The INDIVIDUALIST

A Wiki about biochemical individuality

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Lewis Blood Group

The Lewis determinants are structurally related to determinants of the ABO and the H/h blood group systems. They are assembled by sequential addition of specific monosaccharides onto terminal saccharide precursor chains on glycolipids or glycoproteins. On the erythrocyte surface they reside on glycolipids. In contrast to the other blood group antigens, the synthesis of these glycolipids does not occur in erythroid tissues, but they are acquired by the erythrocyte membranes from other tissues through circulating lipoproteins.

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PROP and PTC Taster Polymorphisms

In 1931 Fox (1) observed that to some individuals the simple chemical compound phenylthiocarbamide (PTC), has an intensely bitter taste, while to others it is tasteless. Being a chemist he also showed that a number of other closely related substances were tested by the PTC tasters but not by the non-tasters. The ability to taste these substances was shown by Blaklee (2) and by Snyder (3) to behave as a Mendelian dominant character.

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Kell Blood Group

The Kell blood group (also known as the Kell antigen system or Kell-Cellano system) is determined by a group of antigens on the human red blood cell surface. Kell antigens are targets for autoimmune or alloimmune diseases which destroy red blood cells. The Kell antigens are peptides found within the kell protein, a 93 kilodalton transmembrane zinc-dependent endopeptidase which is responsible for cleaving endothelin-3. (4) (5)

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Longevity

Longevity is defined as long life or the length of a person's life (life expectancy). Reflections on longevity have usually gone beyond acknowledging the basic shortness of human life and have included thinking about methods to extend life. Longevity has been a topic not only for the scientific community but also for writers of travel, science fiction and utopian novels. The longest human lifespan on record that has been authenticated is the 122 years 164 days of Jeanne Calment, though fiction, legend, and mythology have proposed or claimed vastly longer lifespans in the past or future and longevity myths frequently allege them to exist in the present.

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ABO and Secretor Blood group Genetics

Glycosphingolipids carrying A or B oligosaccharides are integral parts of the membranes of RBCs, epithelial and endothelial cells; they are also present in soluble form in plasma. Glycoproteins that carry identical oligosaccharides are responsible for the A and B activity of secreted body fluids such as saliva. A and B oligosaccharides that lack carrier protein or lipid molecules are found in milk and urine.

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Transcription (DNA transcription)

Transcription is the process through which a DNA sequence is enzymatically copied by an RNA polymerase to produce a complementary RNA. Or, in other words, the transfer of genetic information from DNA into RNA. In the case of protein-encoding DNA, transcription is the beginning of the process that ultimately leads to the translation of the genetic code (via the mRNA intermediate) into a functional peptide or protein. Transcription has some proofreading mechanisms, but they are fewer and less effective than the controls for DNA; therefore, transcription has a lower copying fidelity than DNA replication.

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Mitochrondrial DNA Haplogroups

In human genetics, Human mitochondrial DNA haplogroups are haplogroups defined by differences in human mitochondrial DNA. These haplogroups trace the matrilineal inheritance of modern humans back to human origins in Africa and the subsequent spread across the globe.

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William Boyd

William Clouser Boyd, American Serologist, Lectinologist, Immunochemist, Geneticist, Archeologist, Author and Educator. Born at Dearborn, Missouri. Educated at Harvard and Boston University. Professor of Immunochemistry, Boston University. Born 4 Mar 1903; died 19 Feb 1983.

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Cystine

Cystine is an organic compound described by the formula (SCH2CH(NH2)CO2H)2. This colourless amino acid melts at 247 -249 °C. It forms upon oxidation of a pair of cysteine molecules. It was discovered in 1810 by William Hyde Wollaston but was not recognized as a component of proteins until it was isolated from the horn of a cow in 1899.(6) Cystine is found in most proteins, and makes a significant contribution to the tertiary structure of most proteins. Cystine is partially responsible for the formation of a gluten matrix in bread, along with hydrogen bonding and hydrophobic interactions. The acid hydrolysis of two kilograms of human hair affords about 100 grams of cystine.(7)

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Cysteine

Cysteine is a naturally occurring, sulfur-containing amino acid that is a building block to most proteins. Cysteine is unique among the twenty common amino acids because it contains a thiol group. Thiol groups can undergo oxidation; a pair of cysteine residues is oxidised, producing cystine, a disulfide-containing derivative. This reaction is reversible. The disulphide bonds of cystine are crucial to defining the structures of many proteins. Related to its redox behavoir, cysteine is incorporated into many proteins that are redox-active, such as the antioxidant glutathione. Cysteine is named after cystine, which comes from the Greek word kustis meaning bladder − cystine was first isolated from kidney stones.

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Histidine

Histidine is one of the 20 most common natural amino acids present in proteins. In the nutritional sense, in humans, histidine is considered an essential amino acid, but mostly only in children. The imidazole side chains and the relatively neutral pK of histidine (ca 6.0) mean that relatively small shifts in cellular pH will change its charge. For this reason, this amino acid side chain finds its way into considerable use as a co-ordinating ligand in metalloproteins, and also as a catalytic site in certain enzymes. The imidazole side chain has two nitrogens with different properties: One is bound to hydrogen and donates its lone pair to the aromatic ring and as such is slighty acidic, whereas the other one donates only one electron to the ring so it has a free lone pair and is basic. These properties are exploited in different ways in proteins. In catalytic triads, the basic nitrogen of histidine is used to abstract a proton from serine, threonine or cysteine to activate it as a nucleophile. In a histidine proton shuttle, histidine is used to quickly shuttle protons, it can do this by abstracting a proton with its basic nitrogen to make a positively-charged intermediate and then use another molecule, a buffer, to extract the proton from its acidic nitrogen. In carbonic anhydrases, a histidine proton shuttle is utilized to rapidly shuttle protons away from a zinc-bound water molecule to quickly regenerate the active form of the enzyme.

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Valine

Valine is one of the 20 proteinogenic amino acids. Nutritionally, valine is also an essential amino acid. It is named after the plant valerian.

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Aspartic acid

Aspartic acid (Asp), also known as aspartate, the name of its anion, is one of the 20 natural proteinogenic amino acids which are the building blocks of proteins.

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Lysine

Lysine is one of the 20 amino acids normally found in proteins. With its 4-aminobutyl side-chain, it is classified as a basic amino acid, along with arginine and histidine. It is an essential amino acid, and the human nutritional requirement is 1–1.5 g daily. A deficiency in lysine can result in a deficiency in niacin (which is a B Vitamin). This can cause the disease pellagra. Lysine can also be used as a nutritional supplement to help against herpes.

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Zinc finger

A zinc finger is a protein domain that can bind to DNA. A zinc finger consists of two antiparallel β strands, and an α helix. One very well explored subset of zinc-fingers (the C2H2 class) comprises a pair of cysteine residues in the beta sheets and two histidine residues in the alpha helix which are responsible for binding a zinc ion.

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Asparagine

Asparagine is one of the 20 most common natural amino acids on Earth. It has carboxamide as the side chain's functional group. It is considered a non-essential amino acid.

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Arginine

Arginine (Arg) is an α-amino acid. The L-form is one of the 20 most common natural amino acids. In mammals, arginine is classified as a semiessential or conditionally essential amino acid, depending on the developmental stage and health status of the individual.

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Homeobox (Hox) Gene

A homeobox (or homoeobox) is a DNA sequence found within genes that are involved in the regulation of development (morphogenesis) of animals, fungi and plants. Genes that have a homeobox are called homeobox genes and form the homeobox gene family.

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Cysteine metabolism

Cysteine metabolism is comprised of the biological pathways that consume or create cysteine. The pathways of different amino acids and other metabolites interweave and overlap to creating complex systems.

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Functome

A functome is the whole set of functional entities in a cell, tissue, organ, organism, and species. Functomics is the scientific discipline of studying the functional entities in biological cells.

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Alanine

Alanine (Ala) also 2-aminopropanoic acid is a non-essential α-amino acid. It exists as two distinct enantiomers - L-alanine and D-alanine. L-alanine is one of the 20 amino acids most widely used in protein synthesis, second to leucine, accounting for 7.8% of the primary structure in a sample of 1,150 proteins (8). D-alanine occurs in bacterial cell walls and in some peptide antibiotics.

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Serine

Serine is an organic compound, one of the 20 amino acids commonly found in animal proteins. Only the L-stereoisomer appears in mammalian protein. It is not essential to the human diet, since it can be synthesized in the body from other metabolites, including glycine. Serine was first obtained from silk protein, a particularly rich source, in 1865. Its name is derived from the Latin for silk, sericum. Serine's structure was established in 1902.

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Proline

L-Proline is one of the twenty proteinogenic units which are used in living organisms as the building blocks of proteins. The other nineteen units are all primary amino acids, but due to the (3-carbon) cyclic sidechain binding back to the nitrogen of the backbone, proline lacks a primary amine group (−NH2). The nitrogen in proline is properly referred to as a secondary amine. Proline is sometimes called an imino acid, but this is not correct, as imines contain a carbon-nitrogen double bond. The side chain binding to the nitrogen prevents rotation around the phi torsion angle, giving proline unique structural properties.

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Threonine

Threonine is one of the 20 natural amino acids. Nutritionally, in humans, threonine is an essential amino acid.

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Hypothalamic-pituitary-adrenal axis (HPA axis)

The hypothalamic-pituitary-adrenal axis (HPA axis) is a major part of the neuroendocrine system that controls reactions to stress and has important functions in regulating various body processes such as digestion, the immune system and energy usage. Species from humans to the most ancient organisms share components of the HPA axis. It is the mechanism for a set of interactions among glands, hormones and parts of the mid-brain that mediate a general adaptation syndrome.

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Glutathione

Glutathione (GSH), whose IUPAC name is 2-amino-5-{[2-[(carboxymethyl)amino]-1-(mercaptomethyl)-2-oxoethyl]amino}-5-oxopentanoic acid, is γ-glutamylcysteinylglycine, a tripeptide. It contains an unusual peptide linkage between the amine group of cysteine and the carboxyl group of the glutamate side chain. Glutathione, an antioxidant, protects cells from toxins such as free radicals (9).

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Purine

Purine is a heterocyclic aromatic organic compound, consisting of a pyrimidine ring fused to an imidazole ring.

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Pyrimidine

Pyrimidine is a heterocyclic aromatic organic compound similar to benzene and pyridine, containing two nitrogen atoms at positions 1 and 3 of the six-member ring. It is isomeric with two other forms of diazine.

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Uracil

Uracil is a common naturally occurring pyrimidine(10). Uracil was originally discovered in 1900 and it was isolated by hydrolysis of yeast nuclein that was found in bovine thymus and spleen, herring sperm, and wheat germ(11). Uracil is a planar, unsaturated compound that has the ability to absorb light(12).

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Guanine

Guanine is one of the five main nucleobases found in the nucleic acids DNA and RNA; the others being adenine, cytosine, thymine, and uracil. With the formula C5H5N5O, guanine is a derivative of purine, consisting of a fused pyrimidine-imidazole ring system with conjugated double bonds. Being unsaturated, the bicyclic molecule is planar. The guanine nucleoside is called guanosine.

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Thymine

Thymine, also known as 5-methyluracil, is a pyrimidine nucleobase. As the name implies, thymine may be derived by methylation of uracil at the 5th carbon. Thymine is found in the nucleic acid DNA. In RNA thymine is replaced with uracil in most cases. In DNA, thymine(T) binds to adenine (A) via two hydrogen bonds to assist in stabilizing the nucleic acid structures.

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Cytosine

Cytosine is one of the 5 main nucleobases used in storing and transporting genetic information within a cell in the nucleic acids DNA and RNA. It is a pyrimidine derivative, with a heterocyclic aromatic ring and two substituents attached (an amine group at position 4 and a keto group at position 2). The nucleoside of cytosine is cytidine. In Watson-Crick base pairing, it forms three hydrogen bonds with guanine.

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Neutral theory of molecular evolution

The neutral theory of molecular evolution (also, simply the neutral theory of evolution) is an influential theory that was introduced with provocative effect by Motoo Kimura in the late 1960s and early 1970s. Although the theory was received by some as an argument against Darwin's theory of evolution by natural selection, Kimura and most evolutionary biologists today maintain that the two theories are compatible. The theory attributes a large role to genetic drift.

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Motoo Kimura

Motoo Kimura (木村資生 Kimura Motoo) (November 13, 1924 - November 13, 1994). Born in Okazaki, Aichi Prefecture, Kimura was a highly influential Japanese mathematical biologist working mostly in the field of theoretical population genetics, although he did not have any formal training in mathematics (13).

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TEP1 telomerase-associated protein 1

This gene product is a component of the ribonucleoprotein complex responsible for telomerase activity which catalyzes the addition of new telomeres on the chromosome ends. The telomerase-associated proteins are conserved from ciliates to humans.

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Adenine

Adenine is one of the two purine nucleobases used in forming nucleotides of the nucleic acids DNA and RNA. In DNA, adenine binds to thymine via two hydrogen bonds to assist in stabilizing the nucleic acid structures. In RNA, adenine binds to uracil, which is used in the cytoplasm for protein synthesis.

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Nucleotide

A nucleotide is a chemical compound that consists of a heterocyclic base, a sugar, and one or more phosphate groups. In the most common nucleotides the base is a derivative of purine or pyrimidine, and the sugar is the pentose (five-carbon sugar) deoxyribose or ribose.

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Transcriptome

Since the completion of the human genome project, a great deal of work has been carried out on analysing the results of the sequencing project. It has become clear that only a small percentage of the genome actually encodes proteins. The remaining genomic content is currently a topic of great interest. Traditional ideas of "junk DNA" and gene Introns which serve no purpose are increasingly being challenged with newer theories and discoveries such as micro RNA's, antisense RNA's and other "non-coding" RNA's.

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Receptor antagonist

In medicine and biology, a receptor antagonist is a substance that inhibits the normal physiological function of a receptor. Many drugs work by blocking the action of endogenous receptor agonists such as hormones and neurotransmitters.

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G-protein-coupled receptors

G protein-coupled receptors (GPCRs), also known as seven transmembrane receptors, heptahelical receptors, or 7TM receptors, are a protein family of transmembrane receptors that transduce an extracellular signal (ligand binding) into an intracellular signal (G protein activation). The GPCRs are the largest protein family known, members of which are involved in all types of stimulus-response pathways, from intercellular communication to physiological senses. The diversity of functions is matched by the wide range of ligands recognized by members of the family, from photons (rhodopsin, the archetypal GPCR) to small molecules (in the case of the histamine receptors) to proteins (for example, chemokine receptors). This pervasive involvement in normal biological processes has the consequence of involving GPCRs in many pathological conditions, which has led to GPCRs being the target of 40 to 50% of modern medicinal drugs.

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Ligand

In biochemistry, a ligand is an effector, a molecule that binds to a site on a macromolecule's surface by intermolecular forces, thereby changing the chemical conformation of the macromolecule. Once a molecule's conformation has changed, its ability to function in other chemical reactions is altered. This binding is usually a reversible reaction, i.e. it can be undone. Actual coordinate covalent bonds between a ligand and its target molecule are rare in biological systems. Ligands include substrates, inhibitors, activators, and neurotransmitters.

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Receptor

In biochemistry, a receptor is a protein on the cell membrane or within the cytoplasm or cell nucleus that binds to a specific molecule (a ligand), such as a neurotransmitter, hormone, or other substance, and initiates the cellular response to the ligand. Ligand-induced changes in the behavior of receptor proteins result in physiological changes that constitute the biological actions of the ligands.

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Signal transduction

In biology, signal transduction is any process by which a cell converts one kind of signal or stimulus into another. Processes referred to as signal transduction often involve a sequence of biochemical reactions inside the cell, which are carried out by enzymes and linked through second messengers. Such processes take place in as little time as a millisecond or as long as a few seconds. Slower processes are rarely referred to as signal transduction.

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Proteasome

Proteasomes are complex structures inside cells that break down proteins. Ubiquitin proteasome system or ubiquitin-26S proteasome system, is a barrel-shaped multi-protein complex that can specifically digest other proteins into short polypeptides and amino acids in an ATP-driven reaction. The Ubiquitin proteasome system is essential for many cellular processes including cell cycle, signal transduction and regulation of gene expression. The importance of proteolytic degradation inside cells and the role of ubiquitin in proteolytic pathways was acknowledged in the awarding of the 2004 Nobel Prize in Chemistry to Aaron Ciechanover, Avram Hershko and Irwin Rose.

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Ubiquitin

Ubiquitin is a small regulatory protein that is ubiquitous in eukaryotes. Ubiquitination (or Ubiquitylation) refers to the Post-translational modification of a protein by the covalent attachment (via an isopeptide bond) of one or more ubiquitin monomers. Ubiquitin (originally, Ubiquitous Immunopoeitic Polypeptide) was first identified in 1975 as an 8.5 kDa protein of unknown function expressed universally in living cells. The basic functions of ubiquitin and the components of the ubiquitination pathway were elucidated in the early 1980s in groundbreaking work performed by Aaron Ciechanover, Avram Hershko and Irwin Rose for which the Nobel Prize in Chemistry was awarded in 2004.

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Nuclear Factor kappa B (NF-kB)

NF-κB, or Nuclear Factor kappa B, is a nuclear transcription factor found in all cell types and is involved in cellular responses to stimuli such as stress, cytokines, free radicals, ultraviolet irradiation, and bacterial or viral antigens. NF-κB plays a key role in regulating the immune response to infection. Consistent with this role, incorrect regulation of NF-κB has been linked to cancer, inflammatory and autoimmune diseases, septic shock, viral infection and improper immune development.

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Histone deacetylases (HDAC)

Histone deacetylases (HDAC) (EC number 3.5.1) are a class of enzymes that remove acetyl groups from an ε-N-acetyl lysine amino acid on a histone. Deacetylation restores a positive electric charge, which increases the histone's affinity for DNA. This generally down-regulates DNA transcription by blocking the access of transcription factors.

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Histone methyltransferases (HMT)

Histone methyltransferases (HMT) are enzymes, histone-lysine N-methyltransferase and histone-arginine N-methyltransferase, which catalyze the transfer of one to three methyl groups from the cofactor s-adenosylmethionine to lysine and arginine residues of histone proteins. These proteins often contain an SET (Su(var)3-9, Enhancer of Zeste, Trithorax) domain, however the recently discovered HMT Dot1 lacks the characteristic SET domain.

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Base pair

In molecular biology, two nucleotides on opposite complementary DNA or RNA strands that are connected via hydrogen bonds are called a base pair (often abbreviated bp). In DNA, adenine (A) forms a base pair with thymine (T), as does guanine (G) with cytosine (C). In RNA, thymine is replaced by uracil (U).

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Copy number polymorphisms

Abbreviated CNP, Copy number polymorphisms are a normal variation in DNA due to variation in the number of copies of a sequence within the DNA. Large-scale copy number polymorphisms are common and widely distributed in the human genome.

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RNA Interference (RNAi)

RNA interference (RNAi) is a mechanism in molecular biology where the presence of certain fragments of double-stranded RNA (dsRNA) interferes with the expression of a particular gene which shares a homologous sequence with the dsRNA. RNAi is distinct from other gene silencing phenomena in that silencing can spread from cell to cell and generate heritable phenotypes in first generation progeny when used in Caenorhabditis elegans.

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Genetic polymorphisms in dietary xenobiotic metabolizing enzymes

From: Nowell S and Kadlubar F. 'Cancer and gene variants in enzymes metabolizing dietary xenobiotics'. In: Nutritional Genomics, Edited by Flohe and Joost, copyright 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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Five prime untranslated region (5' UTR)

In eukaryotic genetics, the five prime untranslated region (5' UTR) is a particular section of messenger RNA (mRNA). It precedes the translation initiation site of the gene, bounded on the 5' end by the start of transcription and on the 3' end by the start codon (see Figure 1 for a schematic view). In some viruses it may have additional role in enhancing the expression level or increasing the stability of RNA.

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Open reading frame

An open reading frame or ORF is any sequence of DNA or RNA that can be translated into a protein. In a gene, ORFs are located between the start-code sequence (initiation codon) and the stop-code sequence (termination codon). ORFs are usually encountered when sifting through pieces of DNA while trying to locate a gene.

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Phyletic gradualism

Phyletic gradualism is a macroevolutionary hypothesis rooted in uniformitarianism. The hypothesis states that species continue to adapt to new challenges over the course of their history, gradually becoming new species. Gradualism holds that every individual is the same species as its parents, and that there is no clear line of demarcation between the old species and the new species. It holds that the species is not a fixed type, and that the population, not the individual, evolves. During this process, evolution occurs at a fairly constant rate.

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Punctuated equilibrium

Punctuated equilibrium (or punctuated equilibria) is a theory in evolutionary biology which states that most sexually reproducing species will show little to no evolutionary change throughout their history. When evolution does occur, it happens sporadically (by splitting) and occurs relatively quickly compared to the species' full duration on earth. Punctuated equilibrium is commonly contrasted against the theory of phyletic gradualism, which hypothesizes that most evolution occurs uniformly and by the steady and gradual transformation of whole lineages (anagenesis).

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Stephen Jay Gould

Stephen Jay Gould (September 10, 1941 – May 20, 2002) was an American paleontologist, evolutionary biologist, and historian of science. He was also one of the most influential and widely read writers of popular science of his generation, which led many authors to call him "America's unofficial evolutionist laureate." He spent most of his career teaching at Harvard University and working at the American Museum of Natural History.

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Ontogeny

Ontogeny (also ontogenesis or morphogenesis) describes the origin and the development of an organism from the fertilized egg to its mature form. Ontogeny is studied in developmental biology.

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Recapitulation theory

The theory of recapitulation, also called the biogenetic law or ontogeny recapitulates phylogeny, is a theory in biology which attempts to explain apparent similarities between humans and other animals. First espoused in 1866 by German zoologist Ernst Haeckel, a contemporary of Charles Darwin, the theory has been discredited in its absolute form, although recognized as being partly accurate. In biology, ontogeny is the embryonal development process of a certain species, and phylogeny a species' evolutionary history. Observers have noted various connections between phylogeny and ontogeny, explained them with evolutionary theory and taken them as supporting evidence for that theory.

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J.B.S Haldane

John Burdon Sanderson Haldane (November 5, 1892 - December 1, 1964), who normally used "J.B.S." as a first name, was a British geneticist and evolutionary biologist. He was one of the founders (along with Ronald Fisher and Sewall Wright) of population genetics.

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Paedomorphic variations

In developmental biology, paedomorphosis or juvenification is a phylogenetic change in which the adults of a species retain traits previously seen only in juveniles. Peramorphosis is change in the reverse direction.

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Neoteny

Neoteny describes a process by which paedomorphism is achieved, and is a subject studied in the field of developmental biology. In neoteny, the physiological (or somatic) development of an animal or organism is slowed or delayed. Ultimately this process results in the retention, in the adults of a species, of juvenile physical characteristics well into maturity. The English word neoteny is borrowed from the German Neotenie, the latter constructed from the Greek νέος (young) and τείνειν (to extend).

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CREB Proteins

CREB (cAMP response element-binding) proteins are transcription factors which bind to certain sequences called cAMP response elements in DNA and thereby increase or decrease the transcription of certain genes. CREB proteins are active in many animals, including humans. The typical (somewhat simplified) sequence of events is as follows: a signal arrives at the cell surface, activates the corresponding receptor, which leads to the production of a second messenger such as cAMP or Ca2+, which in turn activates a protein kinase. This protein kinase moves to the cell nucleus, where it activates a CREB protein. The activated CREB molecule then binds to a CRE element, and is then bound to by a CBP (CREB binding protein) which coactivates it, allowing it to switch certain genes on or off. The DNA binding of CREB is mediated via its basic Leucine zipper domain (bZIP domain) as depicted on the picture.

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Phosphodiesterase (PDE)

A phosphodiesterase (PDE) is an enzyme that catalyzes the hydrolysis of phosphodiester bonds. There are 11 families of PDEs, namely PDE1-PDE11.

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Second messengers

In biology, second messengers are low-weight diffusible molecules that are used in signal transduction to relay signals within a cell. They are synthesized or released by specific enzymatic reactions, usually as a result of an external signal that was received by a transmembrane receptor and pre-processed by other membrane-associated proteins. There are three basic types of second messenger molecules:

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Cyclic adenosine monophosphate (cAMP)

Cyclic adenosine monophosphate (cAMP, cyclic AMP or 3'-5'-cyclic adenosine monophosphate) is a molecule that is important in many biological processes; it is derived from adenosine triphosphate (ATP). cAMP is a second messenger, used for intracellular signal transduction, such as transferring the effects of hormones like glucagon and adrenaline, which cannot get through the cell membrane. Its main purpose is the activation of protein kinases; it is also used to regulate the passage of Ca2+ through ion channels.

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Ploidy

Ploidy indicates the number of copies of the basic number of chromosomes. The number of basic sets of chromosomes in an organism is called the monoploid number (x). The ploidy of cells can vary within an organism. In humans, most cells are diploid (containing one set of chromosomes from each parent), though sex cells (sperm and oocytes) are haploid. In contrast, tetraploidy (four sets of chromosomes), a type of polyploidy, is not uncommon in healthy plant species.

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Maternal effect

A maternal effect, in genetics, is the phenomena where the genotype of a mother is expressed in the phenotype of its offspring, unaltered by paternal genetic influence. This is usually attributed to maternally produced molecules, such as mRNAs, that are deposited in the egg cell. Maternal effect genes often affect early developmental processes such as axis formation.

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Phenotypic plasticity

The ability of an organism with a given genotype to change its phenotype in response to changes in the environment is called phenotypic plasticity. Such plasticity in some cases expresses as several highly morphologically distinct results; in other cases, a continuous norm of reaction describes the functional interrelationship of a range of environments to a range of phenotypes.

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Occurrence of A and B Antigens in the Human Body Outside of the Erythrocytes

The antigens A and B are not restricted to the red cells of the blood. They seem to occur in all cells and tissue fluids, except the cerebrospinal fluid, testicle, lens, chorion frondosum of the placenta, hair, compact bone, cartilage,' epithelial cells of the skin, and the nails. This table, taken from Boyd (14) shows the relative amounts in the parts of the body which have been studied quantitatively.

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Rheology

Rheology is the study of the deformation and flow of matter under the influence of an applied stress. The term was coined by Eugene Bingham, a professor at Lehigh University, in 1920, from a suggestion by a colleague, Markus Reiner. The term was inspired by Heraclitus's famous expression panta rei, "everything flows".

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1. Fox AL. Proc. Nat. Acad. Sci. (18) 115-120; 1932

2. Blaklee AF. Proc. Nat. Acad. Sci. (18) 120-130; 1932

3. Snyder LH. Ohio J. Science. (32) 436-440; 1932

4. Lee S, Wu X, Reid M, Zelinski T, Redman C. Molecular basis of the Kell (K1) phenotype. Blood. 1995 Feb 15;85(4):912-6. PMID 7849312

5. Lee S, Lin M, Mele A, Cao Y, Farmar J, Russo D, Redman C. Proteolytic processing of big endothelin-3 by the kell blood group protein. Blood. 1999 Aug 15;94(4):1440-50. PMID 10438732

6. "cystine." Encyclopædia Britannica. 2007. Encyclopædia Britannica Online. 27 July 2007 www.britannica.com/eb/article-9028437/cystine

7. Gortner, R. A.; W. F. Hoffman, W. F. “l-Cystine” Organic Syntheses, Collected Volume 1, p.194 (1941). http://www.orgsyn.org/orgsyn/pdfs/CV1P0194.pdf

8. Doolittle RF (1989). "Redundancies in protein sequences" in Prediction of Protein Structures and the Principles of Protein Conformation. (Fasman GD, ed.), pp 599-623, Plenum Press, New York.

9. Strużńka, L. and Chalimoniuk, M. and Sulkowski, G. (September 2005). "The role of astroglia in Pb-exposed adult rat brain with respect to glutamate toxicity". Toxicology 212 (2-3): 185-194.

10. Garrett, Reginald H.; Grisham, Charles M. Principles of Biochemistry with a Human Focus. United States: Brooks/Cole Thomson Learning, 1997.

11. Brown, D.J. Heterocyclic Compounds: Thy Pyrimidines. Vol 52. New York: Interscience, 1994.

12. Horton, Robert H.; et al.Principles of Biochemistry. 3rd ed. Upper Saddle River, NJ: Prentice Hall, 2002.

13. Crow, J.F. (1995). "Motoo Kimura (1924-1994)". Genetics 140: 1-5.

14. Boyd, W. Fundamentals of Immunology, First Edition, Interscience, 1943

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