The Golgi apparatus, known as the Golgi complex, Golgi body, or simply the Golgi, is an organelle found in most eukaryotic cells. It was identified in 1897 by the Italian scientist Camillo Golgi, part of the cellular endomembrane system, the Golgi apparatus packages proteins into membrane-bound vesicles inside the cell before the vesicles are sent to their destination. The Golgi apparatus resides at the intersection of the secretory, owing to its large size and distinctive structure, the Golgi apparatus was one of the first organelles to be discovered and observed in detail. It was discovered in 1898 by Italian physician Camillo Golgi during an investigation of the nervous system, after first observing it under his microscope, he termed the structure the internal reticular apparatus. Some doubted the discovery at first, arguing that the appearance of the structure was merely an illusion created by the observation technique used by Golgi. With the development of modern microscopes in the 20th century, the discovery was confirmed, early references to the Golgi referred to it by various names including the Golgi–Holmgren apparatus, Golgi–Holmgren ducts, and Golgi–Kopsch apparatus.
The term Golgi apparatus was used in 1910 and first appeared in the literature in 1913. Among eukaryotes, the localization of the Golgi apparatus differs. In mammals, a single Golgi apparatus complex is located near the cell nucleus. Tubular connections are responsible for linking the stacks together and tubular connections of the Golgi apparatus are dependent on microtubules. If microtubules are experimentally depolymerized, the Golgi apparatus loses connections, in yeast, multiple Golgi apparatuses are scattered throughout the cytoplasm. In plants, Golgi stacks are not concentrated at the centrosomal region, organization of the plant Golgi depends on actin cables and not microtubules. The common feature among Golgi is that they are adjacent to endoplasmic reticulum exit sites, in most eukaryotes, the Golgi apparatus is made up of a series of compartments consisting of two main networks, the cis Golgi network and the trans Golgi network. The CGN is a collection of fused, flattened membrane-enclosed disks known as cisternae, a mammalian cell typically contains 40 to 100 stacks.
Between four and eight cisternae are usually present in a stack and this collection of cisternae is broken down into cis and trans compartments. The TGN is the final structure, from which proteins are packaged into vesicles destined to lysosomes, secretory vesicles. The TGN is usually positioned adjacent to the stacks of the Golgi apparatus, the TGN may act as an early endosome in yeast and plants. There are structural and organizational differences in the Golgi apparatus among eukaryotes, in some yeasts, Golgi stacking is not observed
Bacteria constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a number of shapes, ranging from spheres to rods, Bacteria were among the first life forms to appear on Earth, and are present in most of its habitats. Bacteria inhabit soil, acidic hot springs, radioactive waste, Bacteria live in symbiotic and parasitic relationships with plants and animals. Most bacteria have not been characterised, and only half of the bacterial phyla have species that can be grown in the laboratory. The study of bacteria is known as bacteriology, a branch of microbiology, There are typically 40 million bacterial cells in a gram of soil and a million bacterial cells in a millilitre of fresh water. There are approximately 5×1030 bacteria on Earth, forming a biomass which exceeds that of all plants, Bacteria are vital in many stages of the nutrient cycle by recycling nutrients such as the fixation of nitrogen from the atmosphere. The nutrient cycle includes the decomposition of bodies and bacteria are responsible for the putrefaction stage in this process.
In March 2013, data reported by researchers in October 2012, was published and it was suggested that bacteria thrive in the Mariana Trench, which with a depth of up to 11 kilometres is the deepest known part of the oceans. Other researchers reported related studies that microbes thrive inside rocks up to 580 metres below the sea floor under 2.6 kilometres of ocean off the coast of the northwestern United States. According to one of the researchers, You can find microbes everywhere—theyre extremely adaptable to conditions, the vast majority of the bacteria in the body are rendered harmless by the protective effects of the immune system, though many are beneficial particularly in the gut flora. However several species of bacteria are pathogenic and cause diseases, including cholera, anthrax, leprosy. The most common fatal diseases are respiratory infections, with tuberculosis alone killing about 2 million people per year. In developed countries, antibiotics are used to treat infections and are used in farming, making antibiotic resistance a growing problem.
Once regarded as constituting the class Schizomycetes, bacteria are now classified as prokaryotes. Unlike cells of animals and other eukaryotes, bacterial cells do not contain a nucleus and these evolutionary domains are called Bacteria and Archaea. The ancestors of modern bacteria were unicellular microorganisms that were the first forms of life to appear on Earth, for about 3 billion years, most organisms were microscopic, and bacteria and archaea were the dominant forms of life. In 2008, fossils of macroorganisms were discovered and named as the Francevillian biota, gene sequences can be used to reconstruct the bacterial phylogeny, and these studies indicate that bacteria diverged first from the archaeal/eukaryotic lineage. Bacteria were involved in the second great evolutionary divergence, that of the archaea, eukaryotes resulted from the entering of ancient bacteria into endosymbiotic associations with the ancestors of eukaryotic cells, which were themselves possibly related to the Archaea
N-linked glycosylation, is the attachment of the sugar molecule oligosaccharide known as glycan to a nitrogen atom, in a process called N-glycosylation, studied in biochemistry. This type of linkage is important for both the structure and function of some eukaryotic proteins, the N-linked glycosylation process occurs in eukaryotes and widely in archaea, but very rarely in bacteria. The nature of N-linked glycans attached to a glycoprotein is determined by the protein, different species synthesize different types of N-linked glycan. There are two types of bonds involved in a glycoprotein, bonds between the residues in the glycan and the linkage between the glycan chain and the protein molecule. The sugar moieties are linked to one another in the chain via glycosidic bonds. These bonds are formed between carbon 1 and 4 of the sugar molecules. The formation of glycosidic bond is energetically unfavourable, therefore the reaction is coupled to the hydrolysis of two ATP molecules, on the other hand, the attachment of a glycan residue to a protein requires the recognition of a consensus sequence.
N-linked glycans are almost always attached to the atom of an asparagine side chain that is present as a part of Asn-X-Ser/Thr consensus sequence. In animal cells, the attached to the asparagine is almost inevitably N-acetylglucosamine. This β-linkage is similar to glycosidic bond between the sugar moieties in the structure as described above. Instead of being attached to a hydroxyl group, the anomeric carbon atom is attached to an amide nitrogen. The energy required for this comes from the hydrolysis of a pyrophosphate molecule. Subsequent processing and modification of the chain is carried out in the Golgi apparatus. The synthesis of glycoproteins is thus spatially separated in different cellular compartments, the type of N-glycan synthesised, depends on its accessibility to the different enzymes present within these cellular compartments. However, in spite of the diversity, all N-glycans are synthesised through a pathway with a common core glycan structure. The core glycan structure is made up of two N-acetyl glucosamine and three mannose residues.
This core glycan is elaborated and modified further, resulting in a range of N-glycan structures. The process of N-linked glycosylation starts with the formation of dolichol-linked GlcNAc sugar, dolichol is a lipid molecule composed of repeating isoprene units
A fungus is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. These organisms are classified as a kingdom, which is separate from the other eukaryotic life kingdoms of plants, a characteristic that places fungi in a different kingdom from plants and some protists, is chitin in their cell walls. Similar to animals, fungi are heterotrophs, they acquire their food by absorbing dissolved molecules, growth is their means of mobility, except for spores, which may travel through the air or water. Fungi are the principal decomposers in ecological systems and this fungal group is distinct from the structurally similar myxomycetes and oomycetes. The discipline of biology devoted to the study of fungi is known as mycology, in the past, mycology was regarded as a branch of botany, although it is now known fungi are genetically more closely related to animals than to plants. Abundant worldwide, most fungi are inconspicuous because of the size of their structures.
Fungi include symbionts of plants, animals, or other fungi and they may become noticeable when fruiting, either as mushrooms or as molds. Fungi perform a role in the decomposition of organic matter and have fundamental roles in nutrient cycling. Since the 1940s, fungi have been used for the production of antibiotics, Fungi are used as biological pesticides to control weeds, plant diseases and insect pests. Many species produce bioactive compounds called mycotoxins, such as alkaloids and polyketides, the fruiting structures of a few species contain psychotropic compounds and are consumed recreationally or in traditional spiritual ceremonies. Fungi can break down manufactured materials and buildings, and become significant pathogens of humans, losses of crops due to fungal diseases or food spoilage can have a large impact on human food supplies and local economies. The fungus kingdom encompasses a diversity of taxa with varied ecologies, life cycle strategies. However, little is known of the biodiversity of Kingdom Fungi.
Advances in molecular genetics have opened the way for DNA analysis to be incorporated into taxonomy, phylogenetic studies published in the last decade have helped reshape the classification within Kingdom Fungi, which is divided into one subkingdom, seven phyla, and ten subphyla. The English word fungus is directly adopted from the Latin fungus, used in the writings of Horace, a group of all the fungi present in a particular area or geographic region is known as mycobiota, e. g. the mycobiota of Ireland. Like plants, fungi grow in soil and, in the case of mushrooms, form conspicuous fruit bodies. The fungi are now considered a kingdom, distinct from both plants and animals, from which they appear to have diverged around one billion years ago. Fungi have membrane-bound cytoplasmic organelles such as mitochondria, sterol-containing membranes and they have a characteristic range of soluble carbohydrates and storage compounds, including sugar alcohols and polysaccharides
Protein Data Bank
The Protein Data Bank is a crystallographic database for the three-dimensional structural data of large biological molecules, such as proteins and nucleic acids. The PDB is overseen by a called the Worldwide Protein Data Bank. The PDB is a key resource in areas of structural biology, most major scientific journals, and some funding agencies, now require scientists to submit their structure data to the PDB. Many other databases use protein structures deposited in the PDB, for example, SCOP and CATH classify protein structures, while PDBsum provides a graphic overview of PDB entries using information from other sources, such as Gene ontology. By 1971, one of Meyers programs, SEARCH, enabled researchers to access information from the database to study protein structures offline. SEARCH was instrumental in enabling networking, thus marking the beginning of the PDB. Upon Hamiltons death in 1973, Tom Koeztle took over direction of the PDB for the subsequent 20 years, in January 1994, Joel Sussman of Israels Weizmann Institute of Science was appointed head of the PDB.
In October 1998, the PDB was transferred to the Research Collaboratory for Structural Bioinformatics, the new director was Helen M. Berman of Rutgers University. In 2003, with the formation of the wwPDB, the PDB became an international organization, the founding members are PDBe, RCSB, and PDBj. Each of the four members of wwPDB can act as deposition, data processing, the data processing refers to the fact that wwPDB staff review and annotate each submitted entry. The data are automatically checked for plausibility. The PDB database is updated weekly, the PDB holdings list is updated weekly. As of 14 March 2017, the breakdown of current holdings is as follows,103,514 structures in the PDB have a structure factor file,9,057 structures have an NMR restraint file. 2,826 structures in the PDB have a chemical shifts file, the final conformation of the protein is obtained, in the latter case, by solving a distance geometry problem. A few proteins are determined by cryo-electron microscopy, the significance of the structure factor files, mentioned above, is that, for PDB structures determined by X-ray diffraction that have a structure file, the electron density map may be viewed.
The data of such structures is stored on the electron density server, since 2007, the rate of accumulation of new protein structures appears to have plateaued. The file format used by the PDB was called the PDB file format. This original format was restricted by the width of computer punch cards to 80 characters per line, around 1996, the macromolecular Crystallographic Information file format, mmCIF, which is an extension of the CIF format started to be phased in
Arabidopsis thaliana is a small flowering plant native to Eurasia. A. thaliana is considered a weed, it is found by roadsides, a winter annual with a relatively short life cycle, A. thaliana is a popular model organism in plant biology and genetics. For a complex multicellular eukaryote, A. thaliana has a small genome of approximately 135 megabase pairs. It was the first plant to have its genome sequenced, and is a tool for understanding the molecular biology of many plant traits, including flower development. Arabidopsis thaliana is a plant, usually growing to 20–25 cm tall. The leaves form a rosette at the base of the plant, leaves are covered with small, unicellular hairs. The flowers are 3 mm in diameter, arranged in a corymb, the fruit is a siliqua 5–20 mm long, containing 20–30 seeds. Roots are simple in structure, with a primary root that grows vertically downward. These roots form interactions with rhizosphere bacteria such as Bacillus megaterium, a. thaliana can complete its entire lifecycle in six weeks.
The central stem produces flowers grows after about three weeks, and the flowers naturally self-pollinate. In the lab, A. thaliana may be grown in Petri plates, pots, or hydroponics, the plant was first described in 1577 in the Harz Mountains by Johannes Thal, a physician from Nordhausen, Thüringen, who called it Pilosella siliquosa. In 1753, Carl Linnaeus renamed the plant Arabis thaliana in honor of Thal, in 1842, the German botanist Gustav Heynhold erected the new genus Arabidopsis and placed the plant in that genus. The genus name, comes from Greek, meaning resembling Arabis, thousands of natural inbred accessions of A. thaliana have been collected from throughout its natural and introduced range. These accessions exhibit considerable genetic and phenotypic variation which can be used to study the adaptation of species to different environments. A. thaliana is native to Europe and northwestern Africa and it appears to be native in tropical afroalpine ecosystems. It has been introduced and naturalized worldwide, a. thaliana readily grows and often pioneers rocky and calcareous soils.
It is generally considered a weed, due to its distribution in agricultural fields, railway lines, waste ground. Like most Brassicaceae species, A. thaliana is edible by humans as a salad or cooked, the first mutant in A. thaliana was documented in 1873 by Alexander Braun, describing a double flower phenotype
Amino acids are organic compounds containing amine and carboxyl functional groups, along with a side chain specific to each amino acid. The key elements of an acid are carbon, oxygen. About 500 amino acids are known and can be classified in many ways, in the form of proteins, amino acids comprise the second-largest component of human muscles and other tissues. Outside proteins, amino acids perform critical roles in such as neurotransmitter transport. In biochemistry, amino acids having both the amine and the acid groups attached to the first carbon atom have particular importance. They are known as 2-, alpha-, or α-amino acids and they include the 22 proteinogenic amino acids, which combine into peptide chains to form the building-blocks of a vast array of proteins. These are all L-stereoisomers, although a few D-amino acids occur in bacterial envelopes, as a neuromodulator, twenty of the proteinogenic amino acids are encoded directly by triplet codons in the genetic code and are known as standard amino acids.
The other two are selenocysteine, and pyrrolysine and selenocysteine are encoded via variant codons, for example, selenocysteine is encoded by stop codon and SECIS element. N-formylmethionine is generally considered as a form of methionine rather than as a separate proteinogenic amino acid, codon–tRNA combinations not found in nature can be used to expand the genetic code and create novel proteins known as alloproteins incorporating non-proteinogenic amino acids. Many important proteinogenic and non-proteinogenic amino acids play critical roles within the body. Nine proteinogenic amino acids are called essential for humans because they cannot be created from other compounds by the human body, others may be conditionally essential for certain ages or medical conditions. Essential amino acids may differ between species, because of their biological significance, amino acids are important in nutrition and are commonly used in nutritional supplements and food technology. Industrial uses include the production of drugs, biodegradable plastics, the first few amino acids were discovered in the early 19th century.
In 1806, French chemists Louis-Nicolas Vauquelin and Pierre Jean Robiquet isolated a compound in asparagus that was subsequently named asparagine, cystine was discovered in 1810, although its monomer, remained undiscovered until 1884. Glycine and leucine were discovered in 1820, usage of the term amino acid in the English language is from 1898. Proteins were found to yield amino acids after enzymatic digestion or acid hydrolysis, in the structure shown at the top of the page, R represents a side chain specific to each amino acid. The carbon atom next to the group is called the α–carbon. Amino acids containing an amino group bonded directly to the alpha carbon are referred to as amino acids
The carrot is a root vegetable, usually orange in colour, though purple, red and yellow cultivars exist. Carrots are a form of the wild carrot, Daucus carota, native to Europe. The plant probably originated in Persia and originally cultivated for its leaves, the most commonly eaten part of the plant is the taproot, although the greens are sometimes eaten as well. The domestic carrot has been bred for its greatly enlarged, more palatable. The carrot is a plant in the umbellifer family Apiaceae. At first, it grows a rosette of leaves while building up the enlarged taproot, fast-growing cultivars mature within three months of sowing the seed, while slower-maturing cultivars are harvested four months later. The United Nations Food and Agriculture Organization reports that production of carrots and turnips for the calendar year 2013 was 37.2 million tonnes. Carrots are widely used in many cuisines, especially in the preparation of salads, in Old English, carrots were not clearly distinguished from parsnips, the two were collectively called moru or more.
Various languages still use the word for carrot as they do for root. Molecular and genetic studies, along with history, support the idea that the cultivated/domesticated carrot has a single origin in Central Asia. The wild ancestors of the carrot are likely to have originated in Persia, which remains the centre of diversity for Daucus carota, when they were first cultivated, carrots were grown for their aromatic leaves and seeds rather than their roots. Carrot seeds have been found in Switzerland and Southern Germany dating back to 2000–3000 BC, some close relatives of the carrot are still grown for their leaves and seeds, for example, cilantro/coriander, fennel and cumin. Three different types of carrots are depicted, and the states of them that the root can be cooked. The plant appears to have been introduced into Spain by the Moors in the 8th century, in the 10th century, in worldwide locations like West Asia and Europe, the roots were purple. The modern carrot originated in Afghanistan at about this time, the Jewish scholar Simeon Seth describes both red and yellow carrots in the 11th century.
The 12th-century Arab-Andalusian agriculturist, Ibn al-Awwam, mentions roots of these colours, cultivated carrots appeared in China in the 14th century, and in Japan in the 18th century. Orange-coloured carrots appeared in the Netherlands in the 17th century, which has been related to the fact that the Dutch flag at the time, the Princes Flag, included orange. These, the carrots, were intended by the English antiquary John Aubrey when he noted in his memoranda
Pectobacterium carotovorum is a bacterium of the family Enterobacteriaceae, it used to be a member of the genus Erwinia. The species is a plant pathogen with a diverse host range and it produces pectolytic enzymes that hydrolyze pectin between individual plant cells. This causes the cells to separate, a disease plant pathologists term bacterial soft rot, specifically, it causes beet vascular necrosis and blackleg of potato and other vegetables, as well as slime flux on many different tree species. This bacterium is a plant pathogen with a wide host range. It is an economically important pathogen in terms of postharvest losses. Decay caused by P. carotovora is often referred to as bacterial soft rot though this may be caused by other bacteria, most plants or plant parts can resist invasion by the bacteria, unless some type of wound is present. High humidity and temperatures around 30°C favor development of decay, mutants can be produced which are less virulent. Virulence factors include, pectinases and proteases, xylanases, Waleron, M, Waleron, K, Lojkowska, E.
Characterization of Pectobacterium carotovorum subsp. Odoriferum causing soft rot of stored vegetables, type strain of Pectobacterium carotovorum at BacDive - the Bacterial Diversity Metadatabase
National Center for Biotechnology Information
The National Center for Biotechnology Information is part of the United States National Library of Medicine, a branch of the National Institutes of Health. The NCBI is located in Bethesda and was founded in 1988 through legislation sponsored by Senator Claude Pepper, the NCBI houses a series of databases relevant to biotechnology and biomedicine and is an important resource for bioinformatics tools and services. Major databases include GenBank for DNA sequences and PubMed, a database for the biomedical literature. Other databases include the NCBI Epigenomics database, all these databases are available online through the Entrez search engine. NCBI is directed by David Lipman, one of the authors of the BLAST sequence alignment program. He leads a research program, including groups led by Stephen Altschul, David Landsman, Eugene Koonin, John Wilbur, Teresa Przytycka. NCBI is listed in the Registry of Research Data Repositories re3data. org, NCBI has had responsibility for making available the GenBank DNA sequence database since 1992.
GenBank coordinates with individual laboratories and other databases such as those of the European Molecular Biology Laboratory. Since 1992, NCBI has grown to other databases in addition to GenBank. The NCBI assigns a unique identifier to each species of organism, the NCBI has software tools that are available by WWW browsing or by FTP. For example, BLAST is a sequence similarity searching program, BLAST can do sequence comparisons against the GenBank DNA database in less than 15 seconds. RAG2/IL2RG The NCBI Bookshelf is a collection of freely accessible, some of the books are online versions of previously published books, while others, such as Coffee Break, are written and edited by NCBI staff. BLAST is a used for calculating sequence similarity between biological sequences such as nucleotide sequences of DNA and amino acid sequences of proteins. BLAST is a tool for finding sequences similar to the query sequence within the same organism or in different organisms. It searches the query sequence on NCBI databases and servers and post the results back to the browser in chosen format.
Input sequences to the BLAST are mostly in FASTA or Genbank format while output could be delivered in variety of such as HTML, XML formatting. HTML is the output format for NCBIs web-page. Entrez is both indexing and retrieval system having data from sources for biomedical research
Tubers are enlarged structures in some plant species used as storage organs for nutrients. They are used for the plants perennation, to energy and nutrients for regrowth during the next growing season. Stem tubers form from thickened rhizomes or stolons, common plant species with stem tubers include potato and yam. Some sources treat modified lateral roots under the definition, these are encountered in sweet potato, the term originates from Latin tuber, meaning lump, swelling. Some sources define the term tuber to mean only structures derived from stems, a stem tuber forms from thickened rhizomes or stolons. The top sides of the tuber produce shoots that grow into stems and leaves. They tend to form at the sides of the parent plant and are most often located near the soil surface, the underground stem tuber is normally a short-lived storage and regenerative organ developing from a shoot that branches off a mature plant. The offsprings or new tubers are attached to a parent tuber or form at the end of a hypogeogenous rhizome, some plants form smaller tubers and/or tubercules which act like seeds, producing small plants that resemble seedlings.
Stem tubers generally start off as enlargements of the section of a seedling. Tuberous begonia and Cyclamen are commonly grown stem tubers, mignonette vine produces aerial stem tubers on 12-to-25-foot-tall vines, the tubers fall to the ground and grow. Enlarged stolons thicken to develop into storage organs, the tuber has all the parts of a normal stem, including nodes and internodes. The nodes are the eyes and each has a leaf scar, the nodes or eyes are arranged around the tuber in a spiral fashion beginning on the end opposite the attachment point to the stolon. The terminal bud is produced at the farthest point away from the stolon attachment, internally, a tuber is filled with starch stored in enlarged parenchyma like cells. The inside of a tuber has the cell structures of any stem, including a pith, vascular zones. The tuber is produced in one growing season and used to perennate the plant, as the main shoot develops from the tuber, the base of the shoot close to the tuber produces adventitious roots and lateral buds on the shoot.
The shoot produces stolons that are long etiolated stems, the stolon elongates during long days with the presence of high auxins levels that prevent root growth off of the stolon. Before new tuber formation begins, the stolon must be a certain age, the enzyme lipoxygenase makes a hormone, jasmonic acid, which is involved in the control of potato tuber development. The stolons are easily recognized when potato plants are grown from seeds, as the plants grow, stolons are produced around the soil surface from the nodes
Electrostatics is a branch of physics that deals with the phenomena and properties of stationary or slow-moving electric charges. Since classical physics, it has known that some materials such as amber attract lightweight particles after rubbing. The Greek word for amber, ήλεκτρον, or electron, was the source of the word electricity, Electrostatic phenomena arise from the forces that electric charges exert on each other. Such forces are described by Coulombs law, Electrostatics involves the buildup of charge on the surface of objects due to contact with other surfaces. This is because the charges that transfer are trapped there for a long enough for their effects to be observed. We begin with the magnitude of the force between two point charges q and Q. It is convenient to one of these charges, q, as a test charge. As we develop the theory, more source charges will be added.854187817 ×10 −12 C2 N −1 m −2, the SI units of ε0 are equivalently A2s4 kg−1m−3 or C2N−1m−2 or F m−1. Coulombs constant is, k e ≈14 π ε0 ≈8.987551787 ×109 N m 2 C −2. A single proton has a charge of e, and the electron has a charge of −e and these physical constants are currently defined so that ε0 and k0 are exactly defined, and e is a measured quantity.
Electric field lines are useful for visualizing the electric field, field lines begin on positive charge and terminate on negative charge. Electric field lines are parallel to the direction of the field. The electric field, E →, is a field that can be defined everywhere. It is convenient to place a hypothetical test charge at a point, by Coulombs Law, this test charge will experience a force that can be used to define the electric field as follow F → = q E →. For a single point charge at the origin, the magnitude of electric field is E = k e Q / R2. The fact that the force can be calculated by summing all the contributions due to individual source particles is an example of the superposition principle. If the charge is distributed over a surface or along a line, the Divergence Theorem allows Gausss Law to be written in differential form, ∇ → ⋅ E → = ρ ε0. Where ∇ → ⋅ is the divergence operator, the definition of electrostatic potential, combined with the differential form of Gausss law, provides a relationship between the potential Φ and the charge density ρ, ∇2 ϕ = − ρ ε0