an endogenous opioid neuropeptide found in the neurons of both the central and peripheral nervous system. It is one of five endorphins found in humans, the others of which include α-endorphin, γ-endorphin, α-neoendorphin, the amino acid sequence is, Tyr-Gly-Gly-Phe-Met-Thr-Ser-Glu-Lys-Ser-Gln-Thr-Pro-Leu-Val-Thr-Leu-Phe-Lys-Asn-Ala-Ile-Ile-Lys-Asn-Ala-Tyr-Lys-Lys-Gly-Glu. The first 16 amino acids are identical to α-Endorphin, β-Endorphin is a peptide,31 amino acids long, resulting from processing of the precursor proopiomelanocortin. β-Endorphin is found in neurons of the hypothalamus, as well as the pituitary gland, β-Endorphin was discovered in camel pituitary extracts by C. H. It is used as an analgesic in the body to numb or dull pains and that is the reason why humans start to feel better immediately after an acute physical trauma even though the symptoms are still present. The reason the pain dulls is because it binds to and activates opioid receptors, β-Endorphin has approximately 18 to 33 times the analgesic potency of morphine, though its hormonal effect is species dependent. β-Endorphin release in response to exercise has been known and studied since at least the 1980s, studies have demonstrated that serum concentrations of endogenous opioids, in particular β-endorphin and β-lipotrophin, increase in response to both acute exercise and training. The release of β-endorphin during exercise is associated with a phenomenon known in popular culture as a runners high. CID16132316 from PubChem - β-endorphin CID3081525 from PubChem - β-endorphin CID133304 from PubChem - β-endorphin β-endorphin at the US National Library of Medicine Medical Subject Headings
9.
Recombinant DNA
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Recombinant DNA is possible because DNA molecules from all organisms share the same chemical structure. They differ only in the sequence within that identical overall structure. Recombinant DNA is the name for a piece of DNA that has been created by the combination of at least two strands. Recombinant DNA molecules are called chimeric DNA, because they can be made of material from two different species, like the mythical chimera. R-DNA technology uses palindromic sequences and leads to the production of sticky, the DNA sequences used in the construction of recombinant DNA molecules can originate from any species. For example, plant DNA may be joined to bacterial DNA, in addition, DNA sequences that do not occur anywhere in nature may be created by the chemical synthesis of DNA, and incorporated into recombinant molecules. Using recombinant DNA technology and synthetic DNA, literally any DNA sequence may be created and introduced into any of a wide range of living organisms. Proteins that can result from the expression of recombinant DNA within living cells are termed recombinant proteins, when recombinant DNA encoding a protein is introduced into a host organism, the recombinant protein is not necessarily produced. Expression of foreign proteins requires the use of specialized expression vectors, molecular cloning is the laboratory process used to create recombinant DNA. It is one of two widely used methods, along with polymerase chain reaction, used to direct the replication of any specific DNA sequence chosen by the experimentalist, there are two fundamental differences between the methods. One is that cloning involves replication of the DNA within a living cell, while PCR replicates DNA in the test tube. The other difference is that cloning involves cutting and pasting DNA sequences, formation of recombinant DNA requires a cloning vector, a DNA molecule that replicates within a living cell. The choice of vector for molecular cloning depends on the choice of host organism, the size of the DNA to be cloned, the DNA segments can be combined by using a variety of methods, such as restriction enzyme/ligase cloning or Gibson assembly. These steps are described in detail in a related article. Following transplantation into the host organism, the foreign DNA contained within the recombinant DNA construct may or may not be expressed and that is, the DNA may simply be replicated without expression, or it may be transcribed and translated and a recombinant protein is produced. Specific changes to the host organism may be made to improve expression of the ectopic gene, in most cases, organisms containing recombinant DNA have apparently normal phenotypes. Significant exceptions exist, and are discussed below, gross phenotypic changes are not the norm, unless the recombinant gene has been chosen and modified so as to generate biological activity in the host organism. In some cases, recombinant DNA can have deleterious effects even if it is not expressed, one mechanism by which this happens is insertional inactivation, in which the rDNA becomes inserted into a host cells gene
10.
Stress (biology)
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Physiological or biological stress is an organisms response to a stressor such as an environmental condition. Stress is the method of reacting to a challenge. Stimuli that alter an organisms environment are responded to by multiple systems in the body, the autonomic nervous system and hypothalamic-pituitary-adrenal axis are two major systems that respond to stress. The second major physiological stress, the HPA axis regulates the release of cortisol, the SAM and HPA axes are regulated by a wide variety of brain regions, including the limbic system, prefrontal cortex, amygdala, hypothalamus, and stria terminalis. Through these mechanisms, stress can alter memory functions, reward, immune function, metabolism, definitions of stress differ, however, one system proposed by Elliot and Eisdorfer suggests five types of stress. The five types of stress are labeled acute time limited stressors, brief naturalistic stressors, stressful event sequence, chronic stressors, acute time limited stressors involve a short term challenge, while brief naturalistic stressors involve an event that is normal but nevertheless challenging. Stressful event sequences are a stressor that occur, and continue to yield stress into the immediate future, chronic stressors are stressors that involve exposure to a long-term stressor. A distant stressor is a stressor that isnt immediate, there is likely a connection between stress and illness. Theories of the stress–illness link suggest that both acute and chronic stress can cause illness, and several studies have suggested such a link, according to these studies, both acute and chronic stress can lead to changes in behavior and in physiology. Behavioral changes can include smoking, changes in eating habits and physical activity, physiological changes can include changes in sympathetic activation or HPA activity, and immunological function. However, there is variability in the link between stress and illness. The HPA axis regulates many bodily functions, both behavioral and physiological, through the release of glucocorticoid hormones, the HPA axis activity varies according to the circadian rhythm, with a spike in the morning. The axis involves the release of corticotropin releasing hormone and vasopressin from the hypothalamus which stimulates the pituitary to secrete ACTH, ACTH may then stimulate the adrenal glands to secrete cortisol. The HPA axis is subject to feedback regulation as well. The release of CRH and VP are regulated by descending glutaminergic and GABAergic pathways from the amygdala, increased cortisol usually acts to increase blood glucose, blood pressure, and surpasses lysosomal, and immunological activity. Under other circumstances, however, the activity may differ, increased cortisol also favors habit based learning, by favoring memory consolidation of emotional memories. Selye demonstrated that stress decreases adaptability of an organism and proposed to describe the adaptability as a special resource, in recent works, it is considered as an internal coordinate on the dominant path in the model of adaptation. Stress can make the more susceptible to physical illnesses like the common cold
11.
Wikidata
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Wikidata is a collaboratively edited knowledge base operated by the Wikimedia Foundation. It is intended to provide a source of data which can be used by Wikimedia projects such as Wikipedia. This is similar to the way Wikimedia Commons provides storage for files and access to those files for all Wikimedia projects. Wikidata is powered by the software Wikibase, Wikidata is a document-oriented database, focused on items. Each item represents a topic and is identified by a number, prefixed with the letter Q—for example. This enables the basic information required to identify the topic the item covers to be translated without favouring any language, information is added to items by creating statements. Statements take the form of pairs, with each statement consisting of a property. The creation of the project was funded by donations from the Allen Institute for Artificial Intelligence, the Gordon and Betty Moore Foundation, at this time, only the first phase was available. Historically, a Wikipedia article would include a list of links, being links to articles on the same topic in other editions of Wikipedia. Initially, Wikidata was a repository of interlanguage links. No Wikipedia language editions were able to access Wikidata, so they needed to continue to maintain their own lists of interlanguage links, on 14 January 2013, the Hungarian Wikipedia became the first to enable the provision of interlanguage links via Wikidata. This functionality was extended to the Hebrew and Italian Wikipedias on 30 January, to the English Wikipedia on 13 February, on 23 September 2013, phase 1 went live on Wikimedia Commons. The first aspects of the second phase were deployed on 4 February 2013, the values were initially limited to two data types, with more data types to follow later. The first new type, string, was deployed on 6 March, the ability of the various language editions of Wikipedia to access data added to Wikidata as part of phase two was rolled out progressively between 27 March and 25 April 2013. On 16 September 2015, Wikidata began allowing so-called arbitrary access, for example, in the past the article about Berlin you could not access data about Germany, but with arbitrary access it could. On 27 April 2016 arbitrary access was activated on Wikimedia Commons, phase 3 will involve database querying and the creation of lists based on data stored on Wikidata. As of October 2016 two tools for querying Wikidata were available, AutoList and PetScan, additionally to a public SPARQL endpoint, there is concern that the project is being influenced by lobbying companies, PR professionals and search engine optimizers. As of December 2015, according to Wikimedia statistics, half of the information in Wikidata is unsourced, another 30% is labeled as having come from Wikipedia, but with no indication as to which article
