Opryland USA (later called Opryland Theme park and colloquially referred to simply as Opryland) was an amusement park in suburban Nashville, Tennessee. It operated seasonally (generally March to October) from 1972 to 1997, and for a special Christmas-themed engagement every December from 1993 to 1997. During the late 1980s, nearly 2.5 million people visited the park annually. Billed as the "Home of American Music," Opryland USA featured a large number of musical shows along with typical amusement park rides such as roller coasters, carousels, and the like.
History
1970s
The genesis for a theme park in Nashville was the desire for a new, permanent, larger and more modern home for the long-running Grand Ole Opry radio program. The Ryman Auditorium, its home since 1943, was beginning to suffer from disrepair as the downtown neighborhood around it was falling victim to increasing urban decay. Despite these shortcomings, the show's popularity was increasing and its weekly crowds were outgrowing the 3,000-seat venue. Organizers were seeking to build a new air-conditioned venue with a greater capacity and ample parking in a then-rural area of town, providing visitors a safer and more enjoyable experience.[1]
WSM, Inc. (a subsidiary of the National Life and Accident Insurance Company, later NLT Corporation), the operator of WSM-AM-FM-TV and the Opry, purchased a large tract of riverside land (Rudy's Farm) owned by a local sausage manufacturer in the Pennington Bend area of Nashville, adjacent to the newly constructed Briley Parkway. The new Opry venue was to be the centerpiece of a grand entertainment complex at that location, which would come to include the theme park and a large hotel/convention center.
The theme park opened to the public on May 27, 1972,[2] well ahead of the Grand Ole Opry House, which debuted nearly two years later, on March 16, 1974. The park was named for WSM disc jockey Grant Turner's early morning show, "Opryland USA", itself a nod to the stars of the Grand Ole Opry. However, despite the obvious connection to country music, the park's overall theme was American music in general; there were jazz, gospel, bluegrass, pop, and rock and roll-themed attractions and shows in addition to country. Opryland's focus was more on its musical productions rather than its rides and other attractions. As such, it was billed as a "showpark", and not an "amusement park" or "theme park" in its early days. Major thrill rides at the park's opening included the "Timber Topper" (later renamed "Rock 'n Roller Coaster") roller coaster and "Flume Zoom" (later renamed "Dulcimer Splash") log flume.
In the fourth season in 1975, Opryland expanded for the first time. The "State Fair" area was constructed on land formerly occupied by the park's buffalo exhibit. The new expansion featured a large selection of carnival games, as well as the Wabash Cannonball roller coaster, Country Bumpkin Bump Cars, and Tennessee Waltz swings. However, shortly before opening for the season, the park fell victim to a large flood of the Cumberland River that covered most of the park and was as deep as sixteen feet in some locations. The park's opening was delayed by a month and several animals in the petting zoo were killed by the floodwaters.
Opryland became extremely successful during the mid-1970s, and by the 1977 season the park was drawing nearly 2 million guests annually, the preponderance of which were from Tennessee and adjoining states. The park also drew upon the continued appeal of the Opry show itself to Southern and Midwestern country music fans elsewhere, who often brought their families for a several-days' vacation in Nashville. The nearest theme parks comparable to Opryland were four to six hours away, in places such as Cincinnati (Kings Island), St. Louis (Six Flags over Mid-America), and Atlanta (Six Flags Over Georgia).  Attendance continued to climb into the 1980s.
In 1977, Opryland Hotel (now called Gaylord Opryland Resort & Convention Center), a large resort-style hotel, was built next door to the park, and has expanded several times to become the largest hotel in the world not attached to a casino.[3][4][5]
In 1979, Opryland added the Roy Acuff Theater, named after the beloved traditional country singer and pillar of the Opry, next door to the Grand Ole Opry House in the Plaza area. It was primarily used for the theme park's premier musical production. Because the theater was placed outside the park gates, tickets to the theme park were not required to attend shows at the Acuff. However, shows at this venue usually required a separately-purchased ticket. This also allowed the general public to attend shows at the Acuff without having to pay for park admission, like the Opry itself.
Ownership change
Beginning in 1980, Houston-based insurer American General began purchasing blocks of NLT stock, eventually becoming NLT's largest shareholder and setting the stage for an outright takeover. However, American General was not interested in NLT's non-insurance businesses and opted to sell off the WSM division, which included WSM-AM-FM-TV, The Nashville Network, the Grand Ole Opry, the then-decrepit Ryman Auditorium, Opryland Hotel, and Opryland USA. Unable to acquire television and radio assets due to FCC ownership restrictions of the time, American General influenced NLT to sell WSM-TV to Gillett Broadcasting (operated by George N. Gillett Jr.), which bought the station on November 3, 1981 and changed the station's call sign to WSMV (officially modified to WSMV-TV on July 15, 1982[6]).
By 1982, the takeover was complete and American General began approaching companies such as MCA, Marriott Corporation and Anheuser-Busch about a possible sale of the remainder of WSM, Inc. While many of the companies showed interest in one of the assets, such as the theme park alone or the radio station, none was willing to buy the entire complex. American General began to feel that the only way to sell WSM, Inc. would be to split it up into separate entities.
Suddenly, Gaylord Broadcasting Company of Oklahoma City stepped in and purchased the entire package in September 1983 for US$250,000,000(equivalent to $628,884,063 in 2018).[7] After the purchase, the company's name was changed to Gaylord Entertainment Company. Ed Gaylord, the then-controlling figure of Gaylord Entertainment, was a huge fan of the Opry and weighed in on the decision to purchase Opryland.
Also included in Gaylord's acquisition of the Opryland assets was WSM's fledgling cable network, The Nashville Network (TNN) and its production arm, Opryland Productions. TNN became a television network dedicated entirely to country music. For years, its offices and production facilities were located on-site at Opryland, and a nightly variety show (originally Nashville Now, later Music City Tonight and Prime Time Country) was broadcast live from the Gaslight Theatre inside the park itself. The theme park was often featured on the network as a concert venue for country music stars.
1980s – 1990s
In 1982, Opryland expanded its footprint for the second and final time. The new area, entitled "Grizzly Country", was built on the extreme north end of the park to house the Grizzly River Rampage, a river rafting ride. The ride was originally promoted by band called the Grizzly River Boys, later known as the Tennessee River Boys, who were originally intended to promote the park through a one-time television special, but became popular enough that they were a permanent attraction in the park for several years. The band's membership originally included Ty Herndon, and after several personnel changes, grew to become the band Diamond Rio.
In 1984, Opryland added a third roller coaster, "The Screamin' Delta Demon" (an Intamin bobsled roller coaster), in the New Orleans area of the park. This project also included adding a second (albeit subtle) park gate adjacent to the parking lot.
In the mid-1980s, "Trickets" (three-day admission tickets for one price) were introduced and large numbers of season passes were sold to residents of the Nashville area.
In the late 1980s and early 1990s, two new competitors to Opryland would emerge: Kentucky Kingdom in Louisville, Kentucky, and Dollywood in Pigeon Forge, Tennessee (which had recently been converted and expanded from its previous incarnation as "Silver Dollar City"). These two parks grew into regional destinations, contributing in part to a decline in Opryland attendance. Partially in response to the competition, and to entice out-of-town guests to come, package deals including rooms at the hotel, tickets to Opryland, and admission to the Grand Ole Opry were developed and marketed throughout the region.
Annual changes were made to the park to continue to attract local Nashvillians as well as out-of-town visitors. Large attractions such as the General Jackson Showboat, new roller coasters, and water rides were installed on a biennial basis until 1989, with the opening of the "Chaos" roller coaster. The next (and final) large attraction to open would be "The Hangman" roller coaster in 1995.
In 1992, the Chevrolet-Geo Celebrity Theater (renamed Chevrolet Theater in 1997, following General Motors' shuttering of the Geo brand) was constructed on the site of the former Jukebox and Flip-Side Theaters. With the construction of the park's new flagship venue, Opryland began attracting top country music acts for nightly concerts, included in the price of park admission. In 1994, Opryland began upcharging for the concerts and added two venues (Theater By The Lake and the Roy Acuff Theater) to the series, billing it as "Nashville On Stage". As part of this, the Chevrolet-Geo Theater and Theater By The Lake venues were expanded and partially enclosed. Alabama, George Jones, Tammy Wynette, Tanya Tucker, and The Oak Ridge Boys took up residency at the park during the summer of 1994, occupying the Chevrolet-Geo Celebrity Theater and Theater By The Lake, while the conventional concert series, featuring traveling artists, moved to the Roy Acuff Theater. During the day, the Roy Acuff Theater also hosted a live version of "Hee Haw" based on the long-running TV series. After lackluster ticket sales, the multi-venue series was significantly scaled back after 1994. By Opryland's final season in 1997, only the Chevrolet Theater was hosting concerts.
During the summer of 1993, the popular Mark Goodson game show Family Feud traveled to Opryland and taped  at the Chevrolet-Geo Celebrity Theater, which opened the show's sixth and final season with Ray Combs as host. These syndicated episodes began airing in September and featured some of country music's brightest stars including Porter Wagoner, Boxcar Willie, Charley Pride, Brenda Lee, the Mandrells, and the Statler Brothers, as well as at least one week of regular Nashville families playing against each other. As of 2017, it remains the only time in the history of the long-running series that episodes have been taped outside of its home studio.
Also, beginning in the early 1990s and continuing through its final season, as a nod to TNN's NASCAR coverage, as well as Opryland's official designation with NASCAR, the annual "TNN Salute to Motorsports" event would take place over a weeklong period. This included numerous motorsports exhibits as well as meet-and-greets with racing personalities.
In 1994, Gaylord Entertainment invested heavily in the renaissance of the entertainment district in downtown Nashville. The company converted an old Second Avenue building into the Wildhorse Saloon, renovated and reopened the Ryman Auditorium as a premier concert and theatre venue, and began to provide water taxi service along the Cumberland River between the docks adjacent to the amusement park and a dock downtown. As part of this, the amusement park's official name was changed to "Opryland Themepark". The "Opryland USA" name was then designated as the destination's name, to encompass all of Gaylord Entertainment's Nashville properties.
In September 1995 and September 1996, the Grizzly River Rampage was used as a course for the NationsBank Whitewater Championships, which (in 1995 alone) served as a qualifier for the 1996 Summer Olympics in Atlanta. Following those events (as well as 1997), the course was drained and a temporary Halloween attraction—"Quarantine", tied into the storyline of the neighboring indoor roller coaster "Chaos"—was constructed in its bed.
In 1996, a third park gate was added near "Chaos", which allowed pedestrian traffic between Opryland Hotel and Opryland Themepark for the very first time. Previously, hotel guests wishing to visit the amusement park would be shuttled between the two on buses.
Shuttering and demolition
From the beginning, Opryland was severely handicapped by its location. The park was located on a roughly-triangular tract of land with the Cumberland River on one side, and Briley Parkway on another. Opryland Hotel was built in 1977 on the third and shortest leg of the triangle. This not only exposed the park to occasional flooding, but hampered its ability to expand to include new attractions as consumer preferences changed. Opryland was forced to remove older attractions to add new ones, as was the case with the Raft Ride in 1986 for the Old Mill Scream, and the Tin Lizzies in 1994 for The Hangman.  In 1993, Gaylord Entertainment embarked on the largest-ever construction project in Nashville's history at the time: the Delta. This project, which opened in 1996, added an enormous new atrium, over 1,000 guestrooms, and a new convention complex to Opryland Hotel. By this time, Opryland had grown to 200 acres (0.81km2) in size.  However, the Delta project tied up all of the remaining land contiguous to the park, leaving it with nowhere else to grow.
In addition, Nashville's climate made year-round operations almost impossible; seasons were largely limited to weekends in the late fall and early spring and daily in the summer. Seasonal workers became hard to find, and Gaylord found itself with a labor shortage. Attendance plateaued throughout the first half of the 1990s. By 1997, Gaylord management, in a move toward refocusing on its core hospitality businesses, decided that the Opryland property would no longer make a rate of return equal to that desired for its properties and was unlikely ever to return to doing so. Management decided the amusement park should be replaced by a property which made year-round usage of the site.
Rumors began to surface during the summer of 1997 that Gaylord was considering selling or demolishing the theme park. The decision to close the park and replace it with a shopping mall named Opry Mills was made public that November, about a week after the end of the park's regular season.[8]
The 1997 "Christmas in the Park" season was billed as a "last chance" for Nashvillians to see Opryland, though only a small portion of the park was open for the season, and many of the larger attractions were already being dismantled. The park closed permanently on December 31, 1997. In early 1998, the park's remaining merchandise, signage and fixtures were offered to the public in a parking lot tent sale.
All five roller coasters and many other large attractions were sold to Premier Parks. The Hangman was relocated immediately to Marine World in Northern California, where it became known as Kong. The remainder of the attractions were moved to a field near Indianapolis, Indiana, where the company was prepared to revive the dormant Old Indiana Fun Park. Those plans were soon scrapped when Premier Parks purchased Six Flags and adopted its corporate name. The pieces of Opryland's attractions sat rusting in the Indiana field until 2002, when the site was sold. By 2006, the site was cleared, and it is now farmland. Some of the flat rides were sold for scrap metal, while the fate of many of the larger attractions remains unknown. However, in 2003, The Rock n' Roller Coaster was reassembled at Six Flags Great Escape in Queensbury, New York, where it became known as Canyon Blaster. One of the Wabash Cannonball's cars also appeared at a park in Belgium as part of a Halloween display.
The Opryland Themepark site was cleared and paved into a parking lot for Opry Mills and the Grand Ole Opry House by July 1999, while construction of the mall took place primarily on the site of the themepark's parking lot.
Post-demolition

Opry Mills opened May 12, 2000, under the ownership of Mills Corporation (later acquired by Simon Property Group). Gaylord Entertainment initially had a minority stake in the new shopping center, but later divested it. When the arrangements for the future of the Opryland property were made public in 1997, Gaylord announced its intentions to construct a new entry plaza for the Grand Ole Opry House with shops and restaurants, as well as a public marina and entertainment complex at Cumberland Landing (the General Jackson's port). However, these plans were abandoned as Gaylord focused less on entertainment and more on its hospitality assets.
The long low concrete levee wall which once separated the park's New Orleans, Riverside and State Fair areas from the Cumberland River is still a part of the mall grounds, and visitors who enter the mall property from the McGavock Pike entrance can still view remnants of the graded railroad embankment which once supported the tracks of the park's short-line railroad.
The Southern Living Cumberland River Cottage became a training center for hotel employees (Gaylord University), and was moved intact to the former location of Chaos until being torn down in 2010. The large administration building that briefly sat outside the park gates became the offices of the General Jackson and Music City Queen riverboats, and was moved intact to a location near the Cumberland Landing docks.
Much of the Opry Plaza area remained untouched and open for business. The Grand Ole Opry House, Roy Acuff Theater (later renamed BellSouth Acuff Theater), and the Grand Ole Opry Museum remained in constant use throughout and after demolition of the park. The buildings that once housed the Roy Acuff and Minnie Pearl museums eventually became the administrative offices of WSM radio. The Gaslight Theater became home to Gaylord Opryland's annual ICE! exhibit, and was utilized as a rental facility for television production, banquets, and other events. It was the only building left standing that once occupied the gated theme park.
Though much of the hardware had been removed, the course of the Grizzly River Rampage water ride was visible along the path between Opry Mills and Gaylord Opryland for fourteen years after the ride entertained its final guests. In the fall of 2011, Gaylord Entertainment built a new events center designed mainly to hold the hotel's yearly "ICE!" exhibit nearby, clearing the old Grizzly River Rampage site in the process. By November 2011, all recognizable remnants of the theme park were gone.
In 2004, The Tennessean newspaper published a statement by Gaylord Entertainment claiming that current company executives had found no evidence that previous management ever had a business plan for Opryland, let alone any strategic analysis that led to closing it, and that no compelling reasons had been found for the park's closure. Most of the Opryland-era executives left Gaylord Entertainment early in the decade when it was refocused into a more hospitality-oriented company. In 2012, Gaylord CEO Colin Reed called the closing of Opryland "a bad idea," and said he spent much of his first year at Gaylord fielding complaints about it (he arrived at the company in 2001, more than three years after the park was demolished).[9][10]
On January 19, 2012, Gaylord Entertainment announced plans to open a new theme park in Nashville near Opryland's former location. The plans called for a park that could be used nearly year-round, as a water park in the summer and snow park in the winter. It was planned to be a joint venture with Dolly Parton and Herschend Family Entertainment (owners/operators of Dollywood in Pigeon Forge, Tennessee) and was expected to open in 2014,[11] but Parton and Herschend backed out of the plans a few months later, citing Gaylord's decision to sell the rights to operate its hotel chain to Marriott International as a reason for exiting.[12] As a result of the joint venture's collapse, the project was scrapped.
As the company transitioned into a real estate investment trust in 2012, Gaylord Entertainment was renamed Ryman Hospitality Properties.
2010 Tennessee floods

The Opryland site was flooded in early May 2010, after two days of torrential downpours in the Nashville area caused the Cumberland River to overflow its banks.
The flood itself did not destroy any buildings on Gaylord's property, but every building on site was severely damaged by the floodwater. Buildings that were demolished—rather than repaired—after the flood include the Roy Acuff Theater, Gaslight Theater, the Gaylord University building, the WSM administration buildings (former Minnie Pearl and Roy Acuff museums), and the former Opryland Hospitality Center.
Gaylord Opryland, the Grand Ole Opry House, and the General Jackson were closed for several months and all reopened in late 2010. The Grand Ole Opry Museum has remained closed, though the building underwent remediation following the flood. The fate of its contents is unknown. Opry Mills became entangled in a legal battle over flood insurance payout (which, as of March 2015, is ongoing),[13] stalling its flood repairs for several months, and fully reopened on March 29, 2012.
As of July 2016, the Grand Ole Opry House, Roy Acuff's former home, and the building that once housed the Grand Ole Opry Museum are the only theme park-era structures remaining on the property. The Cumberland Landing building was relocated from the gates of the theme park to the riverbank upon demolition of the park. It was vacated following the flood and remains out of use, but is still standing.
Park Areas
Opryland contained nine themed areas, most of which featured a motif centered on various types of American music.
Opry Plaza
Opry Plaza served as the main entry and exit point for Opryland, and contained the park's three primary gates. The majority of Opry Plaza sat outside the gates, meaning it was accessible to guests with or without park tickets. It had an antebellum-inspired architectural theme, and featured music from Grand Ole Opry members playing on the speakers. Its centerpiece was the Grand Ole Opry House. Opry Plaza housed no thrill attractions, but was home to the park's ticket booths, as well as the Roy Acuff Theatre, Grand Ole Opry Museum, Opryland Hospitality Center, Southern Living Cumberland River Cottage, WSM-FM studio, and the Gaslight Theatre/TNN Studio. Opry Plaza connected to Hill Country, Doo Wah Diddy City, and the parking lot.
During and after the park's demolition, portions of Opry Plaza remained undisturbed and open for business. Today, it continues to serve as the area surrounding the Grand Ole Opry House, though many of its remaining buildings were demolished following the 2010 Tennessee floods.
Hill Country
Hill Country was themed around bluegrass music and was designed to resemble the Appalachia region of the United States. It featured the Martin Guitars Country & Bluegrass Theatre. The main attraction of Hill Country was the Dulcimer Splash log ride (originally named Flume Zoom). The Grinder's Switch Train Station (named for the real-life railroad switch that represented the fictitious hometown of Grand Ole Opry star Minnie Pearl) was also located in this area, providing round-trip service to the El Paso Train Station in American West Area. Hill Country connected to Opry Plaza and New Orleans Area.
New Orleans Area
The New Orleans Area was themed around jazz music. Buildings in the area resembled architecture in the French Quarter area of New Orleans, Louisiana. It contained the New Orleans Bandstand, which featured live jazz shows throughout the day, and often played host to a comedy-music show featuring Opry star Mike Snider. The Screamin' Delta Demon roller coaster was added to the New Orleans Area in 1984, extending the theme to include the Mississippi River Delta. A new park gate was built adjacent to the Demon, but it was not prominently promoted. One of the two Skyride stations was located in New Orleans Area, offering one-way service to Doo Wah Diddy City. New Orleans Area connected to Hill Country, Riverside Area, and the parking lot.
Riverside Area
The Riverside Area had no specific musical or architectural theme, and was named such because it bordered the Cumberland River, although the riverbank was not prominently featured. It was home to the American Music Theater, the gated park's only indoor venue. The American Music Theatre was home to "I Hear America Singing," changing over to "For Me And My Gal" in 1982, then "The Big Broadcast," and "And The Winner Is..."  In later years "For Me And My Gal" was revived in this venue. The Opryland Carousel was located at Riverside, as well as K.C.'s Kids' Club, one of the park's two attractions geared exclusively toward children. Prior to the introduction of the K.C. character, the children's area had been sponsored by General Mills, with the attractions featuring cartoon characters from its various brands of cereals. Riverside Area connected to New Orleans Area and American West Area.
American West Area
The American West Area celebrated the American frontier and featured Western music. In the late 1970s and early 1980s a theatre in the shape of a showboat hosted a live show with music from (or in the styles of) the 1890s – 1900. In 1983 the façade of the theatre was changed and hosted "Sing Tennessee" – a version of the show produced by Opryland for the 1982 World's Fair in Knoxville. By the mid 1980s the theatre was converted again to the Durango Theatre, home to the long-running "Way Out West" musical production. The Tin Lizzie antique car ride was located here until 1994, when it was replaced by The Hangman inverted roller coaster, the last major attraction to be installed at Opryland. The American West Area also housed the El Paso Train Station, which provided round-trip service to Grinder's Switch Train Station in Hill Country. American West Area served as somewhat of a hub for the park, as its central location allowed it to connect to Riverside Area, Lakeside Area, as well as Doo Wah Diddy City near its intersection with Grizzly Country.
Lakeside Area
The Lakeside Area celebrated modern country music, and was home to the Theatre By The Lake, host to the long-running "Country Music USA" musical production. It prominently featured a man-made lake, which originally housed the Raft Ride, until it was replaced by the Old Mill Scream in 1987. The Barnstormer airplane ride sat on the lakeshore. It also served as home to the other of the park's two Kids' Club areas, which in its later years, was centered on Professor U.B. Sharp, a character who taught music to children. The Skycoaster was relocated here from State Fair in 1997, in an effort to increase ridership. Lakeside Area connected to State Fair and American West Area.
State Fair
The State Fair area was added to the park in 1975 (replacing a buffalo exhibit) and themed to resemble the midway at a typical state fair, with its central attraction being the Wabash Cannonball roller coaster. Also located in this area was the park's petting zoo, the Country Bumpkin Bump Cars, the Tennessee Waltz swing ride, and a large stable of carnival-style games. State Fair also contained a picnic pavilion, typically closed to the public, designed to host functions for large groups that were visiting the park. State Fair connected to Lakeside Area and Grizzly Country.
Grizzly Country
Grizzly Country was Opryland's last major expansion project, in 1982. It was constructed primarily to house the Grizzly River Rampage river rafting ride. Chaos, an indoor roller coaster, was installed in Grizzly Country in 1989. For a while in the 1980s, Grizzly Country was home to a Mrs. Winner's Chicken & Biscuits location. Grizzly Country connected to State Fair and Doo Wah Diddy City near its intersection with American West Area, and in the park's final two seasons, had a gate that allowed for pedestrian traffic to-and-from Opryland Hotel.
Doo Wah Diddy City
Doo Wah Diddy City, while an original part of the park, was not given its theme until the late 1970s. Though its name implies doo-wop, this area celebrated pop music and rock and roll, beginning with their origins in the 1950s. It was home to the Little Deuce Coupe teacups-style ride, the Rock 'n Roller Coaster (originally called Timber Topper), and a Skyride station offering one-way service to the New Orleans Area. The section featured a dual-sided theatre called the Jukebox and the Flip Side, which was removed in 1992 to make way for Opryland's new centerpiece, the Chevrolet-Geo Celebrity Theatre. Doo Wah Diddy City connected to Opry Plaza, American West Area, and Grizzly Country.
Major Productions

Notable rides

See also
WSM-AM
Grand Ole Opry
Opryland Hotel
The Nashville Network (TNN)
General Jackson (riverboat)
Nashville, Tennessee
Opry Mills

 – a site devoted to preserving Opryland USA's history
 at the Roller Coaster DataBase


Amino acids are organic compounds containing amine (-NH2) and carboxyl (-COOH) functional groups, along with a side chain (R group) specific to each amino acid.[1][2][3] The key elements of an amino acid are carbon (C), hydrogen (H), oxygen (O), and nitrogen (N), although other elements are found in the side chains of certain amino acids. About 500 naturally occurring amino acids are known (though only 20 appear in the genetic code) and can be classified in many ways.[4] They can be classified according to the core structural functional groups' locations as alpha- (α-), beta- (β-), gamma- (γ-) or delta- (δ-) amino acids; other categories relate to polarity, pH level, and side chain group type (aliphatic, acyclic, aromatic, containing hydroxyl or sulfur, etc.). In the form of proteins, amino acid residues form the second-largest component (water is the largest) of human muscles and other tissues.[5] Beyond their role as residues in proteins, amino acids participate in a number of processes such as neurotransmitter transport and biosynthesis.
In biochemistry, amino acids having both the amine and the carboxylic acid groups attached to the first (alpha-) carbon atom have particular importance. They are known as 2-, alpha-, or α-amino acids (generic formula H2NCHRCOOH in most cases,[6] where R is an organic substituent known as a "side chain");[7] often the term "amino acid" is used to refer specifically to these. They include the 22 proteinogenic ("protein-building") amino acids,[8][9][10] which combine into peptide chains ("polypeptides") to form the building-blocks of a vast array of proteins.[11] These are all L-stereoisomers ("left-handed" isomers), although a few D-amino acids ("right-handed") occur in bacterial envelopes, as a neuromodulator (D-serine), and in some antibiotics.[12]
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 ("non-standard" or "non-canonical") are selenocysteine (present in many prokaryotes as well as most eukaryotes, but not coded directly by DNA), and pyrrolysine (found only in some archea and one bacterium). Pyrrolysine and selenocysteine are encoded via variant codons; for example, selenocysteine is encoded by stop codon and SECIS element.[13][14][15] N-formylmethionine (which is often the initial amino acid of proteins in bacteria, mitochondria, and chloroplasts) is generally considered as a form of methionine rather than as a separate proteinogenic amino acid. Codon–tRNA combinations not found in nature can also be used to "expand" the genetic code and form novel proteins known as alloproteins incorporating non-proteinogenic amino acids.[16][17][18]
Many important proteinogenic and non-proteinogenic amino acids have biological functions. For example, in the human brain, glutamate (standard glutamic acid) and gamma-amino-butyric acid ("GABA", non-standard gamma-amino acid) are, respectively, the main excitatory and inhibitory neurotransmitters.[19] Hydroxyproline, a major component of the connective tissue collagen, is synthesised from proline. Glycine is a biosynthetic precursor to porphyrins used in red blood cells. Carnitine is used in lipid transport.
Nine proteinogenic amino acids are called "essential" for humans because they cannot be produced from other compounds by the human body and so must be taken in as food. Others may be conditionally essential for certain ages or medical conditions. Essential amino acids may also differ between species.[20]
Because of their biological significance, amino acids are important in nutrition and are commonly used in nutritional supplements, fertilizers, feed, and food technology. Industrial uses include the production of drugs, biodegradable plastics, and chiral catalysts.
History
The first few amino acids were discovered in the early 19th century.[21][22] In 1806, French chemists Louis-Nicolas Vauquelin and Pierre Jean Robiquet isolated a compound in asparagus that was subsequently named asparagine, the first amino acid to be discovered.[23][24] Cystine was discovered in 1810,[25] although its monomer, cysteine, remained undiscovered until 1884.[24][26] Glycine and leucine were discovered in 1820.[27] The last of the 20 common amino acids to be discovered was threonine in 1935 by William Cumming Rose, who also determined the essential amino acids and established the minimum daily requirements of all amino acids for optimal growth.[28][29]
The unity of the chemical category was recognized by Wurtz in 1865, but he gave no particular name to it.[30] Usage of the term "amino acid" in the English language is from 1898,[31] while the German term, Aminosäure, was used earlier.[32] Proteins were found to yield amino acids after enzymatic digestion or acid hydrolysis. In 1902, Emil Fischer and Franz Hofmeister independently proposed that proteins are formed from many amino acids, whereby bonds are formed between the amino group of one amino acid with the carboxyl group of another, resulting in a linear structure that Fischer termed "peptide".[33]
General structure

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 carboxyl group (which is therefore numbered 2 in the carbon chain starting from that functional group) is called the α–carbon.  Amino acids containing an amino group bonded directly to the alpha carbon are referred to as alpha amino acids.[34]  These include amino acids such as proline which contain secondary amines, which used to be often referred to as "imino acids".[35][36][37]
Isomerism
The alpha amino acids are the most common form found in nature, but only when occurring in the L-isomer. The alpha carbon is a chiral carbon atom, with the exception of glycine which has two indistinguishable hydrogen atoms on the alpha carbon.[38]  Therefore, all alpha amino acids but glycine can exist in either of two enantiomers, called L or D amino acids, which are mirror images of each other (see also Chirality). While L-amino acids represent all of the amino acids found in proteins during translation in the ribosome, D-amino acids are found in some proteins produced by enzyme posttranslational modifications after translation and translocation to the endoplasmic reticulum, as in exotic sea-dwelling organisms such as cone snails.[39] They are also abundant components of the peptidoglycan cell walls of bacteria,[40] and D-serine may act as a neurotransmitter in the brain.[41] D-amino acids are used in racemic crystallography to create centrosymmetric crystals, which (depending on the protein) may allow for easier and more robust protein structure determination.[42] The L and D convention for amino acid configuration refers not to the optical activity of the amino acid itself but rather to the optical activity of the isomer of glyceraldehyde from which that amino acid can, in theory, be synthesized (D-glyceraldehyde is dextrorotatory; L-glyceraldehyde is levorotatory).
In alternative fashion, the (S) and (R) designators are used to indicate the absolute stereochemistry. Almost all of the amino acids in proteins are (S) at the α carbon, with cysteine being (R) and glycine non-chiral.[43] Cysteine has its side chain in the same geometric position as the other amino acids, but the R/S terminology is reversed because of the higher atomic number of sulfur compared to the carboxyl oxygen gives the side chain a higher priority, whereas the atoms in most other side chains give them lower priority.
Side chains

In amino acids that have a carbon chain attached to the α–carbon (such as lysine, shown to the right) the carbons are labeled in order as α, β, γ, δ, and so on.[44] In some amino acids, the amine group is attached to the β or γ-carbon, and these are therefore referred to as beta or gamma amino acids.
Amino acids are usually classified by the properties of their side chain into four groups. The side chain can make an amino acid a weak acid or a weak base, and a hydrophile if the side chain is polar or a hydrophobe if it is nonpolar.[38] The chemical structures of the 22 standard amino acids, along with their chemical properties, are described more fully in the article on these proteinogenic amino acids.
The phrase "branched-chain amino acids" or BCAA refers to the amino acids having aliphatic side chains that are non-linear; these are leucine, isoleucine, and valine. Proline is the only proteinogenic amino acid whose side-group links to the α-amino group and, thus, is also the only proteinogenic amino acid containing a secondary amine at this position.[38] In chemical terms, proline is, therefore, an imino acid, since it lacks a primary amino group,[45] although it is still classed as an amino acid in the current biochemical nomenclature,[46] and may also be called an "N-alkylated alpha-amino acid".[47]
Zwitterions

The α-carboxylic acid group of amino acids is a weak acid, meaning that it releases a hydron (such as a proton) at moderate pH values.  In other words, carboxylic acid groups (−CO2H) can be deprotonated to become negative carboxylates (−CO2− ).  The negatively charged carboxylate ion predominates at pH values greater than the pKa of the carboxylic acid group (mean for the 20 common amino acids is about 2.2, see the table of amino acid structures above).  In a complementary fashion, the α-amine of amino acids is a weak base, meaning that it accepts a proton at moderate pH values.  In other words, α-amino groups (NH2−) can be protonated to become positive α-ammonium groups (+NH3−).  The positively charged α-ammonium group predominates at pH values less than the pKa of the α-ammonium group (mean for the 20 common α-amino acids is about 9.4).
Because all amino acids contain amine and carboxylic acid functional groups, they share amphiprotic properties.[38]  Below pH 2.2, the predominant form will have a neutral carboxylic acid group and a positive α-ammonium ion (net charge +1), and above pH 9.4, a negative carboxylate and neutral α-amino group (net charge −1).  But at pH between 2.2 and 9.4, an amino acid usually contains both a negative carboxylate and a positive α-ammonium group, as shown in structure (2) on the right, so has net zero charge.  This molecular state is known as a zwitterion, from the German Zwitter meaning "hermaphrodite" or "hybrid".[48]  The fully neutral form (structure (1) on the left) is a very minor species in aqueous solution throughout the pH range (less than 1 part in 107). Amino acids exist as zwitterions also in the solid phase, and crystallize with salt-like properties unlike typical organic acids or amines.
Isoelectric point

The variation in titration curves when the amino acids can be grouped by category. With the exception of tyrosine, using titration to distinguish among hydrophobic amino acids is problematic.
At pH values between the two pKa values, the zwitterion predominates, but coexists in dynamic equilibrium with small amounts of net negative and net positive ions. At the exact midpoint between the two pKa values, the trace amount of net negative and trace of net positive ions exactly balance, so that average net charge of all forms present is zero.[49] This pH is known as the isoelectric point pI, so pI = ½(pKa1 + pKa2). The individual amino acids all have slightly different pKa values, so have different isoelectric points. For amino acids with charged side chains, the pKa of the side chain is involved. Thus for Asp, Glu with negative side chains, pI = ½(pKa1 + pKaR), where pKaR is the side chain pKa. Cysteine also has potentially negative side chain with pKaR = 8.14, so pI should be calculated as for Asp and Glu, even though the side chain is not significantly charged at neutral pH. For His, Lys, and Arg with positive side chains, pI = ½(pKaR + pKa2). Amino acids have zero mobility in electrophoresis at their isoelectric point, although this behaviour is more usually exploited for peptides and proteins than single amino acids. Zwitterions have minimum solubility at their isoelectric point and some amino acids (in particular, with non-polar side chains) can be isolated by precipitation from water by adjusting the pH to the required isoelectric point.
Occurrence and functions in biochemistry

Proteinogenic amino acids

Amino acids are the structural units (monomers) that make up proteins. They join together to form short polymer chains called peptides or longer chains called either polypeptides or proteins. These polymers are linear and unbranched, with each amino acid within the chain attached to two neighboring amino acids. The process of making proteins encoded by DNA/RNA genetic material is called translation and involves the step-by-step addition of amino acids to a growing protein chain by a ribozyme that is called a ribosome.[50] The order in which the amino acids are added is read through the genetic code from an mRNA template, which is an RNA copy of one of the organism's genes.
Twenty-two amino acids are naturally incorporated into polypeptides and are called proteinogenic or natural amino acids.[38] Of these, 20 are encoded by the universal genetic code. The remaining 2, selenocysteine and pyrrolysine, are incorporated into proteins by unique synthetic mechanisms. Selenocysteine is incorporated when the mRNA being translated includes a SECIS element, which causes the UGA codon to encode selenocysteine instead of a stop codon.[51] Pyrrolysine is used by some methanogenic archaea in enzymes that they use to produce methane. It is coded for with the codon UAG, which is normally a stop codon in other organisms.[52] This UAG codon is followed by a PYLIS downstream sequence.[53]
Non-proteinogenic amino acids

Aside from the 22 proteinogenic amino acids, many non-proteinogenic amino acids are known. Those either are not found in proteins (for example carnitine, GABA, levothyroxine) or are not produced directly and in isolation by standard cellular machinery (for example, hydroxyproline and selenomethionine).
Non-proteinogenic amino acids that are found in proteins are formed by post-translational modification, which is modification after translation during protein synthesis. These modifications are often essential for the function or regulation of a protein.  For example, the carboxylation of glutamate allows for better binding of calcium cations,[54] and  collagen contains hydroxyproline, generated by hydroxylation of proline.[55] Another example is the formation of hypusine in the translation initiation factor EIF5A, through modification of a lysine residue.[56] Such modifications can also determine the localization of the protein, e.g., the addition of long hydrophobic groups can cause a protein to bind to a phospholipid membrane.[57]
Some non-proteinogenic amino acids are not found in proteins. Examples include 2-aminoisobutyric acid and the neurotransmitter gamma-aminobutyric acid. Non-proteinogenic amino acids often occur as intermediates in the metabolic pathways for standard amino acids– for example, ornithine and citrulline occur in the urea cycle, part of amino acid catabolism (see below).[58] A rare exception to the dominance of α-amino acids in biology is the β-amino acid beta alanine (3-aminopropanoic acid), which is used in plants and microorganisms in the synthesis of pantothenic acid (vitamin B5), a component of coenzyme A.[59]
D-amino acid natural abundance
D-isomers are uncommon in live organisms. For instance, gramicidin is a polypeptide made up from mixture of D- and L-amino acids.[60] Other compounds containing D-amino acid are tyrocidine and valinomycin. These compounds disrupt bacterial cell walls, particularly in Gram-positive bacteria. Only 837 D-amino acids were found in Swiss-Prot database (187 million amino acids analysed).[61]
Non-standard amino acids
The 20 amino acids that are encoded directly by the codons of the universal genetic code are called standard or canonical amino acids. A modified form of methionine (N-formylmethionine) is often incorporated in place of methionine as the initial amino acid of proteins in bacteria, mitochondria and chloroplasts. Other amino acids are called non-standard or non-canonical. Most of the non-standard amino acids are also non-proteinogenic (i.e. they cannot be incorporated into proteins during translation), but two of them are proteinogenic, as they can be incorporated translationally into proteins by exploiting information not encoded in the universal genetic code.
The two non-standard proteinogenic amino acids are selenocysteine (present in many non-eukaryotes as well as most eukaryotes, but not coded directly by DNA) and pyrrolysine (found only in some archaea and one bacterium). The incorporation of these non-standard amino acids is rare. For example, 25 human proteins include selenocysteine (Sec) in their primary structure,[62] and the structurally characterized enzymes (selenoenzymes) employ Sec as the catalytic moiety in their active sites.[63] Pyrrolysine and selenocysteine are encoded via variant codons. For example, selenocysteine is encoded by stop codon and SECIS element.[13][14][15]
In human nutrition

When taken up into the human body from the diet, the 20 standard amino acids either are used to synthesize proteins and other biomolecules or are oxidized to urea and carbon dioxide as a source of energy.[64] The oxidation pathway starts with the removal of the amino group by a transaminase; the amino group is then fed into the urea cycle. The other product of transamidation is a keto acid that enters the citric acid cycle.[65] Glucogenic amino acids can also be converted into glucose, through gluconeogenesis.[66] Of the 20 standard amino acids, nine (His, Ile, Leu, Lys, Met, Phe, Thr, Trp and Val) are called essential amino acids because the human body cannot synthesize them from other compounds at the level needed for normal growth, so they must be obtained from food.[67][68][69] In addition, cysteine, taurine, tyrosine, and arginine are considered semiessential amino-acids in children (though taurine is not technically an amino acid), because the metabolic pathways that synthesize these amino acids are not fully developed.[70][71] The amounts required also depend on the age and health of the individual, so it is hard to make general statements about the dietary requirement for some amino acids. Dietary exposure to the non-standard amino acid BMAA has been linked to human neurodegenerative diseases, including ALS.[72][73]

Non-protein functions

In humans, non-protein amino acids also have important roles as metabolic intermediates, such as in the biosynthesis of the neurotransmitter gamma-amino-butyric acid (GABA). Many amino acids are used to synthesize other molecules, for example:
Tryptophan is a precursor of the neurotransmitter serotonin.[80]
Tyrosine (and its precursor phenylalanine) are precursors of the catecholamine neurotransmitters dopamine, epinephrine and norepinephrine and various trace amines.
Phenylalanine is a precursor of phenethylamine and tyrosine in humans.  In plants, it is a precursor of various phenylpropanoids, which are important in plant metabolism.
Glycine is a precursor of porphyrins such as heme.[81]
Arginine is a precursor of nitric oxide.[82]
Ornithine and S-adenosylmethionine are precursors of polyamines.[83]
Aspartate, glycine, and glutamine are precursors of nucleotides.[84] However, not all of the functions of other abundant non-standard amino acids are known.
Some non-standard amino acids are used as defenses against herbivores in plants.[85] For example, canavanine is an analogue of arginine that is found in many legumes,[86] and in particularly large amounts in Canavalia gladiata (sword bean).[87] This amino acid protects the plants from predators such as insects and can cause illness in people if some types of legumes are eaten without processing.[88] The non-protein amino acid mimosine is found in other species of legume, in particular Leucaena leucocephala.[89] This compound is an analogue of tyrosine and can poison animals that graze on these plants.
Uses in industry
Amino acids are used for a variety of applications in industry, but their main use is as additives to animal feed. This is necessary, since many of the bulk components of these feeds, such as soybeans, either have low levels or lack some of the essential amino acids: lysine, methionine, threonine, and tryptophan are most important in the production of these feeds.[90] In this industry, amino acids are also used to chelate metal cations in order to improve the absorption of minerals from supplements, which may be required to improve the health or production of these animals.[91]
The food industry is also a major consumer of amino acids, in particular, glutamic acid, which is used as a flavor enhancer,[92] and aspartame (aspartyl-phenylalanine-1-methyl ester) as a low-calorie artificial sweetener.[93] Similar technology to that used for animal nutrition is employed in the human nutrition industry to alleviate symptoms of mineral deficiencies, such as anemia, by improving mineral absorption and reducing negative side effects from inorganic mineral supplementation.[94]
The chelating ability of amino acids has been used in fertilizers for agriculture to facilitate the delivery of minerals to plants in order to correct mineral deficiencies, such as iron chlorosis. These fertilizers are also used to prevent deficiencies from occurring and improving the overall health of the plants.[95] The remaining production of amino acids is used in the synthesis of drugs and cosmetics.[90]
Similarly, some amino acids derivatives are used in pharmaceutical industry. They include 5-HTP (5-hydroxytryptophan) used for experimental treatment of depression,[96] L-DOPA (L-dihydroxyphenylalanine) for Parkinson's treatment,[97] and eflornithine drug that inhibits ornithine decarboxylase and used in the treatment of sleeping sickness.[98]
Expanded genetic code

Since 2001, 40 non-natural amino acids have been added into protein by creating a unique codon (recoding) and a corresponding transfer-RNA:aminoacyl– tRNA-synthetase pair to encode it with diverse physicochemical and biological properties in order to be used as a tool to exploring protein structure and function or to create novel or enhanced proteins.[16][17]
Nullomers

Nullomers are codons that in theory code for an amino acid, however in nature there is a selective bias against using this codon in favor of another, for example bacteria prefer to use CGA instead of AGA to code for arginine.[99] This creates some sequences that do not appear in the genome.  This characteristic can be taken advantage of and used to create new selective cancer-fighting drugs[100] and to prevent cross-contamination of DNA samples from crime-scene investigations.[101]
Chemical building blocks

Amino acids are important as low-cost feedstocks. These compounds are used in chiral pool synthesis as enantiomerically pure building-blocks.[102]
Amino acids have been investigated as precursors chiral catalysts, e.g., for asymmetric hydrogenation reactions, although no commercial applications exist.[103]
Biodegradable plastics

Amino acids are under development as components of a range of biodegradable polymers. These materials have applications as environmentally friendly packaging and in medicine in drug delivery and the construction of prosthetic implants. These polymers include polypeptides, polyamides, polyesters, polysulfides, and polyurethanes with amino acids either forming part of their main chains or bonded as side chains. These modifications alter the physical properties and reactivities of the polymers.[104] An interesting example of such materials is polyaspartate, a water-soluble biodegradable polymer that may have applications in disposable diapers and agriculture.[105] Due to its solubility and ability to chelate metal ions, polyaspartate is also being used as a biodegradeable anti-scaling agent and a corrosion inhibitor.[106][107] In addition, the aromatic amino acid tyrosine is being developed as a possible replacement for toxic phenols such as bisphenol A in the manufacture of polycarbonates.[108]
Reactions
As amino acids have both a primary amine group and a primary carboxyl group, these chemicals can undergo most of the reactions associated with these functional groups. These include nucleophilic addition, amide bond formation, and imine formation for the amine group, and esterification, amide bond formation, and decarboxylation for the carboxylic acid group.[109] The combination of these functional groups allow amino acids to be effective polydentate ligands for metal-amino acid chelates.[110]
The multiple side chains of amino acids can also undergo chemical reactions.[111] The types of these reactions are determined by the groups on these side chains and are, therefore, different between the various types of amino acid.
Chemical synthesis

Several methods exist to synthesize amino acids. One of the oldest methods begins with the bromination at the α-carbon of a carboxylic acid. Nucleophilic substitution with ammonia then converts the alkyl bromide to the amino acid.[112] In alternative fashion, the Strecker amino acid synthesis involves the treatment of an aldehyde with potassium cyanide and ammonia, this produces an α-amino nitrile as an intermediate. Hydrolysis of the nitrile in acid then yields an α-amino acid.[113] Using ammonia or ammonium salts in this reaction gives unsubstituted amino acids, whereas substituting primary and secondary amines will yield substituted amino acids.[114] Likewise, using ketones, instead of aldehydes, gives α,α-disubstituted amino acids.[115] The classical synthesis gives racemic mixtures of α-amino acids as products, but several alternative procedures using asymmetric auxiliaries[116] or asymmetric catalysts[117][118] have been developed.[119]
At the current time, the most-adopted method is an automated synthesis on a solid support (e.g., polystyrene beads), using protecting groups (e.g., Fmoc and t-Boc) and activating groups (e.g., DCC and DIC).
Peptide bond formation

As both the amine and carboxylic acid groups of amino acids can react to form amide bonds, one amino acid molecule can react with another and become joined through an amide linkage. This polymerization of amino acids is what creates proteins. This condensation reaction yields the newly formed peptide bond and a molecule of water. In cells, this reaction does not occur directly; instead, the amino acid is first activated by attachment to a transfer RNA molecule through an ester bond. This aminoacyl-tRNA is produced in an ATP-dependent reaction carried out by an aminoacyl tRNA synthetase.[120] This aminoacyl-tRNA is then a substrate for the ribosome, which catalyzes the attack of the amino group of the elongating protein chain on the ester bond.[121] As a result of this mechanism, all proteins made by ribosomes are synthesized starting at their N-terminus and moving toward their C-terminus.
However, not all peptide bonds are formed in this way. In a few cases, peptides are synthesized by specific enzymes. For example, the tripeptide glutathione is an essential part of the defenses of cells against oxidative stress. This peptide is synthesized in two steps from free amino acids.[122] In the first step, gamma-glutamylcysteine synthetase condenses cysteine and glutamic acid through a peptide bond formed between the side chain carboxyl of the glutamate (the gamma carbon of this side chain) and the amino group of the cysteine. This dipeptide is then condensed with glycine by glutathione synthetase to form glutathione.[123]
In chemistry, peptides are synthesized by a variety of reactions. One of the most-used in solid-phase peptide synthesis uses the aromatic oxime derivatives of amino acids as activated units. These are added in sequence onto the growing peptide chain, which is attached to a solid resin support.[124] The ability to easily synthesize vast numbers of different peptides by varying the types and order of amino acids (using combinatorial chemistry) has made peptide synthesis particularly important in creating libraries of peptides for use in drug discovery through high-throughput screening.[125]
Biosynthesis

In plants, nitrogen is first assimilated into organic compounds in the form of glutamate, formed from alpha-ketoglutarate and ammonia in the mitochondrion. In order to form other amino acids, the plant uses transaminases to move the amino group to another alpha-keto carboxylic acid. For example, aspartate aminotransferase converts glutamate and oxaloacetate to alpha-ketoglutarate and aspartate.[126] Other organisms use transaminases for amino acid synthesis, too.
Nonstandard amino acids are usually formed through modifications to standard amino acids. For example, homocysteine is formed through the transsulfuration pathway or by the demethylation of methionine via the intermediate metabolite S-adenosyl methionine,[127] while hydroxyproline is made by a posttranslational modification of proline.[128]
Microorganisms and plants can synthesize many uncommon amino acids. For example, some microbes make 2-aminoisobutyric acid and lanthionine, which is a sulfide-bridged derivative of alanine. Both of these amino acids are found in peptidic lantibiotics such as alamethicin.[129] However, in plants, 1-aminocyclopropane-1-carboxylic acid is a small disubstituted cyclic amino acid that is a key intermediate in the production of the plant hormone ethylene.[130]
Catabolism

Amino acids must first pass out of organelles and cells into blood circulation via amino acid transporters, since the amine and carboxylic acid groups are typically ionized. Degradation of an amino acid, occurring in the liver and kidneys, often involves deamination by moving its amino group to alpha-ketoglutarate, forming glutamate. This process involves transaminases, often the same as those used in amination during synthesis. In many vertebrates, the amino group is then removed through the urea cycle and is excreted in the form of urea. However, amino acid degradation can produce uric acid or ammonia instead. For example, serine dehydratase converts serine to pyruvate and ammonia.[84] After removal of one or more amino groups, the remainder of the molecule can sometimes be used to synthesize new amino acids, or it can be used for energy by entering glycolysis or the citric acid cycle, as detailed in image at right.
Physicochemical properties of amino acids
The 20 amino acids encoded directly by the genetic code can be divided into several groups based on their properties. Important factors are charge, hydrophilicity or hydrophobicity, size, and functional groups.[38] These properties are important for protein structure and protein–protein interactions. The water-soluble proteins tend to have their hydrophobic residues (Leu, Ile, Val, Phe, and Trp) buried in the middle of the protein, whereas hydrophilic side chains are exposed to the aqueous solvent. (Note that in biochemistry, a residue refers to a specific monomer within the polymeric chain of a polysaccharide, protein or nucleic acid.) The integral membrane proteins tend to have outer rings of exposed hydrophobic amino acids that anchor them into the lipid bilayer. In the case part-way between these two extremes, some peripheral membrane proteins have a patch of hydrophobic amino acids on their surface that locks onto the membrane. In similar fashion, proteins that have to bind to positively charged molecules have surfaces rich with negatively charged amino acids like glutamate and aspartate, while proteins binding to negatively charged molecules have surfaces rich with positively charged chains like lysine and arginine. There are different hydrophobicity scales of amino acid residues.[132]
Some amino acids have special properties such as cysteine, that can form covalent disulfide bonds to other cysteine residues, proline that forms a cycle to the polypeptide backbone, and glycine that is more flexible than other amino acids.
Many proteins undergo a range of posttranslational modifications, when additional chemical groups are attached to the amino acids in proteins. Some modifications can produce hydrophobic lipoproteins,[133] or hydrophilic glycoproteins.[134] These type of modification allow the reversible targeting of a protein to a membrane. For example, the addition and removal of the fatty acid palmitic acid to cysteine residues in some signaling proteins causes the proteins to attach and then detach from cell membranes.[135]
Table of standard amino acid abbreviations and properties

Two additional amino acids are in some species coded for by codons that are usually interpreted as stop codons:

In addition to the specific amino acid codes, placeholders are used in cases where chemical or crystallographic analysis of a peptide or protein cannot conclusively determine the identity of a residue. They are also used to summarise conserved protein sequence motifs. The use of single letters to indicate sets of similar residues is similar to the use of abbreviation codes for degenerate bases.[140][141]

Unk is sometimes used instead of Xaa, but is less standard.
In addition, many non-standard amino acids have a specific code. For example, several peptide drugs, such as Bortezomib and MG132, are artificially synthesized and retain their protecting groups, which have specific codes. Bortezomib is Pyz-Phe-boroLeu, and MG132 is Z-Leu-Leu-Leu-al. To aid in the analysis of protein structure, photo-reactive amino acid analogs are available. These include photoleucine (pLeu) and photomethionine (pMet).[142]
See also

Amino acid dating
Beta-peptide
Degron
Erepsin
Homochirality
Hyperaminoacidemia
Leucines
Miller–Urey experiment
Nucleic acid sequence
Proteinogenic amino acid
Table of codons, 3-nucleotide sequences that encode each amino acid

References and notes

Further reading

 Cite uses deprecated parameter |deadurl= (help)CS1 maint: BOT: original-url status unknown (link)

 Media related to Main Page at Wikimedia Commons


BioWare is a Canadian video game developer based in Edmonton, Alberta. It was founded in May 1995 by newly graduated medical doctors Ray Muzyka and Greg Zeschuk, alongside Trent Oster, Brent Oster, Marcel Zeschuk and Augustine Yip. As of 2007, the company is owned by American publisher Electronic Arts.
BioWare specializes in role-playing video games, and achieved recognition for developing highly praised and successful licensed franchises: Baldur's Gate, Neverwinter Nights, and Star Wars: Knights of the Old Republic. They proceeded to make several other successful games based on original intellectual property: Jade Empire, the Mass Effect series, and the Dragon Age series. In 2011, BioWare launched their first massively multiplayer online role-playing game, Star Wars: The Old Republic.
History
Foundation

BioWare was established on 22 May 1995,[2] by Ray Muzyka and Greg Zeschuk, alongside Trent Oster, his brother Brent, Zeschuk's cousin Marcel, and Augustine Yip.[3] Of the founding team, Muzyka and Greg Zeschuk had recently graduated from medical school at the University of Alberta, and had a background in programming for use in school.[4] Together with Yip, they had created a medical simulation programme.[4] The three also played video games for recreation, eventually deciding to develop their own.[4] Their success in the medical field provided them with the funding they needed to launch a video game company. To make their first game, they pooled their resources, which resulted in capital of $100,000.[4]
1990s: Shattered Steel and Baldur's Gate
Their first game, Shattered Steel, began its life as a proof-of-concept demo, similar to the MechWarrior games. This demo was submitted to ten publishers, seven of whom returned to the company with an offer. A publishing deal for Shattered Steel was eventually signed with Interplay Entertainment. Brent Oster and Trent Oster left BioWare at that time to form Pyrotek Studios, which continued developing Shattered Steel but broke up a year later, with Trent returning to BioWare to finish the game.[5] BioWare's first game was released the following year. Shattered Steel's release was described by IGN as a "modest success" with "decent sales". Two noteworthy points were the deformable terrain (player weapon damage caused craters in the environment) and zone damage (well-placed gunfire could shoot mounted weapons off enemies). A sequel to Shattered Steel was planned for 1998 but never realized.[4]
BioWare's founders and staff were keenly interested in both computerized and pen-and-paper variants of role-playing games. Their next development project, therefore, was determined to be a role-playing game. When Interplay financed "exploratory development", BioWare presented the publishers with a demo called Battleground: Infinity. Interplay suggested that the demonstrated gameplay engine would be well-suited to the Dungeons & Dragons licence which it had acquired from Strategic Simulations. Accordingly, Infinity was reworked in line with the Dungeons & Dragons ruleset.[4]
This resulted in Baldur's Gate, which witnessed a development cycle of three years. During this time, the three doctors continued to practice medicine. However, in the final years of the project, the demands of development prompted Muzyka and Zeschuck to leave medicine and move into full-time development. Augustine Yip decided to continue with his medical practice. Baldur's Gate sold more than two million copies after its release, nearly matching the sales of Diablo. Following the success of Baldur's Gate, the Infinity Engine was used for the games Planescape: Torment and the Icewind Dale series. The success of Baldur's Gate was followed by an expansion pack for the game: Tales of the Sword Coast.[6]
2000s: EA acquisition, Mass Effect and Dragon Age

At this point, BioWare decided to return to the action genre. The company's initial thought was to develop a sequel to Shattered Steel, but eventually a sequel to MDK from Shiny Entertainment was chosen for development.[4] MDK 2 was released on PC, Dreamcast, and eventually PlayStation 2, offering BioWare their first taste of developing games for consoles.[6] MDK 2 drew the same level of praise as its predecessor but, despite the success, BioWare returned to the Baldur's Gate series for their next project.[4]
Baldur's Gate II: Shadows of Amn was released in 2000,[6] two years after the release of Baldur's Gate.[4] Baldur's Gate II sold two million copies, matching the sales of the first game in the series. However, the success of both Baldur's Gate II and MDK 2 was not enough to stabilize Interplay financially, who eventually went bankrupt.[4] Following Interplay's bankruptcy, BioWare began to work with Infogrames, which was later renamed to Atari.[6] Neverwinter Nights was originally to be published by Interplay, but the company lost the licence of the game to Atari and part of their Dungeons & Dragons licence to BioWare. After selling their D&D licence to Atari, BioWare developed Star Wars: Knights of the Old Republic and Jade Empire. It had publishing relationships with Interplay Entertainment, Infogrames and, under its new name Atari, LucasArts, and Microsoft.
The next few years saw a number of changes in BioWare's corporate status. In November 2005, it was announced that BioWare and Pandemic Studios (itself founded by former Activision employees) would be joining forces, with private equity fund Elevation Partners investing in the partnership. On 11 October 2007, however, it was announced that this new partnership (organized as VG Holding Corp) had been bought by Electronic Arts.[7] BioWare therefore became a unit of EA, but retained its own branding.
In 2007, BioWare released the science fiction role-playing game Mass Effect. The following year, BioWare released Sonic Chronicles: The Dark Brotherhood on the Nintendo DS, its first title for a handheld game console. Later, EA announced that BioWare would be merged with Mythic Entertainment, another division of EA, so that they could have all of their role-playing game development in one business unit.
The growth of the MMORPG group as part of Electronic Arts in 2008 has resulted in three additional studios being added to the BioWare group outside BioWare's original home base in Edmonton. The first, located in Austin, Texas, and headed by industry veterans Gordon Walton and Richard Vogel, was created to work on the Star Wars: The Old Republic MMORPG project. Both the studio and the project were announced on 13 March 2006. On 2 March 2009, BioWare announced it had opened a new studio in Montreal, Quebec, to assist with existing projects as necessary.[8] In 2009 Mythic Entertainment, based in Fairfax, Virginia, became part of the RPG/MMO Group, later being renamed BioWare Mythic in early 2010.
On 24 June 2009, Electronic Arts announced a restructuring of their role-playing and massively multiplayer online games development into a new group that included both Mythic Entertainment and BioWare. Ray Muzyka, co-founder and general manager of BioWare, was appointed the Group general manager of this newly formed "BioWare Group". BioWare's other co-founder, Greg Zeschuk, became the Group Creative Officer for the new MMORPG studio group. Rob Denton stepped up as general manager of Mythic, reporting to Muzyka, and later became the Group Operations Officer of the new group. BioWare's studios remained unchanged and continued to report to Muzyka.[9] Near the end of 2009, BioWare released the acclaimed fantasy role-playing game Dragon Age: Origins.
2010s: Muzyka and Zeschuk's departure, Mass Effect on hiatus, Anthem
In January 2010, BioWare released the sequel to Mass Effect, Mass Effect 2, which would go on to receive critical acclaim and more than 60 awards. The company announced that it would be opening up a new customer service office in Galway, Ireland, in 2011.[10] BioWare completed three major games between 2011 and 2012. The massively multiplayer online role-playing game (MMORPG) Star Wars: The Old Republic is based on BioWare's previous contribution to the Star Wars franchise,[11] and was announced on 21 October 2008, although BioWare had first mentioned an unspecified new collaboration with LucasArts in October the previous year.[12] The other games were Dragon Age II, the sequel to Dragon Age: Origins, and Mass Effect 3.[13][14][15]
Following the release of Mass Effect 3 in March 2012, numerous players complained about its endings failing to fulfill the developer's earlier promises regarding the conclusion of the trilogy. In response to these criticisms, BioWare announced on 5 April that they would reschedule their post-release content production and release an "Extended Cut" DLC that would expand the original endings and address the most common points of critique.[16] The Extended Cut was released as a free download on 26 June 2012.[17] In the aftermath of the controversy, Forbes contributor Erik Kain wrote that it "may end up being a healthy one for the industry, opening a new chapter in gamer/developer/publisher relations", calling BioWare and EA's decision to act on the fans' complaints a "remarkable" choice that made gamers realize "that they are entitled, and that it isn't a bad thing, to quality games".[18]
On 18 September 2012, the next day after the official announcement of the third Dragon Age title,[19] both Ray Muzyka and Greg Zeschuk, two of the remaining co-founders of BioWare, simultaneously announced they would be retiring from the gaming industry.[20][21] After almost a year without a formal head, EA appointed Matthew Bromberg the group general manager of the BioWare label on 9 September 2013. Former CEO and president of Major League Gaming, Bromberg worked as the general manager of BioWare Austin since 2012; after his promotion, Jeff Hickman took over as the general manager in Austin. Aaryn Flynn remains in charge of BioWare Canada (Edmonton and Montreal) and Jon Van Caneghem, the head of Victory Games and Waystone Studio (also parts of the BioWare label).[22]
After acquiring and dismantling LucasArts, The Walt Disney Company announced in May 2013 that Electronic Arts will produce future Star Wars games, "in addition to the BioWare team, which is already developing for the Star Wars franchise."[23] In November 2013, teaser images from the next instalment of the Mass Effect series have been released.[24] At E3 2014, BioWare Edmonton announced working on a new (unnamed) original intellectual property in addition to continuing their established series.[25] Another new IP, titled Shadow Realms is an episodic 4 vs. 1 story-driven online action role-playing game, and was announced on Gamescom 2014.[26] On 9 February 2015, Bioware Austin announced that development on Shadow Realms would not continue.[27][28]
Casey Hudson, the creator of the Mass Effect series, left BioWare in May 2014, while Drew Karpyshyn, writer of Star Wars: Knights of the Old Republic, returned in 2015,[29] Dragon Age's writer David Gaider left BioWare in January 2016.[30] Chris Wynn and Chris Schlerf, both of whom had an important role in the development of Mass Effect: Andromeda, left in December 2015 and February 2016 respectively.[31] Alexis Kennedy, co-founder of Failbetter Games and the creative director of Dragon Age: The Last Court, joined BioWare as its "first ever guest writer" in September 2016.[32]
On 13 September 2016, EA announced the formation of EA Worldwide Studios, which would consist of the BioWare Studios, EA Mobile, and Maxis, and led by the DICE co-founder Patrick Soderlund. At the same time, Samantha Ryan, head of EA Mobile and Maxis, was appointed the new head of the BioWare Studios (Aaryn Flynn remained in charge of BioWare Canada).[33] Released in March 2017, Andromeda was at the center of controversy of equal proportions, if not higher than that around the third chapter; starting with heavy criticisms that were addressed before the video game was released[34] to the lukewarm response received by the specialized press and the fandom[35] with sales lower than the previous Mass Effect chapters.[36] Given the circumstances Electronic Arts has reportedly frozen the entire Mass Effect series, downgrading the BioWare Montréal branch from a leading development team to a support team,[37] and later merging it into EA Motive altogether.[38]
During EA's EA Play pre-E3 press conference on 10 June 2017, BioWare revealed Anthem, a new action role-playing game,[39] with BioWare's story writer, Drew Karpyshyn, who previously worked on Mass Effect and Mass Effect 2, contributing to the new game.[40] In July 2017, Aaryn Flynn, General Manager of BioWare, announced that he would depart from the company. Casey Hudson, who left the company in 2014, returned to BioWare as its new General Manager.[41] Lead story developer for Jade Empire and Dragon Age creative director Mike Laidlaw announced his departure from BioWare in October 2017 after 14 years with the company.[42] James Ohlen, the lead designer of the Baldur's Gate series, Neverwinter Nights, Knights of the Old Republic, Jade Empire, and Dragon Age: Origins, as well as the game director of The Old Republic MMO, left the studio after 22 years in July 2018.[43]
Technology
Between 1998 and 2011, BioWare developed a number of in-house video game engines to serve as technical basis for their games. Some of these engines were then licensed to other companies to develop their own games. Others came with modding toolkits, allowing the fan community to implement original adventures using the technology of BioWare's games. BioWare created the Infinity Engine to use it as a core component for development of 2D role-playing video games based on Dungeons & Dragons, the Baldur's Gate series (1998–2001). The engine was also used by Black Isle Studios to create the critically acclaimed Planescape: Torment (1999) and the Icewind Dale series (2000–2002).
The Aurora Engine was the successor to the Infinity Engine, featuring full 3D environments, real-time lighting and shadows, and surround sound.[44] BioWare used the Aurora Engine to produce their 2002 Neverwinter Nights, as well as two expansion packs. The game included the so-called "Aurora toolset", a collection of tools allowing users to create their own digital adventure modules to be played either in single-player or in online multiplayer. The toolset enjoyed great popularity among the modding community, with over a thousand fan-made modules produced in it within half a year after the release.[45] Obsidian Entertainment (successor to Black Isle Studios) used an updated version of BioWare's Aurora, titled "Electron Engine", to produce Neverwinter Nights 2 (2006) and its three expansion packs (2007–2009). Like the original, the Electron toolset was released with the game.[46] The Polish studio CD Projekt Red used the Aurora Engine to develop The Witcher, the 2007 video game adaptation of the Polish fantasy novel series, although the rendering module was rewritten from scratch.
BioWare used an updated version of the Aurora, titled the Odyssey Engine, to produce Star Wars: Knights of the Old Republic in 2003 and their first original intellectual property role-playing game Jade Empire in 2005. The Odyssey Engine was the first BioWare engine to allow developing for video game consoles, with both Knights of the Old Republic and Jade Empire originally released for the Xbox before being ported to the PC platform. Obsidian Entertainment used the Odyssey Engine to develop Star Wars Knights of the Old Republic II: The Sith Lords (2004), a sequel to the original Knights of the Old Republic. BioWare maintained limited oversight on Obsidian's development of The Sith Lords, as well as Neverwinter Nights 2.[47]
The Eclipse Engine, also known as the Lycium Engine, succeeded the Odyssey Engine and, among other things, supported PhysX hardware acceleration.[48] It was used to produce Dragon Age: Origins (2009) and its expansion pack (2010). Like Neverwinter Nights, Origins was released with a toolset to allow the players to run their own adventure modules on the Eclipse Engine.[49] An upgraded version of the Eclipse Engine, internally known as the Lycium Engine, was used to produce Dragon Age 2 (2011).[50]
In 2013, EA confirmed that all future games developed by BioWare will be made on EA DICE's Frostbite 3 engine. Both Dragon Age: Inquisition and Mass Effect Andromeda were announced to be based on the Frostbite 3 engine,[51] as part of the general move towards a unified technology foundation across all of Electronic Arts' development studios.[52]
Subsidiaries
Current
BioWare Austin in Austin, Texas; formed in March 2006 specifically to develop Star Wars: The Old Republic (with assistance from BioWare Edmonton), BioWare Austin later began working on a new IP called Shadow Realms,[53] but production was shelved in February 2015 in order to focus on the continuing production of Dragon Age: Inquisition and The Old Republic.[54]
Former
BioWare Montreal in Montreal, Quebec; formed in March 2009 to assist the Edmonton studio where necessary.[8] Led the development of DLC for the Mass Effect series as well as Mass Effect: Andromeda.[24] BioWare Montreal was merged with EA's Motive Studios in August 2017.[55]
BioWare San Francisco in San Francisco, California; founded as EA2D and developed Mirror's Edge 2D and Dragon Age: Legends, became part of BioWare, but was closed in February 2013.[56][57][58]
BioWare Mythic in Fairfax, Virginia; formerly known as Mythic Entertainment, until June 2009, re-renamed to Mythic Entertainment in November 2012 and closed completely in 2014.[59][60]
Victory Games; founded in February 2011 as BioWare Victory to develop the 2013 Command & Conquer,[61] it had since dropped the BioWare label in November 2012[60] but remained part of the BioWare group.[22] The studio dissolved in October 2013.[62]
Waystone Games; the developer of Dawngate, which was cancelled in November 2014.[63]
BioWare Sacramento in Sacramento, California; founded as KlickNation 2008, acquired and renamed BioWare Sacramento in 2011, and renamed EA Capital Games in 2014.[64]
Games developed

Awards and recognition
The full list of awards can be found on their web site.[65]
Spike TV's 2010 Video Game Awards: Studio of the Year (2010)
Hall of Fame induction (2010)[66]
In addition to numerous game awards, in October 2008, the company was named one of Alberta's Top Employers by Mediacorp Canada Inc., which was announced by the Calgary Herald[67] and the Edmonton Journal.[68][69]
BioWare's co-founders Ray Muzyka and Greg Zeschuk were named as members of the Order of Canada in December 2018 "for [their] revolutionary contributions to the video game industry as a developer and co-founder of an internationally renowned studio."[70]

No URL found. Please specify a URL here or add one to Wikidata.


Petals are modified leaves that surround the reproductive parts of flowers. They are often brightly colored or unusually shaped to attract pollinators. Together, all of the petals of a flower are called a corolla. Petals are usually accompanied by another set of special leaves called sepals, that collectively form the calyx and lie just beneath the corolla. The calyx and the corolla together make up the perianth. When the petals and sepals of a flower are difficult to distinguish, they are collectively called tepals. Examples of plants in which the term tepal is appropriate include genera such as Aloe and Tulipa. Conversely, genera such as Rosa and Phaseolus have well-distinguished sepals and petals. When the undifferentiated tepals resemble petals, they are referred to as "petaloid", as in petaloid monocots, orders of monocots with brightly coloured tepals. Since they include Liliales, an alternative name is lilioid monocots.
Although petals are usually the most conspicuous parts of animal-pollinated flowers, wind-pollinated species, such as the grasses, either have very small petals or lack them entirely.

Corolla

The role of the corolla in plant evolution has been studied extensively since Charles Darwin postulated a theory of the origin of elongated corollae and corolla tubes.[1]
A corolla of separate tepals is apopetalous. If the petals are free from one another in the corolla, the plant is polypetalous or choripetalous; while if the petals are at least partially fused together, it is gamopetalous or sympetalous. In the case of fused tepals, the term is syntepalous. The corolla in some plants forms a tube.
Variations

Petals can differ dramatically in different species.  The number of petals in a flower may hold clues to a plant's classification.  For example, flowers on eudicots (the largest group of dicots) most frequently have four or five petals while flowers on monocots have three or six petals, although there are many exceptions to this rule.[2]
The petal whorl or corolla may be either radially or bilaterally symmetrical (see Symmetry in biology and Floral symmetry).  If all of the petals are essentially identical in size and shape, the flower is said to be regular[3] or actinomorphic (meaning "ray-formed"). Many flowers are symmetrical in only one plane (i.e., symmetry is bilateral) and are termed irregular or zygomorphic (meaning "yoke-" or "pair-formed"). In irregular flowers, other floral parts may be modified from the regular form, but the petals show the greatest deviation from radial symmetry. Examples of zygomorphic flowers may be seen in orchids and members of the pea family.
In many plants of the aster family such as the sunflower, Helianthus annuus, the circumference of the flower head is composed of ray florets.  Each ray floret is anatomically an individual flower with a single large petal.  Florets in the centre of the disc typically have no or very reduced petals. In some plants such as Narcissus the lower part of the petals or tepals are fused to form a floral cup (hypanthium) above the ovary, and from which the petals proper extend.[4][5][6]
Petal often consists of two parts: the upper, broad part, similar to leaf blade, also called the blade and the lower part, narrow, similar to leaf petiole, called the claw,[3] separated from each other at the limb. Claws are developed in petals of some flowers of the family Brassicaceae, such as Erysimum cheiri.
The inception and further development of petals shows a great variety of patterns.[7] Petals of different species of plants vary greatly in colour or colour pattern, both in visible light and in ultraviolet. Such patterns often function as guides to pollinators, and are variously known as nectar guides, pollen guides, and floral guides.
Genetics
The genetics behind the formation of petals, in accordance with the ABC model of flower development, are that sepals, petals, stamens, and carpels are modified versions of each other.  It appears that the mechanisms to form petals evolved very few times (perhaps only once), rather than evolving repeatedly from stamens.[8]
Significance of pollination
Pollination is an important step in the sexual reproduction of higher plants.  Pollen is produced by the male flower or by the male organs of hermaphroditic flowers.
Pollen does not move on its own and thus requires wind or animal pollinators to disperse the pollen to the stigma (botany) of the same or nearby flowers. However, pollinators are rather selective in determining the flowers they choose to pollinate. This develops competition between flowers and as a result flowers must provide incentives to appeal to pollinators (unless the flower self-pollinates or is involved in wind pollination). Petals play a major role in competing to attract pollinators. Henceforth pollination dispersal could occur and the survival of many species of flowers could prolong.
Functions and purposes
Petals have various functions and purposes depending on the type of plant. In general, petals operate to protect some parts of the flower and attract/repel specific pollinators.
Function
This is where the positioning of the flower petals are located on the flower is the corolla e.g. the buttercup having shiny yellow flower petals which contain guidelines amongst the petals in aiding the pollinator towards the nectar. Pollinators have the ability to determine specific flowers they wish to pollinate.[9] Using incentives flowers draw pollinators and set up a mutual relation between each other in which case the pollinators will remember to always guard and pollinate these flowers (unless incentives are not consistently met and competition prevails).[10]
Scent
The petals could produce different scents to allure desirable pollinators[11] or repel undesirable pollinators.[12] Some flowers will also mimic the scents produced by materials such as decaying meat, to attract pollinators to them.[13]
Colour
Various colour traits are used by different petals that could attract pollinators that have poor smelling abilities, or that only come out at certain parts of the day. Some flowers are able to change the colour of their petals as a signal to mutual pollinators to approach or keep away.[14]
Shape and size
Furthermore, the shape and size of the flower/petals is important in selecting the type of pollinators they need. For example, large petals and flowers will attract pollinators at a large distance or that are large themselves.[14]
Collectively the scent, colour and shape of petals all play a role in attracting/repelling specific pollinators and providing suitable conditions for pollinating. Some pollinators include insects, birds, bats and the wind.[14]
In some petals, a distinction can be made between a lower narrowed, stalk-like basal part referred to as the claw, and a wider distal part referred to as the blade (or limb). Often the claw and blade are at an angle with one another.
Types of pollination
Wind pollination

Wind-pollinated flowers often have small, dull petals and produce little or no scent. Some of these flowers will often have no petals at all. Flowers that depend on wind pollination will produce large amounts of pollen because most of the pollen scattered by the wind tends to not reach other flowers.[15]
Attracting insects
Flowers have various regulatory mechanisms in order to attract insects. One such helpful mechanism is the use of colour guiding marks. Insects such as the bee or butterfly can see the ultraviolet marks which are contained on these flowers, acting as an attractive mechanism which is not visible towards the human eye. Many flowers contain a variety of shapes acting to aid with the landing of the visiting insect and also influence the insect to brush against anthers and stigmas (parts of the flower). One such example of a flower is the pohutukawa (Metrosideros excelsa) which acts to regulate colour within a different way. The pohutukawa contains small petals also having bright large red clusters of stamens.[14]
Another attractive mechanism for flowers is the use of scent which is highly attractive towards humans such as the rose, but some are very fragrant within attracting flies as they have a smell of rotting meat. Dark is another factor in which flowers have grown to adapt these conditions so colour lacks vision at night therefore scent is the solution for flowers which are pollinated by night flying insects such as the moth.[14]
Attracting birds
Flowers are also pollinated by birds and must be large and colorful to be visible against natural scenery. Such bird–pollinated native plants include: Kōwhai (Sophora species), flax (Phormium tenax, harakeke) and kākā beak (Clianthus puniceus, kōwhai ngutu-kākā). Flowers adapt the mechanism on their petals to change colour in acting as a communicative mechanism for the bird to visit. An example is the tree fuchsia (Fuchsia excorticata, kōtukutuku) which are green when needing to be pollinated and turn red for the birds to stop coming and pollinating the flower.[14]
Bat-pollinated flowers
Flowers can be pollinated by short tailed bats. An example of this is the dactylanthus (Dactylanthus taylorii). This plant has its home under the ground acting the role of a parasite on the roots of forest trees. The dactylanthus has only its flowers pointing to the surface and the flowers lack colour but have the advantage of containing lots of nectar and a very strong scent. These act as a very useful mechanism in attracting the bat.[16]

Bibliography