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SUMMARY / RELATED TOPICS

Facilitated diffusion

Facilitated diffusion is the process of spontaneous passive transport of molecules or ions across a biological membrane via specific transmembrane integral proteins. Being passive, facilitated transport does not directly require chemical energy from ATP hydrolysis in the transport step itself. Facilitated diffusion is different from simple diffusion in several ways; the transport relies on molecular binding between the cargo and the membrane-embedded channel or carrier protein. The rate of facilitated diffusion is saturable with respect to the concentration difference between the two phases; the temperature dependence of facilitated transport is different due to the presence of an activated binding event, as compared to free diffusion where the dependence on temperature is mild. Polar molecules and large ions dissolved in water cannot diffuse across the plasma membrane due to the hydrophobic nature of the fatty acid tails of the phospholipids that make up the lipid bilayer. Only small, non-polar molecules, such as oxygen and carbon dioxide, can diffuse across the membrane.

Hence, no nonpolar molecules are transported by proteins in the form of transmembrane channels. These channels are gated, meaning that they open and close, thus deregulate the flow of ions or small polar molecules across membranes, sometimes against the osmotic gradient. Larger molecules are transported by transmembrane carrier proteins, such as permeases, that change their conformation as the molecules are carried across. Non-polar molecules, such as retinol or lipids, are poorly soluble in water, they are transported through aqueous compartments of cells or through extracellular space by water-soluble carriers. The metabolites are not altered. Only permease changes its shape; the form of transport through a cell membrane in which a metabolite is modified is called group translocation transportation. Glucose, sodium ions, chloride ions are just a few examples of molecules and ions that must efficiently cross the plasma membrane but to which the lipid bilayer of the membrane is impermeable, their transport must therefore be "facilitated" by proteins that span the membrane and provide an alternative route or bypass mechanism.

Various attempts have been made by engineers to mimic the process of facilitated transport in synthetic membranes for use in industrial-scale gas and liquid separations, but these have met with limited success to date, most for reasons related to poor carrier stability and/or dissociation of the carrier from the passive transport. In living organisms, the main physical and biochemical processes that are required for survival are regulated by diffusion. Facilitated diffusion is one form of diffusion and it is important in several metabolic processes of living cells. One vital role of facilitated diffusion is that it is the main mechanism behind the binding of Transcription Factors to designated target sites on the DNA molecule; the in vitro model, a well known method of facilitated diffusion, that takes place outside of a living cell, explains the 3-dimensional pattern of diffusion in the cytosol and the 1-dimensional diffusion along the DNA contour. After carrying out extensive research on processes occurring out of the cell, this mechanism was accepted but there was a need to verify that this mechanism could take place in vivo or inside of living cells.

Bauer & Metzler therefore carried out an experiment using a bacterial genome in which they investigated the average time for TF – DNA binding to occur. After analyzing the process for the time it takes for TF's to diffuse across the contour and cytoplasm of the bacteria's DNA, it was concluded that in vitro and in vivo are similar in that the association and dissociation rates of TF's to and from the DNA are similar in both. On the DNA contour, the motion is slower and target sites are easy to localize while in the cytoplasm, the motion is faster but the TF's are not sensitive to their targets and so binding is restricted. Single-molecule imaging is an imaging technique which provides an ideal resolution necessary for the study of the Transcription factor binding mechanism in living cells. In prokaryotic bacteria cells such as E. coli, facilitated diffusion is required in order for regulatory proteins to locate and bind to target sites on DNA base pairs. There are 2 main steps involved: the protein binds to a non-specific site on the DNA and it diffuses along the DNA chain until it locates a target site, a process referred to as sliding.

According to Brackley et al. during the process of protein sliding, the protein searches the entire length of the DNA chain using 3-D and 1-D diffusion patterns. During 3-D diffusion, the high incidence of Crowder proteins creates an osmotic pressure which brings searcher proteins closer to the DNA to increase their attraction and enable them to bind, as well as steric effect which exclude the Crowder proteins from this region. Blocker proteins participate in 1-D diffusion only i.e. bind to and diffuse along the DNA contour and not in the cytosol. The in vivo model mentioned above explains 3-D and 1-D diffusion along the DNA strand and the binding of proteins to target sites on the chain. Just like prokaryotic cells, in eukaryotes, facilitated diffusion occurs in the nucleoplasm on chromatin filaments, accounted for by

Archelaus Smith

Archelaus Smith, was a tanner and early settler of Barrington, Nova Scotia. He was born in Chatham, Province of Massachusetts to parents Deacon Stephen Smith and Bathsheba Smith, he was christened in the Congregational Church, Chatham on 23 Apr 1734. At eighteen years of age he married Elizabeth Nickerson, daughter of William Nickerson and Sarah Nickerson, in Chatham, in a ceremony performed by the Reverend Stephen Emerey, they had eight children. In the spring of 1760 Smith began planning to move his family from their home in Chatham to a new home in Barrington, Nova Scotia, he was to be one of the earliest settlers in the area, along with Solomon Smith, Jonathan Smith, Thomas Crowell. He spent the summer of 1760 fishing, during that time, determined native hostility in the Barrington area was too threatening, so he changed his mind about moving. However, his wife Elizabeth was unaware of his change of heart, took it upon herself to travel to Barrington with her family before her husband returned to Chatham.

It is possible that they crossed paths, but he was delayed in returning to Barrington. When he got there, he found his family being cared for by friendly natives, the same people he had feared. Smith was one of the original proprietors in the area, settling at Barrington Head in the fall of 1760. In fact, the first three houses at Centreville were called "the Housen", belonged to Archelaus Smith, Simeon Gardner, Jonathan Covell. "Housen" was Anglo-Saxon for houses. Smith's home was nearly opposite the old meeting house. In 1773 he moved to Cape Sable Island, where he and his family occupied all the land from Northeast Point to West Head, he held a tract of land at Lower Clark's Harbour, Cape Sable Island, a large part of Hawk Point, a great meadow in the centre of the island. He took over land, forfeited and abandoned by Joseph Worth, built a home near the shore, a little north of where the Centreville Baptist Church would stand. Around 1776 he moved to a house near the shore on Cape Sable Island, near the spot where just before 1981 Job Kenney would build the house that stands today.

It is a short distance from the Centreville Baptist Church. Smith had a fair education, was respected by other settlers, he was known as a "good, easy, patient man", was chosen over several years to be clerk of the proprietors, as well as a community magistrate and a surveyor. By trade he was a shoemaker, using lime made from mussel shells to cure leather, he was religious, belonging to the Presbyterian church, no food was cooked in his house on Sundays. Before a minister came to the island he conducted prayers for the community, when necessary, buried the dead. Smith died 3 April 1821 in Nova Scotia, he is buried in the Centreville Cemetery, but his grave is unmarked, so in 1998 a stone in honour of Smith and his wife was erected there. In addition, a museum on Cape Sable Island has been established in his memory, containing historical artifacts and genealogical data of area families. Http://www.nickersonassoc.org/ Archelaus Smith museum

W (New York City Subway service)

The W Broadway Local is a rapid transit service of the New York City Subway's B Division. Its route emblem, or "bullet", is colored yellow; the W operates weekdays only except late nights between Ditmars Boulevard in Astoria and Whitehall Street in Lower Manhattan, making local stops along its entire route. The W is internally staffed and scheduled as part of the N. Introduced on July 22, 2001, the W ran at all times on the BMT West End Line and BMT Fourth Avenue Line in Brooklyn to Coney Island–Stillwell Avenue, it was truncated in 2004 to its current service pattern until June 25, 2010, when it was eliminated due to the Metropolitan Transportation Authority's financial crisis. The route was reinstated on November 7, 2016, using its original emblem and 2004–2010 routing, as part of the updated service pattern related to the opening of the Second Avenue Subway; the W was conceived as an extra Broadway Line local service running on the Astoria and Broadway lines to Whitehall Street in Manhattan.

This service was a variant of the N route, which in the 1970s and 1980s ran express on the Broadway Line between Forest Hills–71st Avenue in Queens and Coney Island–Stillwell Avenue in Brooklyn. At the time, some trains ran local on Broadway and only traveled between Forest Hills and Whitehall Street. However, reconstruction of the Manhattan Bridge's subway tracks between 1986 and 2004 forced the N, which ran express on the Broadway Line and via the bridge, to run local via the Montague Street Tunnel; this service change precluded W local service from running as envisioned. The W bullet appeared on roll signs as a yellow diamond bullet, but on the R68s and R68As, round bullet signs were installed; the W appeared on the digital signs of the R44s and R46s with any route and destination combination that could be used for the Broadway Line. The W label was first used in 2001, when the two tracks on the Manhattan Bridge's northern side, which connected to the IND Sixth Avenue Line, were closed for repairs.

This required the suspension of Sixth Avenue B service south of 34th Street–Herald Square as it used those tracks to travel to and from Brooklyn. The W service replaced the B on the BMT West End Line and BMT Fourth Avenue Line in Brooklyn, ran on the BMT Broadway Line in Manhattan and BMT Astoria Line in Queens, it replicated the route of the Brooklyn-Manhattan Transit Corporation's old 3 route named the T, that operated from 1916 until 1967, when the B replaced it. The W replicated the split in B service from 1986 to 1988, when the bridge's north tracks were first closed, although both halves of the route were labeled B. W service began July 22, 2001 in conjunction with the reopening of the south tracks of the Manhattan Bridge and the closure of the bridge's north tracks. Service began operating between Coney Island and Astoria-Ditmars Boulevard, Queens via the West End Local and Fourth Avenue Express in Brooklyn; the W ran express on the Astoria Line during rush hours in the peak direction between 6 a.m. and 9 p.m. and local at all other times.

Trains ran express to Manhattan between 6 a.m. and 1 p.m. and to Astoria from 1 p.m. to 9 p.m.. Evening service terminated at 57th Street–Seventh Avenue in Manhattan, while late night and weekend evening service operated as a shuttle within Brooklyn only, terminating at 36th Street during late nights and Atlantic Avenue–Pacific Street on weekends. After September 11, 2001, all Broadway Line service in Lower Manhattan was suspended due to extensive damage caused by the Collapse of the World Trade Center; as a result, the entire N route was suspended, W trains ran at all times between Ditmars Boulevard and Coney Island. It made. During late nights, it ran in two sections: between Ditmars Boulevard and 34th Street, skipping 49th Street in the northbound direction, in Brooklyn between 36th Street and Coney Island. Normal service on both routes resumed on October 28, 2001; the Astoria express service was discontinued on January 15, 2002. Because it was unpopular among Astoria residents; this change was approved by the MTA Board in December 2001.

Express service was implemented on the Astoria Line in order to improve operations at the Ditmars Boulevard terminal, because 43% of the line's riders boarded at express stations. Instead, the change yielded no operational benefits, made local N trains overcrowded, express W trains underutilized. N trains carried 1.9 times as many passengers as W trains in the morning, 2.6 times as many in the evening. W express. After normal service resumed in October 2001, local W service was kept until November 19 on a trial basis. Analysis of the operating pattern found that the terminal could handle the all-local service pattern and that the ridership split between the N and W was more balanced. Around that time, evening service was extended from 57th Street to Astoria. On September 8, 2002, W service was extended to Astoria during late nights and weekends, running local via the Fourth Avenue and Broadway Lines and Montague Street Tunnel; this was because ongoing reconstruction of the Coney Island–Stillwell Avenue terminal left the W as the only train serving it.

This change gave the West End Line late-night service to Manhattan for the first time. When the Manhattan Bridge's north tra

PBA Bowling Tour: 1975 Season

This is a recap of the 1975 season for the Professional Bowlers Association Tour. It was the tour's 17th season, consisted of 34 events. Earl Anthony became the first PBA player to win seven titles in a season since Dick Weber, while gaining an unprecedented "three-peat" in the Brunswick PBA National Championship; as he did in 1974, Anthony won the player vote for the PBA Player of the Year award. In another historic "first," Anthony earned $107,585 in 1975 to become the first bowler to collect over $100,000 in a single season. Steve Neff made his second PBA Tour win count, capturing the BPAA U. S. Open, while Dave Davis collected his second career Firestone Tournament of Champions trophy. Don Johnson won his 24th career PBA Tour title in the Tucson Open, which at the time tied him with Dick Weber for the most Tour wins. 1975 Season Schedule

Solar System

The Solar System is the gravitationally bound system of the Sun and the objects that orbit it, either directly or indirectly. Of the objects that orbit the Sun directly, the largest are the eight planets, with the remainder being smaller objects, the dwarf planets and small Solar System bodies. Of the objects that orbit the Sun indirectly—the moons—two are larger than the smallest planet, Mercury; the Solar System formed 4.6 billion years ago from the gravitational collapse of a giant interstellar molecular cloud. The vast majority of the system's mass is in the Sun, with the majority of the remaining mass contained in Jupiter; the four smaller inner planets, Venus and Mars, are terrestrial planets, being composed of rock and metal. The four outer planets are giant planets, being more massive than the terrestrials; the two largest and Saturn, are gas giants, being composed of hydrogen and helium. All eight planets have circular orbits that lie within a nearly flat disc called the ecliptic; the Solar System contains smaller objects.

The asteroid belt, which lies between the orbits of Mars and Jupiter contains objects composed, like the terrestrial planets, of rock and metal. Beyond Neptune's orbit lie the Kuiper belt and scattered disc, which are populations of trans-Neptunian objects composed of ices, beyond them a newly discovered population of sednoids. Within these populations, some objects are large enough to have rounded under their own gravity, though there is considerable debate as to how many there will prove to be; such objects are categorized as dwarf planets. Identified or accepted dwarf planets include the asteroid Ceres and the trans-Neptunian objects Pluto and Eris. In addition to these two regions, various other small-body populations, including comets and interplanetary dust clouds travel between regions. Six of the planets, the six largest possible dwarf planets, many of the smaller bodies are orbited by natural satellites termed "moons" after the Moon; each of the outer planets is encircled by planetary rings of dust and other small objects.

The solar wind, a stream of charged particles flowing outwards from the Sun, creates a bubble-like region in the interstellar medium known as the heliosphere. The heliopause is the point at which pressure from the solar wind is equal to the opposing pressure of the interstellar medium; the Oort cloud, thought to be the source for long-period comets, may exist at a distance a thousand times further than the heliosphere. The Solar System is located in the Orion Arm, 26,000 light-years from the center of the Milky Way galaxy. For most of history, humanity did not understand the concept of the Solar System. Most people up to the Late Middle Ages–Renaissance believed Earth to be stationary at the centre of the universe and categorically different from the divine or ethereal objects that moved through the sky. Although the Greek philosopher Aristarchus of Samos had speculated on a heliocentric reordering of the cosmos, Nicolaus Copernicus was the first to develop a mathematically predictive heliocentric system.

In the 17th century, Galileo discovered that the Sun was marked with sunspots, that Jupiter had four satellites in orbit around it. Christiaan Huygens followed on from Galileo's discoveries by discovering Saturn's moon Titan and the shape of the rings of Saturn. Edmond Halley realised in 1705 that repeated sightings of a comet were recording the same object, returning once every 75–76 years; this was the first evidence that anything other than the planets orbited the Sun. Around this time, the term "Solar System" first appeared in English. In 1838, Friedrich Bessel measured a stellar parallax, an apparent shift in the position of a star created by Earth's motion around the Sun, providing the first direct, experimental proof of heliocentrism. Improvements in observational astronomy and the use of unmanned spacecraft have since enabled the detailed investigation of other bodies orbiting the Sun; the principal component of the Solar System is the Sun, a G2 main-sequence star that contains 99.86% of the system's known mass and dominates it gravitationally.

The Sun's four largest orbiting bodies, the giant planets, account for 99% of the remaining mass, with Jupiter and Saturn together comprising more than 90%. The remaining objects of the Solar System together comprise less than 0.002% of the Solar System's total mass. Most large objects in orbit around the Sun lie near the plane of Earth's orbit, known as the ecliptic; the planets are close to the ecliptic, whereas comets and Kuiper belt objects are at greater angles to it. As a result of the formation of the Solar System planets, most other objects, orbit the Sun in the same direction that the Sun is rotating. There are exceptions, such as Halley's Comet. Most of the larger moons orbit their planets in this prograde direction and most larger objects rotate themselves in the same direction; the overall structure of the charted regions of the Solar System consists of the Sun, four small inner planets surrounded by a belt of rocky asteroids, four giant planets surrounded by the Kuiper belt of icy objects.

Astronomers sometimes informally divide this structure into separate

Unskinny Bop

"Unskinny Bop" is a song by American glam metal band Poison, released as the first single from their 1990 Flesh & Blood album. The song peaked at number 3 on the US Billboard Hot 100, number 5 on the Mainstream rock charts, number 15 in the UK and #7 on the Australian charts; this made it the band's second highest success, after "Every Rose Has Its Thorn." The music video for the song has Bret Michaels dancing with a couple of animated neon cowgirls next to him. The meaning of "Unskinny Bop" has always been shrouded in obscurity. C. C. DeVille confessed that the phrase "unskinny bop" has no particular meaning, he invented it as a temporary measure while writing the song, before vocalist Bret Michaels had begun working on the lyrics. The phrase was used on the basis; the song was played to producer Bruce Fairbairn, who stated that, although he did not know what an "unskinny bop" was, the phrase was perfect. It has always been a popular song for dancers at Gentlemen's Clubs since its release. Lyrics of this song at MetroLyrics