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Lactobacillus Acidophilus
''Lactobacillus acidophilus'' (New Latin 'acid-loving milk-bacillus') is a rod-shaped, Gram-positive, homofermentative, anaerobic microbe first isolated from infant feces in the year 1900. The species is most commonly found in humans, specifically the gastrointestinal tract, oral cavity, and vagina, as well as various fermented foods such as fermented milk or yogurt. The species most readily grows at low pH levels (below 5.0), and has an optimum growth temperature of 37 °C. Certain strains of ''L. acidophilus'' show strong probiotic effects, and are commercially used in dairy production. The genome of ''L. acidophilus'' has been sequenced. ''L. acidophilus'' has antagonistic effects on the growth for ''Staphylococcus aureus, Escherichia coli, Salmonella typhimurium,'' and ''Clostridium perfringens''. Out of the four organisms, ''Staphylococcus aureus'' is the most affected. Along with ''S. aureus'', the other Gram-positive bacteria, ''C. perfringens,'' was affected more by ' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ernst Moro
Ernst Moro (8 December 1874 in Laibach, Duchy of Carniola, Austria-Hungary, today Ljubljana, Slovenia – 1951) was an Austrian physician and pediatrician who was the first in western medicine to describe the infant reflex that was named after him ( Moro reflex). Career Moro studied medicine in Graz, Austria, getting his M.D. in 1899. From 1901 to 1902 he worked with Theodor Escherich (1857–1911) in Vienna, the discoverer of the Escherichia coli bacterium. He earned his habilitation in pediatrics in Munich in 1906, and became a professor of pediatrics in the University of Heidelberg in 1911. Besides the Moro reflex he became also known for the following: * Proved the sterility of the normal small intestine * Discovered that breast-fed children have stronger bactericidal activity in their blood than bottle-fed ones * First described the irritable colon syndrome or recurrent abdominal pain ("Nabelkoliken") in children * Isolated the bacterium ''Lactobacillus acidophilu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Prokaryote
A prokaryote () is a single-celled organism that lacks a nucleus and other membrane-bound organelles. The word ''prokaryote'' comes from the Greek πρό (, 'before') and κάρυον (, 'nut' or 'kernel').Campbell, N. "Biology:Concepts & Connections". Pearson Education. San Francisco: 2003. In the two-empire system arising from the work of Édouard Chatton, prokaryotes were classified within the empire Prokaryota. But in the three-domain system, based upon molecular analysis, prokaryotes are divided into two domains: ''Bacteria'' (formerly Eubacteria) and '' Archaea'' (formerly Archaebacteria). Organisms with nuclei are placed in a third domain, Eukaryota. In the study of the origins of life, prokaryotes are thought to have arisen before eukaryotes. Besides the absence of a nucleus, prokaryotes also lack mitochondria, or most of the other membrane-bound organelles that characterize the eukaryotic cell. It was once thought that prokaryotic cellular components within the c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
LuxS
The enzyme S-ribosylhomocysteine lyase (EC 4.4.1.21) catalyzes the reaction :''S''-(5-deoxy-D-ribos-5-yl)-L-homocysteine = L-homocysteine + (4''S'')-4,5-dihydroxypentan-2,3-dione Nomenclature This enzyme belongs to the family of lyases, specifically the class of carbon-sulfur lyases. The systematic name of this enzyme class is ''S''-(5-deoxy-D-ribos-5-yl)-L-homocysteine L-homocysteine-lyase 4''S'')-4,5-dihydroxypentan-2,3-dione-forming''. Other names in common use include ''S''-ribosylhomocysteinase, and LuxS. This enzyme participates in methionine metabolism. Structure and function LuxS is a homodimeric iron-dependent metalloenzyme containing two identical tetrahedral metal-binding sites similar to those found in peptidases and amidases. Furthermore, LuxS is involved in the synthesis of autoinducer AI-2 (autoinducer-2), which mediates quorum sensing in roughly half of bacterial species. AI-2, a furanosyl borate diester, is a small signaling molecule generated by ba ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Autoinducer
Autoinducers are signaling molecules that are produced in response to changes in cell-population density. As the density of quorum sensing bacterial cells increases so does the concentration of the autoinducer. Detection of signal molecules by bacteria acts as stimulation which leads to altered gene expression once the minimal threshold is reached. Quorum sensing is a phenomenon that allows both Gram-negative and Gram-positive bacteria to sense one another and to regulate a wide variety of physiological activities. Such activities include symbiosis, virulence, motility, antibiotic production, and biofilm formation. Autoinducers come in a number of different forms depending on the species, but the effect that they have is similar in many cases. Autoinducers allow bacteria to communicate both within and between different species. This communication alters gene expression and allows bacteria to mount coordinated responses to their environments, in a manner that is comparable to be ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quorum Sensing
In biology, quorum sensing or quorum signalling (QS) is the ability to detect and respond to cell population density by gene regulation. As one example, QS enables bacteria to restrict the expression of specific genes to the high cell densities at which the resulting phenotypes will be most beneficial. Many species of bacteria use quorum sensing to coordinate gene expression according to the density of their local population. In a similar fashion, some social insects use quorum sensing to determine where to nest. Quorum sensing in pathogenic bacteria activates host immune signaling and prolongs host survival, by limiting the bacterial intake of nutrients, such as tryptophan, which further is converted to serotonin. As such, quorum sensing allows a commensal interaction between host and pathogenic bacteria. Quorum sensing may also be useful for cancer cell communications. In addition to its function in biological systems, quorum sensing has several useful applications for computing ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chaperone (protein)
In molecular biology, molecular chaperones are proteins that assist the conformational folding or unfolding of large proteins or macromolecular protein complexes. There are a number of classes of molecular chaperones, all of which function to assist large proteins in proper protein folding during or after synthesis, and after partial denaturation. Chaperones are also involved in the translocation of proteins for proteolysis. The first molecular chaperones discovered were a type of assembly chaperones which assist in the assembly of nucleosomes from folded histones and DNA. One major function of molecular chaperones is to prevent the aggregation of misfolded proteins, thus many chaperone proteins are classified as heat shock proteins, as the tendency for protein aggregation is increased by heat stress. The majority of molecular chaperones do not convey any steric information for protein folding, and instead assist in protein folding by binding to and stabilizing folding intermed ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Epithelial Tissues Simple Columnar Epithelium (41006485014)
Epithelium or epithelial tissue is one of the four basic types of animal tissue, along with connective tissue, muscle tissue and nervous tissue. It is a thin, continuous, protective layer of compactly packed cells with a little intercellular matrix. Epithelial tissues line the outer surfaces of organs and blood vessels throughout the body, as well as the inner surfaces of cavities in many internal organs. An example is the epidermis, the outermost layer of the skin. There are three principal shapes of epithelial cell: squamous (scaly), columnar, and cuboidal. These can be arranged in a singular layer of cells as simple epithelium, either squamous, columnar, or cuboidal, or in layers of two or more cells deep as stratified (layered), or ''compound'', either squamous, columnar or cuboidal. In some tissues, a layer of columnar cells may appear to be stratified due to the placement of the nuclei. This sort of tissue is called pseudostratified. All glands are made up of epith ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pan-genome
In the fields of molecular biology and genetics, a pan-genome (pangenome or supragenome) is the entire set of genes from all strains within a clade. More generally, it is the union of all the genomes of a clade. The pan-genome can be broken down into a "core pangenome" that contains genes present in all individuals, a "shell pangenome" that contains genes present in two or more strains, and a "cloud pangenome" that contains genes only found in a single strain. Some authors also refer to the cloud genome as "accessory genome" containing 'dispensable' genes present in a subset of the strains and strain-specific genes. Note that the use of the term 'dispensable' has been questioned, at least in plant genomes, as accessory genes play "an important role in genome evolution and in the complex interplay between the genome and the environment". The field of study of the pangenome is called pangenomics. The genetic repertoire of a bacterial species is much larger than the gene content ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
GC-content
In molecular biology and genetics, GC-content (or guanine-cytosine content) is the percentage of nitrogenous bases in a DNA or RNA molecule that are either guanine (G) or cytosine (C). This measure indicates the proportion of G and C bases out of an implied four total bases, also including adenine and thymine in DNA and adenine and uracil in RNA. GC-content may be given for a certain fragment of DNA or RNA or for an entire genome. When it refers to a fragment, it may denote the GC-content of an individual gene or section of a gene (domain), a group of genes or gene clusters, a non-coding region, or a synthetic oligonucleotide such as a primer. Structure Qualitatively, guanine (G) and cytosine (C) undergo a specific hydrogen bonding with each other, whereas adenine (A) bonds specifically with thymine (T) in DNA and with uracil (U) in RNA. Quantitatively, each GC base pair is held together by three hydrogen bonds, while AT and AU base pairs are held together by two hydrogen bon ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Genome
In the fields of molecular biology and genetics, a genome is all the genetic information of an organism. It consists of nucleotide sequences of DNA (or RNA in RNA viruses). The nuclear genome includes protein-coding genes and non-coding genes, other functional regions of the genome such as regulatory sequences (see non-coding DNA), and often a substantial fraction of 'junk' DNA with no evident function. Almost all eukaryotes have mitochondria and a small mitochondrial genome. Algae and plants also contain chloroplasts with a chloroplast genome. The study of the genome is called genomics. The genomes of many organisms have been sequenced and various regions have been annotated. The International Human Genome Project reported the sequence of the genome for ''Homo sapiens'' in 200The Human Genome Project although the initial "finished" sequence was missing 8% of the genome consisting mostly of repetitive sequences. With advancements in technology that could handle sequen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
DNA Polymerase III Holoenzyme
DNA polymerase III holoenzyme is the primary enzyme complex involved in prokaryotic DNA replication. It was discovered by Thomas Kornberg (son of Arthur Kornberg) and Malcolm Gefter in 1970. The complex has high processivity (i.e. the number of nucleotides added per binding event) and, specifically referring to the replication of the '' E.coli'' genome, works in conjunction with four other DNA polymerases (Pol I, Pol II, Pol IV, and Pol V). Being the primary holoenzyme involved in replication activity, the DNA Pol III holoenzyme also has proofreading capabilities that corrects replication mistakes by means of exonuclease activity reading 3'→5' and synthesizing 5'→3'. DNA Pol III is a component of the replisome, which is located at the replication fork. Components The replisome is composed of the following: *2 DNA Pol III enzymes, each comprising α, ε and θ subunits. (It has been proven that there is a third copy of Pol III at the replisome.) **the α subunit (encode ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Okazaki Fragments
Okazaki fragments are short sequences of DNA nucleotides (approximately 150 to 200 base pairs long in eukaryotes) which are synthesized discontinuously and later linked together by the enzyme DNA ligase to create the lagging strand during DNA replication. They were discovered in the 1960s by the Japanese molecular biologists Reiji and Tsuneko Okazaki, along with the help of some of their colleagues. During DNA replication, the double helix is unwound and the complementary strands are separated by the enzyme DNA helicase, creating what is known as the DNA replication fork. Following this fork, DNA primase and DNA polymerase begin to act in order to create a new complementary strand. Because these enzymes can only work in the 5’ to 3’ direction, the two unwound template strands are replicated in different ways. One strand, the leading strand, undergoes a continuous replication process since its template strand has 3’ to 5’ directionality, allowing the polymerase assemb ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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