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16.4: Oorsig - Biologie

16.4: Oorsig - Biologie



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Amptelike kursusbeskrywing:Hierdie kursus is ontwerp om die biologiese verouderingsproses te ondersoek as deel van die normale ontwikkelingsvolgorde en die proses van verandering van bevrugting tot die dood. Hierdie verouderingsproses word beskou as die ontwikkelingskontinuum wat by alle mense voorkom. Tipiese biologiese verouderingsveranderinge in alle liggaamstelsels, sowel as sommige siekteprosesse, sal bespreek word.
Krediete: 3
Kursusvoorvereistes: Geen

Hierdie kursus is volledig aanlyn. Elke geskeduleerde module kan lesings, bespreking, vasvrae en skriftelike opdragte insluit.

Module 1: Inleiding tot die mens weer, teorieë oor veroudering en sellulêre veroudering
Module 2: Die integumentêre sisteem, skeletstelsel en spierstelsel
Module 3: Die senuweestelsel en spesiale sintuie
Module 4: Die sirkulasie-, immuun- en respiratoriese stelsel
Module 5: Die spysverteringstelsel en urienstelsel
Module 6: Die voortplantings- en endokriene stelsel
Module 7: Kwartaalnavorsingsprojek


16.4: Oorsig - Biologie

Prokariotes toon veel meer voedingsdiversiteit as eukayote.

Twee bronne van energie word gebruik: Foto's vang energie van die sonlig op en Chemotrofe wat energie wat in chemikalieë gestoor word, benut.

Twee bronne van koolstof word deur prokariote gebruik:
Outotrofe verkry koolstofatome uit koolstofdioksied.
Heterotrofe verkry hul koolstofatome uit die organiese verbindings wat in ander organismes voorkom.

Die terme wat beskryf hoe prokariote energie en koolstof verkry, word gekombineer om hul maniere van voeding te beskryf:
-Foto -outotrofe verkry energie uit sonlig en gebruik koolstofdioksied vir koolstof.
-Fotoheterotrofe verkry energie uit sonlig, maar kry hul koolstofatome uit organiese molekules.
-Chemo-outotrofe oes energie uit anorganiese chemikalieë en gebruik koolstofdioksied vir koolstof.
-Chemoheterotrofe verkry energie en koolstof uit organiese molekules.

'n Vinnige en eenvoudige aansig van bogenoemde inligting kan hieronder in pers gesien word.

Fotooutotroof
Energiebron: Sonlig
Koolstofbron: CO2

Chemo-outotroof
Energiebron: Anorganiese materiale
Koolstofbron: CO2

Fotoheterotroof
Energiebron: Sonlig
Koolstofbron: Organiese verbindings

Chemoheterotrop
Energiebron: Organiese verbindings
Koolstofbron: Organiese verbindings


16.4: Oorsig - Biologie

Pantry krammetjies van die genetiese ruil ontmoet - Mei, 2021
Vir baie mense voel geneties gemanipuleerde kos onnatuurlik en afstotend: Visgene in aarbeie? Nee dankie. Teenstanders noem hulle dikwels "Frankenfoods", wat daarop dui dat slegs 'n mal wetenskaplike gene van verskillende spesies op hierdie manier kan kombineer. Maar in die afgelope dekades het bioloë gevind dat die natuur self dikwels vinnig en los speel met DNA. Nou toon nuwe navorsing hoe belangrik hierdie genetiese ruil tussen spesies in grasse was, 'n groep wat voedsel soos rys, mielies, koring en suikerriet insluit.

'n Pleistoseen-legkaart: Uitsterwing in Suid-Amerika
In hierdie strokiesprent volg u die ondersoek van wetenskaplikes Maria en Miguel terwyl hulle 'n paleontologiese raaisel oplos. Sowat 11 000 jaar gelede het meer as 80% van die groot dierespesies in Suid-Amerika uitgesterf. Waarom het dit gebeur? Maria en Miguel bestudeer 'n gebied in Chili met die naam Ultima Esperanza. Hulle ontdek baie verskillende bewyse wat dui op 'n opwarmende klimaat en die koms van mense as die belangrikste oorsake van die uitwissing.


Inhoud

In Mei 1998 het Volkswagen AG die regte verkry om die Bugatti-logo en die handelsnaam Bugatti Automobiles S.A.S. Om die EB 110 -model wat onder die vorige eienaarskap vervaardig is, op te volg, het die motorvervaardiger vinnig 'n reeks konsepmotors vrygestel waarvan die tegnologiese vooruitgang sou eindig in die vorm van die Veyron 16.4.

Tussen Oktober 1998 en September 1999 het Bugatti 'n reeks Giugiaro-ontwerpte konsepvoertuie bekendgestel, elk met permanente vierwielaandrywing en aangedryf deur die Volkswagen-ontwerpte W18-enjin. Die eerste motor, die EB 118, was 'n 2-deur luukse koepee wat by die 1998 Parys Motorskou aangebied is. Die volgende motor, die EB218, was 'n vierdeur-sedan wat op die motorskou in Genève in 1999 aangebied is. Die derde en laaste motor, die 18/3 Chiron, was 'n middelenjin sportmotor wat by die 1999 Internasionale Motorskou in Frankfurt aangebied is. [18]

In Oktober 1999 onthul Bugatti 'n vierde konsepmotor op die motorskou in Tokio. Die EB 18/4 Veyron was 'n mid-enjinsportmotor wat intern onder leiding van Hartmut Warkuß ontwerp is. [19] In 2000 is 'n aangepaste weergawe, die EB 16/4 Veyron, op motorskoue in Detroit, Genève en Parys vertoon. In plaas van die drie-bank W18-enjin van die vier vorige konsepmotors, bevat die EB 16/4 die vier-bank W16-enjinargitektuur wat in elke produksievoorbeeld van die Veyron geïnstalleer is. [20]

Die besluit om die motor te begin, is in 2001 deur die Volkswagen -groep geneem. Die eerste padwaardige prototipe is in Augustus 2003 voltooi. Dit is identies aan die latere reeks, behalwe enkele besonderhede. By die oorgang van ontwikkeling na reeksproduksie moes aansienlike tegniese probleme aangepak word, wat die produksie herhaaldelik tot September 2005 moes vertraag. [21]

Die Veyron EB 16.4 is vernoem ter ere van Pierre Veyron, 'n Bugatti-ontwikkelingsingenieur, toetsbestuurder en maatskappy-renjaer wat saam met die navigator Jean-Pierre Wimille die 1939 24 Hours of Le Mans gewen het terwyl hy 'n Bugatti bestuur het. [22] Die "EB" verwys na die stigter van Bugatti Ettore Bugatti en die "16.4" verwys na die enjin se 16 silinders en vier-turbo-aanjaers. [23]

Bugatti Veyron (2005–2011) Redigeer

Spesifikasies en prestasie Redigeer

Die Veyron beskik oor 'n 8.0-liter, W16-silinder-enjin met vier turbo-motors, gelykstaande aan twee smalhoekige V8-enjins wat aan mekaar vasgebout is. Elke silinder het vier kleppe vir 'n totaal van 64, maar die konfigurasie van elke bank laat twee oorhoofse nokke toe om twee banke silinders te dryf, sodat slegs vier nokasse nodig is. Die enjin word gevoed deur vier turbo -aanjaers en verplaas 7,993 cc (487,8 cu in), met 'n vierkantige 86 x 86 mm (3,39 x 3,39 in) gat en slag.

Die ratkas is 'n dubbelkoppelaar, outomatiese ratkas met sewe ratte, met sewe ratverhoudings, met magnesiumspane agter die stuurwiel en 'n skuif tyd van minder as 150 millisekondes, gebou deur Ricardo van Engeland eerder as Borg-Warner, wat ontwerp het die sesgang -DSG wat in die hoofstroommark van die Volkswagen -groep gebruik word. Die Veyron kan in semi-outomatiese of ten volle outomatiese modus bestuur word. 'n Vervangende transmissie vir die Veyron kos net meer as VS$120 000. [24] Dit het ook 'n permanente vierwielaandrywing met behulp van die Haldex Traction-stelsel. Dit gebruik spesiale Michelin PAX run-flat-bande, wat spesifiek ontwerp is om die Veyron se topspoed te akkommodeer, en kos VS$25 000 per stel. [24] Die bande kan slegs in Frankryk op die wiele gemonteer word, 'n diens wat $ 70,000 kos. [24] Kerb gewig is 1,888 kg (4,162 lb). [25] Dit gee die motor 'n krag-tot-gewig-verhouding, volgens Volkswagen Group se syfers, van 530 pk (390 kW 523 pk) per ton. Die motor se asafstand is 2 710 mm (106,7 duim). Algehele lengte is 4 462 mm (175,7 duim) wat 1 752,6 mm (69,0 duim) oorhang gee. Die breedte is 1 998 mm (78,7 duim) en hoogte 1 204 mm (47,4 duim). Die Bugatti Veyron het 'n totaal van tien verkoelers: [26]

  • 3 hitteruilers vir die lug-tot-vloeistof tussenverkoelers.
  • 3 motor radiator.
  • 1 vir die lugversorgingstelsel.
  • 1 transmissie -olie verkoeler.
  • 1 differensiaal olie verkoeler.
  • 1 motorolie verkoeler

Dit het 'n sleepkoëffisiënt van Cd= 0,41 (normale toestand) en Cd= 0,36 (na verlaging op die grond), [27] en 'n frontarea van 2,07 m 2 (22,3 vierkante voet). [28] Dit gee dit 'n sleeparea, die produk van sleepkoëffisiënt en frontale oppervlakte, van CdA = 0,74 m 2 (8,0 vierkante voet).

Motorvermoe -uitset Redigeer

Volgens Volkswagen Group en gesertifiseer deur TÜV Süddeutschland, het die W16 -enjin wat deur die Veyron gebruik word, 'n dryfkrag van 736 kW (987 pk 1 001 PS) en lewer 1.250 N⋅m (922 lbf⋅ft) wringkrag. [4] [29] [30]

Topspoed wysig

Duitse inspeksiebeamptes het 'n gemiddelde topsnelheid van die oorspronklike weergawe op 408,47 km/h (253,81 mph) [11] tydens toetssessies op die Volkswagen Group se private Ehra-Lessien-toetsbaan op 19 April 2005 aangeteken.

Hierdie topsnelheid het James May amper geëwenaar Hoogste rat in November 2006, by die Ehra-Lessien-toetsbaan, teen 407,5 km/h (253,2 mph). [11] May het opgemerk dat die enjin by topsnelheid 45 000 L (9 900 imp gal) lug per minuut verbruik (soveel as wat 'n mens in vier dae asemhaal). Terug in die Hoogste rat ateljee, mede-aanbieder Jeremy Clarkson het opgemerk dat die meeste sportmotors voel asof hulle uitmekaar skud teen hul topspoed, en het May gevra of dit die geval is met die Veyron teen 407 km/h (253 mph). May het geantwoord dat die Veyron baie beheer is en net effens gewankel het toe die lugrem ontplooi het. [31]

Die motor se normale topsnelheid is 343 km/h (213 mph). As die motor 220 km/h (137 mph) bereik, laat die motor hidrolies sak totdat dit 'n grondvryhoogte van ongeveer 9 cm (3,5 duim) het. Terselfdertyd ontplooi die vleuel en die spoiler. In hierdie hanteringsmodus, verskaf die vlerk 3 425 newton (770 lbf) se afwaartse krag, wat die motor teen die pad hou. [26]

Topspoedmodus moet ingegee word terwyl die voertuig rus. Sy bestuurder moet 'n spesiale topspoedsleutel links van hul sitplek omskakel, wat 'n kontrolelys aktiveer om vas te stel of die motor en sy bestuurder gereed is om te probeer om 407 km/h (253 mph) te bereik. As dit so is, trek die agterspoiler terug, die voorste lugverspreiders sluit en normale grondvryhoogte van 12,5 cm (4,9 in) daal tot 6,5 cm (2,6 in).

Rem wysig

Die remme van die Veyron maak gebruik van kruisgeboorde, radiaal geventileerde koolstofveselversterkte silikonkarbied (C/SiC) saamgestelde skywe, vervaardig deur SGL Carbon, wat minder remverf het en minder weeg as standaard gietysterskywe. [32] Die liggewig monoblok remklauwers van aluminium word vervaardig deur AP Racing, die voorkant het agt [26] titanium suiers en die agterste calipers het ses suiers. Bugatti beweer die maksimum vertraging van 1,3 g op padbande. As 'n bykomende veiligheidsfunksie, is daar ook 'n sluitweerremstelsel (ABS) op die handrem geïnstalleer, in geval van remstorting.

Prototipes is herhaaldelik 1.0 g rem van 312 km/h (194 mph) tot 80 km/h (50 mph) sonder vervaag. Met die motor se versnelling van 80 km/h (50 mph) tot 312 km/h (194 mph) kan die toets elke 22 sekondes uitgevoer word. By snelhede van meer as 200 km/h (124 mph) tree die agterste vleuel ook op as 'n lugrem, wat in 'n hoek van 55 ° in 0,4 sekondes breek sodra remme aangeskakel word, wat 'n ekstra vertraging van 0,68 g (6,66 m/s 2) bied ( gelykstaande aan die stopkrag van 'n gewone luikrug). [26] Bugatti beweer dat die Veyron in minder as 10 sekondes van 400 km/h (249 mph) tot stilstand sal rem, alhoewel die afstand in hierdie tyd 'n halwe kilometer (derde van myl) sal wees. [26]

Spesiale uitgawes Edit

Naam Prent Vrystellingsdatum Vrystelling prys Notas
Bugatti 16.4 Veyron Pur Sang [33] September 2007 5 eenhede is gemaak.
Bugatti Veyron Fbg deur Hermès [34] Maart 2008 € 1,55 miljoen, belasting en vervoer uitgesluit [35] Hierdie model was beperk tot vier eenhede. 'N Veyron 16.4 Grand Sport is later in dieselfde opset vervaardig.
Bugatti 16.4 Veyron Sang Noir [36] Mei 2008 12 eenhede is gemaak.
Bugatti Veyron Bleu Centenaire [37] Maart 2009 Enig in sy soort.
Bugatti Veyron "Jean-Pierre Wimille" [38] September 2009
Bugatti Veyron "Achille Varzi" September 2009
Bugatti Veyron "Malcolm Campbell" September 2009
Bugatti Veyron "Hermann zu Leiningen" September 2009

Bugatti Veyron 16.4 Grand Sport (2009–2015) Wysig

Die top -weergawe van die Bugatti Veyron EB 16.4, genaamd die Bugatti Veyron 16.4 Grand Sport, is onthul tydens die Pebble Beach Concours d'Elegance in 2008. [39] [40] Dit het uitgebreide versterkings om te kompenseer vir die gebrek aan 'n standaard dak [41] en klein veranderinge aan die voorruit en lopende ligte. Twee verwyderbare toppe is ingesluit, die tweede 'n tydelike rangskikking wat na 'n sambreel gevorm is. Die topsnelheid met die hardtop in plek is dieselfde as die standaard coupé -weergawe, maar as die dak verwyder word, word dit beperk tot 369 km/h (229 mph) - en tot 130 km/h (81 mph) met die tydelike sagte dak. Die Grand Sport -uitgawe was beperk tot 150 eenhede, met die eerste 50 uitsluitlik vir geregistreerde Bugatti -kliënte. Produksie het in die tweede kwartaal van 2009 begin.

Spesiale uitgawes Redigeer

Naam Prent Vrystellingsdatum Vrystelling prys Notas
Bugatti Veyron 16.4 Grand Sport Sang Bleu [42] Augustus 2009 [43] Enig in sy soort.
Bugatti Veyron 16.4 Grand Sport L'Or Blanc [44] Junie 2011 €1,65 miljoen, belasting en vervoer uitgesluit Samewerking tussen Bugatti en die Royal Porcelain Factory in Berlyn.
Bugatti Veyron 16.4 Grand Sport "Dubai Motor Show 2011" Spesiale Uitgawe [45] November 2011 €1,58 miljoen, belasting en vervoer uitgesluit Bekendgestel met 'n horisontale kleursplitsing met 'n heldergeel omhulsel in sigbare swart koolstof (insluitend swart getinte wiele), sitplekke in geelkleurige leerbekleedsel met swart stiksels, middelkonsole in swart koolstof, paneelbord, stuurwiel en ratwisseling van swart leer met geel stiksel. [46] Die motor is toe weer op die 2012 motorskou in Katar vertoon.
Bugatti Veyron 16.4 Grand Sport "Dubai Motor Show 2011" Spesiale Uitgawe November 2011 €1,74 miljoen, belasting en vervoer uitgesluit Aangebied in 'n tweekleurige horisontale kleursplitsing bestaande uit sigbare blou koolstof, geraam in gepoleerde, geanodiseerde aluminium.
Bugatti Veyron 16.4 Grand Sport "Dubai Motor Show 2011" spesiale uitgawe November 2011 € 1,74 miljoen, belasting en vervoer uitgesluit Kom in die nuut ontwikkelde groen koolstofveseltoon met gepoleerde aluminium.
Bugatti Veyron 16.4 Grand Sport Bernar Venet [47] Desember 2012 [48] Enig in sy soort.

Bugatti Veyron 16.4 Super Sport, World Record Edition (2010–2011) Wysig

Die Bugatti Veyron 16.4 Super Sport is 'n vinniger, kragtiger weergawe van die Bugatti Veyron 16.4. Produksie was beperk tot 30 eenhede. Die Super Sport het verhoogde enjinkraglewering van 1 200 pk (883 kW 1 184 pk) by 6 400 rpm en 'n maksimum wringkrag van 1 500 N⋅m (1 106 lb⋅ft) by 3 000–5 000 rpm en 'n hersiene aërodinamiese pakket. [49] Die Super Sport is so vinnig as 431.072 km/h (267.856 mph) gery, wat dit die vinnigste produksie-padmotor ter wêreld maak ten tyde van sy bekendstelling [5] [50] [51] hoewel dit elektronies is beperk tot 415 km/h (258 mph) om die bande teen ontbinding te beskerm. [49]

Die Bugatti Veyron 16.4 Super Sport World Record Edition is 'n weergawe van die Bugatti Veyron 16.4 SuperSport. Dit is beperk tot vyf eenhede. Dit het 'n oranje karrosseriedetail, oranje wiele en 'n spesiale swart blootgestelde koolstofbak. Die elektroniese limiter word ook met hierdie weergawe verwyder. [52]

Die model is in 2010 by The Quail onthul, gevolg deur die 2010 Monterey Historic Races by Laguna Seca, en die Pebble Beach Concours d'Elegance 2010. [53]

Topspoed -wêreldrekord wysig

Op 4 Julie 2010, James May, 'n televisie -aanbieder op BBC Two se televisieprogram Hoogste rat, het die Veyron Super Sport op Volkswagen se Ehra-Lessien (naby Wolfsburg, Duitsland) hoëspoedtoetsbaan teen 417,61 km/h (259,49 mph) gery. Later die dag het Bugatti se amptelike toetsbestuurder Pierre Henri Raphanel met die Super Sport -weergawe van die Veyron op dieselfde baan gery om die topsnelheid van die motor te bepaal. Met verteenwoordigers van die Guinness Book of Records en die Duitse tegniese inspeksie -agentskap (TÜV) byderhand, het Raphanel om die groot ovaal in beide rigtings geslaag en 'n gemiddelde maksimum snelheid van 431,072 km/h (267,856 mph) behaal, en sodoende die titel teruggeneem van die SSC Ultimate Aero TT as die vinnigste produksievoertuig van alle tye. [12] Die 431.072 km/h -punt is bereik deur die gemiddelde van die Super Sport se twee toetslopies, die eerste wat 427.933 km/h (265.905 mph) en die tweede 434.211 km/h (269.806 mph) bereik het. [54] [55]

Toe die rekord gesertifiseer is, was die publiek reeds bekend dat die motor van die motor elektronies beperk sou word tot 415 km/h (258 mph). Tog, na 'n navraag deur die Sunday Times Jaime Strang, PR -direkteur van Guinness, is op 5 April 2013 aangehaal: "Omdat die motor se snelheidsbeperking gedeaktiveer is, was hierdie wysiging teen die amptelike riglyne. Gevolglik is die voertuig se rekord op 431.072 km/h nie meer geldig nie." Op 10 April 2013 is op sy webwerf geskryf: "Guinness World Records wil bevestig dat Bugatti se rekord nie gediskwalifiseer is nie, die rekordkategorie word tans hersien."

Op 15 April 2013 is Bugatti se spoedrekord bevestig: "Na 'n deeglike oorsig wat met 'n aantal eksterne kundiges gedoen is, kondig Guinness World Records graag die bevestiging aan van Bugatti se rekord van vinnigste produksiemotor wat deur die Veyron 16.4 SuperSport behaal is. Die fokus van die hersiening was ten opsigte van wat 'n wysiging van 'n motor se standaardspesifikasie kan inhou. [56] [57] [58]

Bugatti Veyron 16.4 Grand Sport Vitesse (2012–2015) Wysig

Die Bugatti Veyron 16.4 Grand Sport Vitesse is 'n top -weergawe van die Veyron Super Sport. Die enjin in die Vitesse -variant het 'n maksimum drywing van 1.200 PS (883 kW 1.184 pk) by 6.400 rpm en 'n maksimum wringkrag van 1.500 N⋅m (1.100 lb⋅ft) by 3.000-5.000 rpm. Hierdie syfers laat die motor in 2,6 sekondes van stilstaan ​​tot 100 km/h (62 mph) versnel. Op normale paaie is die Vitesse elektronies beperk tot 375 km/h (233 mph).

Die Vitesse is die eerste keer by die 2012 Geneefse Motorskou [59] [60] en later by die 2012 Beijing Motorskou [61] en die 2012 São Paulo Motorskou onthul. [62]

Spesiale uitgawes Redigeer

'n Aantal spesiale uitgawes van die Vitesse is gemaak:

  • Die World Record Car (WRC) -uitgawe was beperk tot 8 eenhede, debuteer in 2013 en verkoop vir € 1,99 miljoen. [63][64][65]

In 2013 het Bugatti 'n reeks Vitesse vervaardig wat toegewy is aan renlegendes, waaronder Jean-Pierre Wimille [71] [72] Jean Bugatti, [73] [74] Meo Costantini, [75] en Ettore Bugatti. [76]

Al ses modelle in die Legend-reeks is beperk tot drie voertuie: [77]

Naam Prent Vrystellingsdatum Vrystelling prys Notas
Bugatti Legend "Jean-Pierre Wimille" [78] 24 Julie 2013
Bugatti Legend "Jean Bugatti" [79] 9 September 2013 € 2,28 miljoen, belasting en vervoer uitgesluit
Bugatti Legend "Meo Costantini" [80] 5 November 2013 € 2,09 miljoen, belasting en vervoer uitgesluit Hierdie model herinner aan die Bugatti Type 35. Een van die drie vervaardigde modelle, die enigste Amerikaanse motor, is in Augustus 2020 op die Bonhams Quail-veiling verkoop vir $ 1,750,000 dollar. premie. [81]
Bugatti Legend "Rembrandt Bugatti" [82] [83] 3 Maart 2014 € 2,18 miljoen, belasting en vervoer uitgesluit Rembrandt Bugatti was die broer van die maatskappystigter Ettore en een van die belangrikste beeldhouers van die 20ste eeu.
"Black Bess" Legend Vitesse [84] [85] 10 April 2014 € 2,15 miljoen, belasting en vervoer uitgesluit Hierdie model herinner aan die beroemde Bugatti Type 18 "Black Bess".
Bugatti Legende "Ettore Bugatti" [86] 7 Augustus 2014 € 2,35 miljoen, belasting en vervoer uitgesluit Hierdie model gaan terug na die Bugatti Type 41 Royale.

Rekords wysig

'N Bugatti Veyron 16.4 Grand Sport Vitesse wat deur die Chinese renjaer Anthony Liu op Volkswagen se bewysveld in Ehra-Lessien bestuur is, het die vinnigste oop motor geword met 'n topsnelheid van 408,84 km/h (254,04 mph). [64]

Na die wêreldrekordpoging het dr. Wolfgang Schreiber, president van Bugatti Automobiles SAS, gesê: "Toe ons die Vitesse bekendstel, het ons die topsnelheid vir oop ry tot 375 km/h vasgestel. Tog kon ons nie los nie die idee om die 400 km/h -merk ook met hierdie motor te bereik. Die feit dat ons daarin geslaag het om 408,84 km/h te bereik, is vir my 'n opwinding, en dit bevestig weereens dat Bugatti die leier is wat tegnologie betref die internasionale motorbedryf. " Die bestuurder, Anthony Liu, beweer: "Selfs by sulke hoë snelhede bly dit ongelooflik gemaklik en stabiel. Met 'n oop dak kan jy die geluid van die enjin regtig ervaar, maar selfs teen hoër snelhede het ek nie deur die wind gekompromitteer nie. almal." [63]

Basiese spesifikasies [4] [5]
Uitleg en liggaamstyl Middelmotor, vierwielaangedrewe, tweedeurs coupé/targa-top Basisprys Standaard (Coupé), Grand Sport (Roadster):
€ 1,225,000 (£ 1,065,000 US $ 1,700,000)
Super Sport (Coupé), Grand Sport Vitesse (Roadster):
€1 912 500 ( £1 665 000 VS$2 700 000 )
Verbrandingsmotor 8,0 liter W16, 64v 2xDOHC vierwielaangedrewe petrolenjin Verplasing van enjin
en maks. krag
7 993 cc (487,8 cu in)
Standaard (Coupé), Grand Sport (Roadster):
736 kW (987 pk 1 001 PS) by 6 000 rpm
Super Sport (Coupé), Grand Sport Vitesse (Roadster):
883 kilowatt (1,201 PS 1,184 pk) by 6 400 rpm
Optrede
Standaard, Grand Sport Super Sport, Grand Sport Vitesse
Vinnigste spoed 408,47 km/h (253,81 mph) [87] 431,072 km/h (267,856 mph) 415 km/h (258 mph) beperk [55]
0–100 km/h (62 mph) 2.46 sekondes [88] [89]
0–200 km/h (124 mph) 7,3 sekondes [90] [91] 6,7 sekondes [92] [93]
0–300 km/h (186 mph) 16,7 sekondes [90] [91] 14.6 sekondes [92] [93]
0–400 km/h (249 mph) 55.6 sekondes [91] 40 sekondes [ aanhaling nodig ] (beraam) [ deur wie? ]
Staande kwartmyl (402 m) 10.1 sekondes [94] 9,7 sekondes [92]
Staande myl (1609 m) 25,9 sekondes teen 204,4 mph [95] 23,6 sekondes [92]
Rem vanaf 100 km/h (62 mph) 31,4 m [90] [92]
0–300–0 km/h 27.8 sekondes [96] 22.5 sekondes [92]
0–200–0 mph 25,6 sekondes [92]
Sywaartse versnelling ? 1.4 g [92]
Brandstofverbruik [97]
EPA stadsbestuur 8 myl per Amerikaanse gallon (29 L/100 km 9,6 mpg- imp) EPA snelweg ry 14 myl per Amerikaanse liter (17 l/100 km 17 mpg- imp)
Top spoed brandstofverbruik 3 myl per Amerikaanse gallon (78 L/100 km 3,6 mpg-imp), of 1,4 U.S. gal (5,3 L 1,2 imp gal) per minuut

Vanaf 6 Augustus 2014 [update] is 405 motors wêreldwyd vervaardig en aan kliënte afgelewer, met bestellings wat reeds geplaas is vir nog 'n 30. Bugatti sou tot einde 2015 300 coupés en 150 roadsters lewer. [98 ] Die produksie beloop 450 eenhede in 'n tydperk van meer as 10 jaar. Die finale produksievoertuig, 'n Grand Sport Vitesse getiteld "La Finale" (Die laaste een), is vanaf 5–15 Maart 2015 by die Geneefse Motorskou vertoon. [99]

Naam Eenhede gemaak
Veyron 16.4 252
Groot sport 58
Super Sport 48
Grand Sport Vitesse 92
Totaal 450

In 2008 het dr Franz-Josef Paefgen, destydse uitvoerende hoof van Bugatti, bevestig dat die Veyron teen 2012 deur 'n ander luukse model vervang sal word. [100] In 2011 het die nuwe uitvoerende hoof, Wolfgang Dürheimer, onthul dat die maatskappy beplan om twee modelle te vervaardig in die toekoms-die een 'n sportmotoropvolger van die Veyron, die ander 'n limousine bekend as die Bugatti 16C Galibier, wat later gekanselleer is, aangesien Bugatti later aan 'n opvolger van die Veyron gewerk het, wat die Bugatti Chiron geword het. [101]

Die opvolger van die Veyron is in konsepvorm as die Bugatti Vision Gran Turismo by die Frankfurtse motorskou in September 2015 onthul.

’n Getoonde weergawe van die radikaal-gestileerde Vision Gran Turismo-konsepmotor, wat nou die Chiron genoem word, het by die Geneefse Motorskou in Maart 2016 verskyn. Produksie het in 2017 begin en sal tot 500 eenhede beperk word.

Jaar Eenhede verkoop
2005 5 [102]
2006 44 [102]
2007 81 [103]
2008 71 [104]
2009 50 [104]
2010 40 [105]
2011 38 [106] 1
2012 31 [107]
2013 47 [108]
Totaal 407 ISI

Hoogste rat Redigeer

Al drie voormalige aanbieders van die gewilde BBC -motorprogram Hoogste rat het die Veyron aansienlike lof gegee. Hoewel aanvanklik skepties was dat die Veyron ooit vervaardig sou word, het Jeremy Clarkson later die Veyron verklaar as "die grootste motor ooit gemaak en die grootste motor wat ons ooit in ons leeftyd sal sien", en dit vergelyk met Concorde en S.S. Groot Brittanje. Hy het opgemerk dat die produksiekoste van 'n Veyron £ 5 miljoen beloop, maar vir slegs £ £ 1 miljoen aan kliënte verkoop is. Volkswagen het die motor bloot as 'n tegniese oefening ontwerp. James May het die Veyron as “ons Concorde-oomblik” beskryf. Clarkson -toets het die Veyron van Alba in Noord -Italië na Londen gery in 'n wedloop teen May en Richard Hammond wat die reis in 'n Cessna 182 -vliegtuig onderneem het.

'N Paar aflewerings later ry May met die Veyron by die VW -toetsbaan en haal dit tot sy topsnelheid van 407,16 km/h (253,00 mph). In reeks 10 jaag Hammond die Veyron teen die Eurofighter Typhoon en verloor. Hy het ook die motor in reeks 13 gehardloop teen 'n McLaren F1 wat deur The Stig gery is in 'n 1,6 km lange dragren in Abu Dhabi. Die kommentaar fokus op Bugatti se "ongelooflike tegniese prestasie" teenoor die "nie-gizmo" renne van die F1. Terwyl die F1 vinniger van die lyn af was en voor was totdat albei motors teen ongeveer 200 km/h gery het, het die Bugatti sy mededinger van 200 tot 300 km/h ingehaal en die oorwinnaar behaal. Hammond het gesê dat hy nie die Veyron se lanseerbeheer gebruik het om die wedloop interessanter te maak nie.

Die Veyron het ook die toekenning vir "Car of the Decade" in gewen Hoogste rat se prysuitreiking einde 2010. Clarkson het gesê: "Dit was 'n motor wat net die reëlboek herskryf het, 'n wonderlike stuk ingenieurswese, 'n ware Concorde-oomblik". Toe die standaardweergawe in 2008 getoets is, het dit nie die top van die rondetyd -ranglys bereik nie, met 'n tyd van 1: 18.3, wat vermoedelik te wyte was aan die motor se aansienlike gewigstekort teenoor die ander motors na bo. In 2010 het die SuperSport-weergawe die vinnigste tyd ooit van 1:16.8 behaal (die Gumpert Apollo S onttroon, vervang deur die Ariel Atom V8 in 2011), [109] asook na 'n geverifieerde gemiddelde topspoed van 431 km/h geneem. (268 km / h) deur Raphanel op die program, [110] en neem dan weer sy posisie in as die vinnigste produksiemotor ter wêreld. [111] [112] [113]

Martin Roach Edit

In 2011, Martin Roach se boek Bugatti Veyron: A Quest for Perfection – Die storie van die grootste motor ter wêreld [114] het die standpunt ingeneem dat die motor nou so bekend geword het dat dit effektief 'n bona fide celebrity is. Die boek volg die skrywer daarvan terwyl hy probeer om die motor op te spoor en te bestuur, onderweg onderhoude met hoofontwerpers, toetsbestuurders en die president van Bugatti.

Gordon Murray wysig

Tydens sy ontwikkelingsperiode het die ontwerper van die McLaren F1, Gordon Murray, in die Britse motorblad gesê Evo: "Die nutteloosste oefening op die planeet moet hierdie vierwielaangedrewe, duisend-perdekrag Bugatti wees." Maar nadat hy dit bestuur het, het hy dit "'n reuse prestasie" genoem. [115]

Murray was beïndruk met die Veyron se enjin en ratkas nadat hy een gery het Pad en baan tydskrif. Hy het ook die styl daarvan geprys: "Die styl is 'n wonderlike mengsel van klassieke krommes en meganiese rande en elemente - dit moet verseker dat die motor nog jare daarna lyk en dus 'n toekomstige klassieke kan word." [116]


Suidelike Navorsingsstasie

Pyemotes parviscolyti Cross & Moser is slegs foneties aan Pityophthorus bisulcatus Eichhoff dit val alle stadiums van hierdie insek aan behalwe die volwassene. Wyfies, wat min of geen gif bevat, prooi op ander skolitiede as galerye oorvleuel. Mannetjies kopieer met wyfies van Pyemotes ventricosus Newport en omgekeerd, maar slegs mans van die moedersoort kom voor. Kopulasie met Pyemotes scolyti Oudeman 's was nie suksesvol nie.

  • Aanhaling: Moser, John c. Cross, E.A. 1971. Biologie van Pyemotes parviscolyti (acarina: pyemotidae). Entomophaga, Vol.16 (4): 367-379
  • Geplaas datum: 20 April 2006
  • Gewysigde datum: 22 Augustus 2006

Drukpublikasies is nie meer beskikbaar nie

In 'n voortdurende poging om fiskaal verantwoordelik te wees, sal die Suidelike Navorsingstasie (SRS) nie meer harde kopieë van ons publikasies vervaardig en versprei nie. Baie SRS -publikasies is teen koste beskikbaar by die Government Printing Office (GPO). Elektroniese weergawes van publikasies kan afgelaai, gedruk en versprei word.


Inhoud

Kategorieë Redigeer

Daar is drie kategorieë (strategieë) van weddenskapverskansing: "konserwatiewe" weddenskapverskansing, "gediversifiseerde" weddenskapverskansing en "aanpasbare muntstukke."

Konserwatiewe weddenskapverskansing Wysig

In konserwatiewe weddenskapverskansing verlaag individue hul verwagte fiksheid in ruil vir 'n laer afwyking in fiksheid. Die idee van hierdie strategie is dat 'n organisme 'altyd veilig moet speel' deur dieselfde suksesvolle strategie met 'n lae risiko te gebruik, ongeag die omgewingstoestande. [6] 'n Voorbeeld hiervan is 'n organisme wat koppelaars produseer met 'n konstante eiergrootte wat moontlik nie optimaal is vir enige omgewingstoestand nie, maar die laagste algehele afwyking tot gevolg het. [6]

Gediversifiseerde verbintenisverskansing Wysig

In teenstelling met konserwatiewe weddenskapverskansing, vind gediversifiseerde weddenskapverskansing plaas wanneer individue hul verwagte fiksheid in 'n gegewe jaar verlaag terwyl dit ook die variansie van oorlewing tussen die nageslag verhoog. Hierdie strategie gebruik die idee om nie al u eiers in 'n mandjie te sit nie. [6] Individue wat hierdie strategie implementeer belê eintlik in verskeie verskillende strategieë gelyktydig, wat lei tot lae variasie in langtermyn sukses. Dit kan gedemonstreer word deur 'n koppelaar eiers van verskillende groottes, elk optimaal vir een potensiële omgewing van die nageslag. Alhoewel dit beteken dat nageslag wat vir 'n ander omgewing gespesialiseer is, minder geneig is om tot volwassenheid te oorleef, beskerm dit ook teen die moontlikheid dat geen nageslag tot die volgende jaar sal oorleef nie. [6]

Aanpasbare muntstukke draai

'N Persoon wat hierdie tipe weddenskapverskansing gebruik, kies watter strategie om te gebruik, gebaseer op 'n voorspelling van hoe die omgewing sal wees. Organismes wat hierdie vorm van verbintenisverskansing gebruik, maak hierdie voorspellings en kies jaarliks ​​strategieë. Byvoorbeeld, 'n organisme kan van jaar tot jaar kloue van verskillende eiergroottes produseer, wat die variasie in die nageslag se sukses tussen kloue verhoog. [6] In teenstelling met konserwatiewe en gediversifiseerde weddenskapverskansingstrategieë, is aanpasbare muntstukke nie gemoeid met die vermindering van die variasie in fiksheid tussen jare nie.

Om vas te stel of 'n weddenskap-allel bevoordeel word, moet die langtermyn geskiktheid van elke alleel vergelyk word. Veral in hoogs veranderlike omgewings waar wedverskansing waarskynlik sal ontwikkel, word fiksheid op lang termyn die beste gemeet met behulp van die meetkundige gemiddelde [7], wat vermenigvuldigend is in plaas van additief soos die rekenkundige gemiddelde. Die meetkundige gemiddelde is baie sensitief vir klein waardes. Selfs seldsame gevalle van nulgeskiktheid vir 'n genotipe lei tot 'n verwagte geometriese gemiddelde van nul. Dit maak dit geskik vir omstandighede waar 'n enkele genotipe veranderlike fiksheid kan hê, afhangende van die omgewingsomstandighede.

Daar word verstaan ​​dat wedverskansing 'n manier is om op omgewingsverandering te reageer. [8] Aanpassings waarmee organismes in wisselende omgewingstoestande kan oorleef, bied 'n evolusionêre voordeel. Alhoewel 'n verbintenisverskermende eienskap moontlik nie optimaal is vir enige omgewing nie, word dit swaarder as die voordele van hoër fiksheid in verskillende omgewings. Daarom is weddenskapverskansingsallele geneig om in meer veranderlike omgewings bevoordeel te word. Om 'n weddenskapverskanser-alleel te laat versprei, moet dit lank genoeg in die tipiese omgewing deur genetiese drywing voortduur sodat alternatiewe omgewings, waarin die weddenskapverskanser 'n voordeel het bo genotipes wat by die vorige omgewing aangepas is, kan plaasvind. By baie daaropvolgende omgewingswisselinge kan seleksie die allel na fixasie laat vaar. [9]

'N Algemene voorbeeld wat gebruik word by die beskrywing van verbintenisverskansing, is die vergelyking van die rekenkundige en meetkundige fiksheid tussen spesialis- en verbintenisverskansingsgenotipes. [10] [11] Die onderstaande tabel toon die relatiewe geskiktheid van vier fenotipes in 'goeie' en 'slegte' jare en hul onderskeie middele as 'goeie' jare 75% van die tyd en 'slegte' jare 25% van die tyd voorkom .

The good year specialist has the highest fitness during a good year but does very poorly during a bad year, while the reverse is true for a bad year specialist. The conservative bet hedger does equally well in all years and the diversified bet hedger in this example uses the two specialist strategies each 50% of the time they perform better than the conservative bet hedger in good years, but worse during a bad year.

In this example, fitness is approximately equal within the specialist and bet hedger strategies, with the bet hedgers having a significantly higher fitness than the specialists. While the good year specialist' has the highest arithmetic mean, the bet hedging strategies are still preferred due to their higher geometric mean.

It is also important to realize that the fitness of any strategy is dependent on a large number of factors, such as the ratio of good to bad years and its relative fitness between good and bad years. Small changes in the strategies or environment having a large impact on which is optimal. In the above example, the diversified bet hedger outweighs the conservative bet hedger if it uses the good year specialist strategy more often. In contrast, if the relative fitness of the good year specialist was 0.35 in a bad year, it becomes the optimal strategy.

Prokarya Edit

Experiments in bet hedging using prokaryotic model organisms provide some of the most simplified views of the evolution of bet hedging. As bet hedging involves a stochastic switching between phenotypes across generations, [12] prokaryotes are able to display this phenomenon quite nicely due to their ability to reproduce quickly enough to track evolution in a single population over a short period of time. This rapid rate of reproduction has allowed for the study of bet hedging in labs through experimental evolution models. These models have been used to deduce the evolutionary origins of bet hedging.

Within prokarya, there are a multitude of bet hedging examples. In one example, the bacterium Sinorhizobium meliloti stores carbon and energy in a compound known as poly-3-hydroxybutyrate (PHB) in order to withstand carbon-deficient environments. When starved, S. meliloti populations begin to display bet hedging by forming two non-identical daughter cells during binary fission. The daughter cells display either low PHB levels or high PHB levels, which are better suited to short and long-term starvation, respectively. It has been reported that the low-PHB must compete effectively for resources in order to survive, whereas the high-PHB cells can survive for over a year without food. In this example, the PHB phenotype is being ‘bet-hedged’, as the survivability of the offspring largely depends on their environment, where only one phenotype is likely to survive under specific conditions. [13]

Another example of bet hedging arises in Mycobacterium tuberculosis. In a given population of this bacteria, persister cells exist with the ability to arrest their growth, which leaves them unaffected by dramatic changes to the environment. Once the persister cells grow to form another population of its species, which may or may not be antibiotic resistant, they will produce both cells with normal cell growth and another population of persisters to continue this cycle as the case may be. The ability to switch between the persister and normal phenotype is a form of bet-hedging. [14]

Prokaryotic persistence as a method of bet hedging is thus of importance to the field of medicine due to bacterial persistence. Because bet hedging is designed to produce genetically diverse offspring randomly in order to survive catastrophe, it is difficult to develop treatments for bacterial infections, as bet hedging may ensure the survival of its species within its host, heedless to the antibiotic.

Eukarya Edit

Eukaryotic bet hedging models, unlike prokaryotic models, tend to be used to study more complex evolutionary proceces. In the context of eukaryotes, bet hedging is best used as a way to analyze complex environmental influences affecting the selective pressures underlying the principle of bet hedging. However, because Eukarya is a broad category, this section has been subdivided into kingdoms Animalia, Plantae, and Fungi.

Vertebrate Wysig

In example, West Atlantic salmon (Salmo salar) have been hypothesized to have major histocompatibility complex (MHC)-dependent mating systems, which have been shown in other species to be important for determining disease resistance among offspring. Namely, there is evidence that selection for increased MHC diversity is a strong influence on mate choice, where it is thought that individuals are more likely to mate with individuals whose MHC is less similar to their own in order to produce variable offspring. In accordance with the bet hedging model, it has been found that the reproductive success of mating pairs of Atlantic salmon is environmentally dependent, where certain MHC constructs are only advantageous under specific environmental circumstances. Thus, this supports the evidence that MHC diversity is crucial for the long-term reproductive success of the parents, as the tradeoff for an initial decrease in short-term reproductive fitness is mediated by the survival of a few of their offspring in a variable environment. [15]

A second example among vertebrates is the marsupial species Sminthopsis macrour, which use a torpor strategy in order to reduce their metabolic rate to survive environmental changes. Reproductive hormone cycles have been shown to mediate the timing of torpor and reproduction, and in mice have been shown to mediate this process entirely, heedless to the environment. In the marsupial species, however, an adaptive coin flipping mechanism is employed where neither torpor nor reproduction are affected by manipulation of hormones, suggesting that this marsupial species makes a more active decision about when to use torpor that is better-suited to the uncertain environment in which it lives. [16]

Invertebrate Wysig

Many invertebrate species are known to exhibit various forms of bet hedging. Diaptomus sanguineus, an aquatic crustacean species found in many ponds of the Northeast United States, is one of the most well-studied examples of bet hedging. This species uses a form of diversified bet hedging called germ banking, in which emergence timing among offspring from a single clutch is highly variable. This reduces the potential costs of a catastrophic event during a particularly vulnerable time in offspring development. In Diaptomus sanguineus, germ banking occurs when parents produce dormant eggs prior to annual environmental shifts that yield increased risk for developing offspring. For example, in temporary ponds, Diaptomus sanguineus production of dormant eggs peaks just before the annual dry season in June when ponds levels decrease. In permanent ponds, dormant egg production increases in March, just before an annual increase in feeding activity of sunfish. [17] This example demonstrates that germ banking may take different forms within a species depending on the environmental risk presented. Bet hedging through variable egg hatching patterns are seen in other crustaceans as well. [18] [19]

Invertebrate bet-hedging has also been observed in the mating systems of some species of spider. Female sierra dome spiders (Linyphia litigiosa) are polyandrous, mating with secondary males in order to compensate for uncertainty regarding the quality of the primary mate. Primary male mates are considered to be of higher fitness than secondary males, as primary mates must overcome intrasexual fighting prior to mating with a female, while secondary male mates are chosen through female choice. Scientists believe multiple paternity has evolved in response to virgin insemination by low quality secondary male mates who have not undergone selection through intrasexual fighting. Females have developed a mechanism for sperm precedence to retain control over offspring paternity and increase offspring fitness. Further examination of female genitalia has supported this hypothesis. The sierra dome spider exhibits this behavior as a form of genetic bet hedging, reducing the risk of producing low quality offspring and contracting venereal disease. [20] This form of bet hedging is notably different than most other forms of bet hedging, as it has not arisen in response to environmental conditions, but rather it has arisen as a result of the species mating system.

Fungi Edit

Bet hedging is employed in fungi similarly to bacteria, but in fungi, it is more complex. This phenomenon is beneficial to fungi, but in some cases, it has harmful effects on humans, illustrating that bet hedging has clinical importance. One study suggests that bet hedging may even contribute to the failure of chemotherapy in cancer due to mechanisms similar to that of bet hedging used in fungi. [21]

One way fungi use bet hedging is by displaying different colony morphologies when grown on agar plates. [22] This variation allows for colonies with different morphologies, including resistances that allow them to survive, to thrive and reproduce in different conditions or environments. As a result, fungal infections may be more difficult to treat if bet hedging is involved. For example, pathogenic strains of yeast like Candida albicans of Candida glabrata using this strategy will resist treatments. These fungi are known to cause an infection known as candidiasis.

While bet hedging in fungi is important, not much is known about the mechanisms for the different strategies employed by different species. Researchers have studied S. cerevisiae to determine the mechanism of bet hedging in this species. [22] It was determined that in S. cerevisiae, variation exists in the distribution of growth rates among yeast micro-colonies and that slow growth is a predictor of resistance to heat. Tsl1 is one gene that was determined as a factor in this resistance. The abundance of this gene was shown to correlate with heat and stress resistance, and thus survival of the yeast micro-colonies under harsh conditions by using bet hedging. This illustrates that by using bet hedging, pathogenic strains of this yeast that are harmful to humans are more difficult to treat.

A group of researchers studied another way bet hedging is used by looking at the ascomycete fungus Neurospora crassa. [23] It was observed that this species produces ascospores with variation in their dormancy because non-dormant ascospores can be killed by heat, but dormant ascospores will survive. The only con is that it will take longer for the dormant ascopores to be germinated.

Plantae Edit

Plants provide simple examples for studying bet hedging in wildlife, allowing for field studies but without as many confounding factors as animals. Studying closely related plant species can help us understand more about the circumstances under which bet hedging evolves.

The classic example of bet hedging, delayed seed germination, [1] has been extensively studied in desert annuals. [24] [25] [26] One four-year field study [24] found that populations in historically worse (drier) environments had lower germination rates. They also found a large range of germination dates and flexibility in germination for drier populations when exposed to rain, a phenomenon known as phenotypic plasticity. Other studies of desert annuals [25] [26] have also found a relationship between temporal variation and lower germination rates. One of these studies [26] also found the density of seeds in the seed bank to affect germination rates.

Bet hedging through a seed bank has also been implicated in the persistence of weeds. One study [27] of twenty weed species showed that the percentage of viable seeds after 5 years increased with soil depth, and germination rates decreased with soil depth (although specific numbers varied between species). This indicates that weeds will engage in bet hedging at higher rates in circumstances where the costs of bet hedging are lower.

Collectively, these findings do provide evidence for bet hedging in plants, but also show the importance of competition and phenotypic plasticity that simple bet hedging models often ignore.

Archaea Edit

Thus far, research on bet hedging involving species in the domain Archaea hasn't been easily accessible.

Viruses Edit

Bet hedging has been used to explain the latency of Herpes viruses. The Varicella Zoster Virus, for instance, causes chickenpox at first infection and can cause shingles many years after the original infection. The delay with which shingles emerges has been explained as a form of bet hedging. [28]


Neurowetenskap

Neuroscience, the study of neuron and brain function, is among the most rapidly-expanding of biological disciplines. Neuroscientists in the Department of Molecular Biology focus primarily on systems, computational, and cellular questions, with an emphasis on the neural basis of learning and behavior. Specific projects address questions in visual processing, decision-making, social communication, working memory, spatial navigation, autism, and immune protein function in synapses. We ask these questions at levels ranging from single neurons and synapses to behaving animals.

Department neuroscientists use a variety of powerful technologies ranging from genetics and cell biology of model organisms such as mice, worms, flies to multi-photon imaging of neurons in action. A major strength of the community is the use of "NIH BRAIN Initiative"-style tools for manipulating and mapping brain circuitry. Examples of such methods include in vivo optical observation of brain activity using multiphoton microscopy detailed quantitative analysis of animal behavior computational analysis of complex data viral-assisted gene delivery to manipulate, monitor, and trace neural circuits the use and refinement of genetically encoded activity sensors and transgenic organisms. These tools are used to help understand how information in the brain is represented (neural coding) and changes over time (neural dynamics) to support complex behaviors. Neuroscience faculty in Molecular Biology are jointly appointed to the Princeton Neuroscience Institute, which houses the Bezos Center for Neural Circuit Dynamics, a center that focuses on the development and application of microscopy imaging techniques for measuring neural circuit dynamics in the functioning brain.


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Weischer M, Nordestgaard BG, Pharoah P et al (2012) CHEK2*1100delC heterozygosity in women with breast cancer associated with early death, breast cancer-specific death, and increased risk of a second breast cancer. J Clin Oncol 30:4308–4316

Lianos GD, Zoras O, Roukos DH (2013) Beyond BRCA1/2: polygenic, ‘polyfunctional’ molecular circuitry model to predict breast cancer risk. Biomark Med 7(5):675–678

Copson E, Eccles B, Maishman T, Gerty S, Stanton L, Cutress RI, Altman DG, Durcan L, Simmonds P, Lawrence G, Jones L, Bliss J, Eccles D (2013) POSH Study Steering Group: prospective observational study of breast cancer treatment outcomes for UK women aged 18–40 years at diagnosis: the POSH study. J Natl Cancer Inst 105:978–988

Collins LC, Marotti JD, Gelber S, Cole K, Ruddy K, Kereakoglow S, Brachtel EF, Schapira L, Come SE, Winer EP, Partridge AH (2012) Pathologic features and molecular phenotype by patient age in a large cohort of young women with breast cancer. Breast Cancer Res Treat 131:1061–1066

Gnerlich JL, Deshpande AD, Jeffe DB, Sweet A, White N, Margenthaler JA (2009) Elevated breast cancer mortality in women younger than age 40 years compared with older women is attributed to poorer survival in early-stage disease. J Am Coll Surg 208:341–347

Keegan TH, DeRouen MC, Press DJ, Kurian AW, Clarke CA (2012) Occurrence of breast cancer subtypes in adolescent and young adult women. Breast Cancer Res 14:R55

Azim HA Jr, Nguyen B, Brohée S et al (2015) Genomic aberrations in young and elderly breast cancer patients. BMC Med 15(13):266

Azim H, Azim HA Jr (2013) Targeting RANKL in breast cancer: bone metastasis and beyond. Expert Rev Anticancer Ther 13:195–201

Ribnikar D, Ribeiro JM, Pinto D et al (2015) Breast cancer under age 40: a different approach. Curr Treat Options Oncol 16(4):16

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Christopher S. Fraser

Querido, J. B., Sokabe, M., Kraatz, S., Gordiyenko, Y., Skehel, J. M., Fraser, C. S., and Ramakrishnan, V. Structure of a human 48S translational initiation complex. Wetenskap. 2020 Sep 4369(6508):1220-1227.

Sokabe, M, and Fraser, C. S. Toward a Kinetic Understanding of Eukaryotic Translation. Cold Spring Harb. Perspektief. Biol. 2019 Feb 111(2).

Avanzino, B. C., Fuchs, G., and Fraser, C. S. Cellular cap-binding protein, eIF4E, promotes picornavirus genome restructuring and translation. Proc Natl Acad Sci U S A. 2017 Sep 5114(36):9611-9616.

Sokabe, M., and Fraser, C. S. ATP-dependent restructuring of the 40S subunit decoding site during mRNA recruitment. Proc Natl Acad Sci U S A. 2017 Jun 13114(24):6304-6309.

García-García, C., Frieda, K. L., Feoktistova, K., Fraser, C. S., and Block, S. M. Factor-Dependent Processivity in the Human eIF4A DEAD-box Helicase. Wetenskap. 2015 Jun 26348(6242):1486-8.

Sokabe, M., and Fraser, C. S. Human Eukaryotic Initiation Factor 2 (eIF2)-GTP-Met-tRNAi Ternary Complex and eIF3 Stabilize the 43S Preinitiation Complex. J Biol Chem . 2014 Nov 14289(46):31827-36.

Özeş AR, Feoktistova K, Avanzino BC, Baldwin EP, Fraser CS. Real-time fluorescence assays to monitor duplex unwinding and ATPase activities of helicases. Nat Protoc. 2014 Jul9(7):1645-61.

Villa, N., Do, A., Hershey, J. W., and Fraser, C. S. Human eukaryotic initiation factor 4G (eIF4G) binds to eIF3c, -d, and –e to promote mRNA recruitment to the ribosome. J. Biol. Chem. 2013 Nov 15288(46):32932-40.

Feoktistova, K., Tuvshintogs, E., Do, A., and Fraser, C. S. Human eIF4E promotes mRNA restructuring by stimulating eIF4A helicase activity. Proc Natl Acad Sci U S A. 2013 110 (33) 13339-13344.

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Ozeş AR, Feoktistova K, Avanzino BC, Fraser CS. Duplex Unwinding and ATPase Activities of the DEAD-Box Helicase eIF4A Are Coupled by eIF4G and eIF4B. J Mol Biol. 2011: 412, 674-687

Fraser, C. S., Hershey, J. W., and Doudna, J. A. The pathway of hepatitis C virus mRNA recruitment to the human ribosome. Nat. Struktuur. Mol. Biol. 2009 Apr16(4):397-404.

Fraser, C. S., Berry, K. E., Hershey, J. W., and Doudna, J. A. eIF3j is located in the decoding center of the human 40S ribosomal subunit. Mol. Sel. 2007 Jun 2226(6):811-9.


16.4: Overview - Biology

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The central dogma of molecular biology states that information encoded in DNA is transferred to RNA, which then directs the synthesis of proteins, based on these instructions.

First, in the process of transcription, DNA is used as a template to synthesize messenger RNA, mRNA, which represents a copy of the coding strand. Except the thymidines are replaced uracils.

Next, in the process of translation in eukaryotes, mRNA travels to a ribosome. Here, codons, groups of three nucleotides, in the mRNA, bind to complementary sequences on transfer RNA, tRNA molecules. Each of which is attached to a particular amino acid, depending on the specific codon.

For example, the codon CCA binds to a tRNA attached to proline, while AGC binds to a tRNA attached to serine. In this way, the genetic code specifies the order in which the amino acids are arranged in the resulting polypeptide. Polypeptides are often then further processed to become functional proteins.

14.2: The Central Dogma

Oorsig

The central dogma of biology states that information encoded in the DNA is transferred to messenger RNA (mRNA), which then directs the synthesis of protein. The set of instructions that enable the mRNA nucleotide sequence to be decoded into amino acids is called the genetic code. The universal nature of this genetic code has spurred advances in scientific research, agriculture, and medicine.

RNA Is the Missing Link between DNA and Proteins

In the early 1900s, scientists discovered that DNA stores all the information needed for cellular functions and that proteins perform most of these functions. However, the mechanisms of converting genetic information into functional proteins remained unknown for many years. Initially, it was believed that a single gene is directly converted into its encoded protein. Two crucial discoveries in eukaryotic cells challenged this theory: First, protein production does not take place in the nucleus. Second, DNA is not present outside the nucleus. These findings sparked the search for an intermediary molecule that connects DNA with protein production. This intermediary molecule, found in both the nucleus and the cytoplasm, and associated with protein production, is RNA.

During transcription, RNA is synthesized in the nucleus, using DNA as a template. The newly-synthesized RNA is similar in sequence to the DNA strand, except thymidine in DNA is replaced by uracil in RNA. In eukaryotes, this primary transcript is further processed, removing the protein non-coding regions, capping the 5&rsquo end and adding a 3&rsquo poly-A tail, to create mRNA that is then exported to the cytoplasm.

The Rules for Interpreting the mRNA Sequence Constitute the Genetic Code

Translation occurs at ribosomes in the cytoplasm, where information encoded in the mRNA is translated into an amino acid chain. A set of three nucleotides codes for an amino acid and these triplets are called codons. The set of rules that outline which codons specify a particular amino acid make up the genetic code.

The Genetic Code Is Redundant

Proteins are created from 20 amino acids in eukaryotes. Combining four nucleotides in sets of three provides 64 (4 3 ) possible codons. This means that it is possible that individual amino acid can be encoded by more than one codon. The genetic code is said to be redundant or degenerate. Often, but not always, codons that specify the same amino acids differ only in the third nucleotide of the triplet. For example, the codons GUU, GUC, GUA, and GUG all represent the amino acid valine. However, AUG is the only codon that represents the amino acid methionine. The codon AUG is also the codon where protein synthesis starts and is therefore called the start codon. Redundancy in the system minimizes the harmful effects of mutations. A mutation (i.e., change) at the third position of the codon might not necessarily result in a change of the amino acid.

The Genetic Code Is Universal

With a few exceptions, most prokaryotic and eukaryotic organisms use the same genetic code for protein synthesis. This universality of the genetic code has enabled advances in scientific research, agriculture, and medicine. For instance, human insulin can now be manufactured on a large scale in bacteria. This is done using recombinant DNA technology. Recombinant DNA consists of genetic material from different species. Genes encoding human insulin are joined with bacterial DNA and inserted into a bacterial cell. The bacterial cell performs transcription and translation to produce the human insulin encoded in the recombinant DNA. The resulting human insulin is used to treat diabetes.

Smith, Ann and Kenna Shaw. &ldquoDiscovering the relationship between DNA and protein production.&rdquo Natuuropvoeding 1 no. 1 (2008):112. [Source]

Ralston, Amy and Kenna Shaw. &ldquoReading the genetic code.&rdquo Natuuropvoeding 1 no. 1 (2008):120. [Source]


Kyk die video: Biologie: GRUNDLAGEN DER MOLEKULARGENETIK DVD. Vorschau (Augustus 2022).