Category Archives: DNA

DNA Diagnostics Center has served the U.S. and locations around the world since 1995. The tests available in and around Houston have been recommended by hospitals, doctors, and even popular TV shows, such as Maury and Dr. Phil. From simple paternity tests to evidence in high-profile cases, DDC's results are 100% accurate, and are completed in as little as one day.

Also, clients can expect the following benefits:

All samples are tested 2x, assuring the results are accurate.

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Test procedures are in concordance with AABB regulations and the U.S. Department of State. In fact, DDC's testing laboratory has been accredited by the AABB.

DNA test consultants are on hand to take your call. They can assess your needs and determine the most suitable test. A vast network of collection sites enables clients around the world to have easy access to our services. It is also the most affordable access to DNA testing you'll find. We offer:

Individual DNA Testing

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Prenatal paternity tests are non-invasive. Being easy and hassle free, these are viable even by the 9th week of pregnancy, eliminating the guesswork early on.

We maintain a large network of collection sites throughout the U.S., so even clients in different states are provided with the most reliable and swift service. This means petitioners and beneficiaries can be located either within or near Houston and elsewhere in the United States.

Review the local resources on our site to determine collection locations by zip code. There are over 2,500 pickup locations within the continental United States. Call 1-800-613-5768 to speak with a consultant about test options and to arrange the most convenient location to collect samples.

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Houston DNA Testing Services | Paternity Tests

Tento lnek pojednv onositelce genetick informace. Ometabolickm onemocnn pojednv lnek dna.

Deoxyribonukleov kyselina, bn oznaovan DNA (z anglickho deoxyribonucleic acid, esky zdka iDNK), je nukleov kyselina, nositelka genetick informace vech organism svjimkou nkterch nebunnch, unich hraje tuto lohu RNA (nap. RNA viry). DNA je tedy pro ivot nezbytnou ltkou, kter ve sv struktue kduje a bukm zadv jejich program a tm peduruje vvoj a vlastnosti celho organismu. Ueukaryotickch organizm (jako nap. rostliny a ivoichov) je DNA hlavn slokou chromatinu, smsi nukleovch kyselin a protein, a je uloena zejmna uvnit bunnho jdra, zatmco uprokaryot (nap. bakterie a archea) se DNA nachz voln vcytoplazm.

DNA je biologick makromolekula polymer v podob etzce nukleotid. Nukleotidy jsou vdy sloeny zcukru deoxyribzy, fosftov skupiny a jedn ze ty nukleovch bz. Informan funkci maj prv bze, jimi me bt adenin (A), guanin (G), cytosin (C) nebo thymin (T). Prvn dv pat mezi puriny, zbyl mezi tzv. pyrimidiny. Dv vlkna DNA se asto spojuj a vytvej dvouroubovici, jej tvar je tak slavn, e se stal kulturn ikonou modern doby.[1] Dvouroubovici DNA tvo dv navzjem spleten roubovice, kad mc opanm smrem (jsou antiparaleln). Mezi protilehlmi bzemi obou vlken se vytvej vodkov mstky, a to ti mezi guaninem a cytosinem nebo dva mezi adeninem a thyminem. Existuj i jin zpsoby uspodn etzc, vymykajc se tradin pedstav dvouroubovice.

Deoxyribonukleov kyselina je stedem zjmu vdc nejen z biologickch obor a byly vyvinuty promylen techniky jej izolace, separace, barven, sekvenovn, uml syntzy a manipulace s n pomoc metod genovho inenrstv. Vechny tyto postupy jsou dleit i pro lkae, kriminalisty i evolun biology DNA je zsadnm materilem v diagnostice nemoc, testech otcovstv, pi vyetovn zloin, pprav plodin s novmi vlastnostmi i teba hledn pbuzenskch vztah mezi organismy.

Deoxyribonukleov kyselina byla popsna roku 1869, kdy vcarsk lka Friedrich Miescher zkoumal sloen hnisu znemocninch obvaz. Zjader blch krvinek ptomnch vtomto hnisu zskal jist mnostv nukleovch kyselin, kter souhrnn nazval nuklein.[2] Na potku 20. stolet Phoebus Levene rozpoznal, e DNA se skld zcukr, fosft a bz.[3]

Ofunkci DNA toho dlouho nebylo moc znmo. Prvn dkaz oroli DNA vpenosu genetick informace pinesl vroce 1944 Averyho-MacLeodv-McCartyho experiment, kter provedli Oswald Avery spolen sColinem MacLeodem a Maclynem McCartym. Sri pokus stransformac pneumokok zjistili, e DNA je genetickm materilem bunk.[4] Dal dkaz pinesl vroce 1952 Hersheyho-Chaseov experiment.

Patrn nejslavnjm milnkem ve vzkumu DNA bylo odhalen jej trojrozmrn struktury. Sprvn dvouroubovicov model poprv pedstavili vroce 1953 vasopise Nature James D. Watson a Francis Crick, pozdj laureti Nobelovy ceny.[5] Vychzeli pitom zrentgenov difrakn analzy, kterou orok dve provedli Rosalind Franklinov a Raymond Gosling a publikovali ve stejnm sle Nature. Dal lnek vtomto vydn pedloil iMaurice Wilkins.[6] Vroce 1957 pedloil vt dob ji slavn Crick srii pravidel, kter se oznauj jako centrln dogma molekulrn biologie a popisuj vztahy mezi DNA, RNA a proteiny.[7] Orok pozdji slavn Meselsonv-Stahlv experiment umonil poznat zpsob replikace DNA vbukch.[8] Genetick kd rozlutili na potku 60. let Har Gobind Khorana, Robert W. Holley a Marshall Warren Nirenberg.[9]

Ptomnost nukleovch kyselin, tedy DNA a RNA, je spolenou vlastnost vech znmch pozemskch organism. Veker ivot je zaloen na koexistenci tchto nukleovch kyselin s blkovinami, nicmn nen zcela jasn, jak se vztah mezi DNA a blkovinami vyvinul. Podle nkterch hypotz nejprve existovaly blkoviny a a nsledn vznikly nukleov kyseliny, nicmn nejvce pznivc m zejm v souasnosti pedstava, e prapvodn ltkou byla nukleov kyselina, kter byla schopna biologick evoluce. Podle teorie RNA svta vak hlavn roli hrla nejprve spe RNA a teprve poslze pejala hlavn roli DNA.[10] Doklady ve prospch takovch hypotz jsou vak vdy nepm, protoe nejsou k dispozici dostaten star vzorky DNA. ivot vznikl ji ped nkolika miliardami let, jene u po nkolika destkch tisc let kles mnostv DNA na setinu pvodnho stavu. Studie v asopise Nature z let 2000 a 2002 nicmn popisuj nlez a 450 milion let starch vzork bakteriln DNA uchovanch v solnch krystalech,[11][12] dle existuje i ada dalch, vce nebo mn spolehlivch studi.

Stavbu DNA je mono zkoumat na nkolika rovnch. Poad nukleotid vlinernm dvouvlkn je zleitost tzv. primrn struktury. Sten vlkna do dvouroubovice se oznauje jako sekundrn struktura DNA. Konen pod tzv. tercirn strukturou se rozum obvykle nadroubovicov vinut, kter usnaduje kondenzaci DNA.

DNA vlastn nen nic jinho ne velmi dlouh linern etzec nukleotid. Napklad uvnit kadho virionu planch netovic se nachz DNA odlce 193 mikrometr, kruhov DNA uEscherichia coli m dlku 1600 mikrometr (1,6mm), lidsk genom je rozloen do 23 linernch molekul DNA (v haploidnm stavu) ocelkov dlce 1 metru.[13] Nukleotid je zkladn stavebn jednotkou vech molekul DNA; existuj pitom tyi zkladn typy nukleotid, je se vDNA pirozen vyskytuj. Tyto tyi nukleotidy (dATP, dGTP, dCTP, dTTP) se navzjem li typem piven nukleov bze, j me bt pedevm adenin, guanin, cytosin i thymin.[pozn. 1] Dleit je, e kad nukleotid m ti dleit stavebn sousti:

Primrn struktura DNA se d znzornit jako linern ada nukleotid nebo teba jako ada psmen, kter odpovdaj duskatm bzm vtchto nukleotidech. Dle je dleit, e DNA je smrovan (direkcionalizovan), tzn. daj se jednoznan odliit oba konce. Smr vlken se oznauje prv podle orientace deoxyribzy vnm, tedy: smr 3'5' a opan smr 5'3'. Podle konvence se poad nukleotid zapisuje smrem 5'3' (nap. TACGGACGGG AGAAGCGCGC GGGCGGGCCG je prvnch 30 z3675 nukleotid tvocch pepisovanou st genu pro lidsk alfa-tubulin[15]).

Vroce 2011 se objevila zprva oexistenci bakteri GFAJ-1, kter dajn ve sv DNA obsahuje msto fosftovch skupin arseninany.[16] Hypotza byla definitivn vyvrcena v r. 2012.[17][18][19]

Deoxyribonukleov kyselina (DNA) me existovat jako samostatn jednovlknov molekula (tzv. ssDNA), nicmn velmi asto vytv vcevlknov struktury, kter jsou sloen znkolika etzc spojench vodkovmi mstky. Vodkov mstky jsou jednm ztyp pomrn slabch vazebnch interakc, mezi dvma i vce vlkny DNA jich vak me vzniknout obrovsk mnostv; vsledn vcevlknov struktura tak je pomrn stabiln. Typickou formou takovho vcevlknovho uspodn DNA je dvouroubovice, notoricky znm molekula DNA (pipomnajc stoen ebk) tvoen dvma linernmi etzci. Aby vznikla pravideln struktura svelkm mnostvm vodkovch mstk, je douc, aby se vedle sebe vpli ebku vyskytovaly vdy urit nukleov bze, kter spolu ve sprvnm prostorovm uspodn vytv nkolik vodkovch mstk. Vtypickm ppad (ne vak vdy) se nukleov bze spojuj navzjem sodpovdajc bz podle jednoduchho kle:

Jedn se otzv. komplementaritu bz, zn vychz vzjemn komplementarita obou vlken DNA. Vdy je na urit pozici vmolekule jeden nukleotid zdvojice a vprotjm vlkn druh znich. Takto se uchovv vkadm zvlken tat informace, i kdy jedno z vlken je negativem vlkna druhho podle jednoho vlkna je mon piazenm komplementrnch bz vytvoit vlkno druh. Pomr AT a GC pr vmolekule DNA je velmi rzn: tzv. obsah GC se pohybuje ubakteri od 25 do 75%, usavc vrozmez 3946%.[20]

Existuje cel ada dalch monost, jak pomoc vodkovch mstk sprovat bze, nebo atom schopnch podlet se na vzniku vodkovch vazeb je na molekulch purin ipyrimidin cel ada. Samostatnou kapitolou je tzv. hoogsteenovsk provn pojmenovan podle Karsta Hoogsteena, kter je v60. letech 20. stolet jako prvn popsal.[21] Jinou monost je tzv. wobble provn, kter umouje sporn rozeznvn kodon pomoc tRNA molekul. Pi wobble provn me napklad guanin vytvet vazbu suracilem; nkdy je rekrutovn inosin, jen m velmi obecn vazebn schopnosti a je schopen vzat se na C, Aa U.[22]

Vdrtivm procentu ppad se DNA za bnch podmnek uchovv ve form pravotoiv dvouroubovice. Dvouroubovice DNA je tvoena dvma vlkny DNA, kter se obt kolem spolen osy a interaguj spolu. Vlkna jsou tzv. antiparaleln, tzn. smuj opanmi smry[23] zatmco jedno vlkno meme jednm smrem popsat jako 5'-3', druh je ve stejnm smru 3'-5'. sla 3' a 5' oznauj sla uhlku na deoxyribze, na kter se upnaj fosftov skupiny vcukr-fosftov koste DNA. Mezi bzemi vrmci jednoho patra dvouroubovice plat pravidla Watson-Crickovsk komplementarity.

Existuje nkolik tzv. heliklnch forem (konformac) DNA, kter se li celou adou parametr. Typick Watson-Crickovsk pravotoiv dvouroubovice (tzv. B-DNA) je nicmn zcela pevaujc a ostatn formy (zejmna pravotoiv A-DNA a levotoiv Z-DNA) se sice mohou vyskytovat ivpodmnkch iv buky, nicmn spe vzcn a jen za specifickch okolnost.[24][25][26]

Vobecnm povdom DNA tvo dvouroubovici, nicmn existuj ijin zpsoby uspodn. Nkter se vyskytuj ivbukch (in vivo), jin jsou spe laboratorn zleitost. Mnohdy se vyuv neobvyklch provacch mst na molekulch bz. To je ppad tzv. G-kvartet, tyvlknovch sek DNA vtelomerickch oblastech chromozom, vnich do kruhu pruj tyi guaninov bze.[27] Co se te trojroubovice DNA,[28][29] mon doasn vznik pi tzv. crossing-overu;[30] laboratorn me bt trojvlknov struktura pipravena nap. zvlken poly(A) a polydeoxy(U).[31]

DNA se tak me vtvit a vznikaj nap. tvlknov i tyvlknov spojen. Vnkterch ppadech dvouroubovicov DNA na jednom svm konci lokln denaturuje a na uvolnn konce se pipoj tet etzec vprosted buky by tato struktura mohla vznikat pi crossing-overu, pokud nedolo kreplikaci vjednom zgenom.[32] Jindy takto vlastn denaturuj dv dvouroubovice a vzjemn se komplementrn pilo, m vznik tyvlknov spojen. Vppad crossing-overu se jedn oznm Hollidayv spoj, kter umouje vlastn vmnu homolognch vlken.[33] Pi replikaci DNA i pi oprav DNA mohou vtven vznikat tak. Vlaboratoi nicmn vznikaj jet mnohem fantastitj prostorov struktury DNA byly vyrobeny nap. krychle i osmistn sloen cel pouze zDNA molekul. Tyto a dal syntetick struktury DNA jsou vcentru zjmu DNA nanotechnolog.[1]

Genom, tedy souhrn DNA vbuce, nen pouhou zmt dvouroubovicov DNA na vych rovnch je mon pozorovat komplikovan vinut a etn interakce sbunnmi blkovinami. Zcela typick je tzv. nadroubovicov vinut (supercoiling), tedy dodaten roubovicov vinut ji existujc dvouroubovice.[34] Nadroubovicov vinut se d zjednoduen pedstavit tak, e drme vkad ruce jeden zobou konc provzku a postupn na jednom konci provzek kroutme. Vznikl napt se opt uvoln (relaxuje) jen tehdy, pokud uvolnme jednu ruku. Dvouroubovice je vak stoen ji ve svm relaxovanm stavu (jedna otka kadch cca 10 pr bz), a tak meme rozliit, zda se nadroubovice vine stejnm smrem, jako dvouroubovice (tzv. pozitivn supercoiling), nebo smrem opanm (negativn supercoiling, uvoluje DNA). Nadroubovicov vinut m celou adu dleitch funkc a regulanch rol;[35] vdnm ppad se nejedn pouze oanomlii ve struktue.

DNA se vbuce dle organizuje do mikroskopicky pozorovatelnch tvar znmch jako chromozomy. Ubakteri je zejm systm kondenzace DNA do (obvykle jedinho) chromozomu ponkud mn propracovan a nap. uEscherichia coli zahrnuje nkolik protein, kter jsou schopn udrovat nadroubovicov vinut a vytvet ostr ohyby vlkna DNA.[36]Eukaryotick organismy, jako je teba lovk, maj velmi komplikovan sbalenou DNA. Souvis to sdlkou jejich DNA nap. lidsk genom m na dlku dva metry, pitom bunn jdro m na dlku nkolik mikrometr. Dvouvlkno DNA se nejprve nabaluje na bazick proteiny znm jako histony; DNA nabalen na osm histon vytv tzv. nukleozom, a tak na tto rovni DNA vypad jako ada korlk (nukleozom) na provzku (DNA). Tyto korlky se vak obvykle jet st do 30 nanometr tlust roubovice.[37] Na vzniku chromozom se podl jet vy rovn sbalen DNA, kter jsou vak mn prostudovan a vznikaj jen vuritch fzch bunnho cyklu.

DNA je polymern sloueninou svysokou molrn hmotnost. Molrn hmotnost zvis na dlce DNA a zhruba plat, e skadm nukleotidem stoup molrn hmotnost o330g/mol, vppad dvouvlknov DNA na jeden pr bz pipad asi 650g/mol.[38] Deoxyribonukleov kyselina je zporn nabit (dky fosforenanovm skupinm), a je tedy polrnho charakteru. Dky tomu je rozpustn ve vod, naopak vethanolu se sr (nebo dochz kvyvzn zpornch nboj).[39] Po vysren m DNA blou barvu.[40] Izolovan DNA zaujm dvouroubovicov uspodn, to je vak mon rozruit vprocesu denaturace. Typicky se denaturace provd zvenm teploty, ale denaturaci zpsobuje inzk iontov sla roztoku nebo siln zsadit prosted. Naopak kysel prosted nen vhodn, protoe dochz khydrolze glykosidovch vazeb mezi cukrem a bz.[41] DNA absorbuje vUV oblasti sabsorpnm maximem pi vlnov dlce 260 nm. Pi denaturaci DNA se absorbance vtto oblasti zvyuje tomuto jevu se k hyperchromn efekt.[42] Je to dno tm, e na absorpci se v nejvt me podlej bze DNA, kter jsou v dsDNA "schovan" uvnit dvouroubovice. Po denaturaci dochz k "obnaen" bz, kter tak mohou lpe absorbovat UV zen.

Poloas rozpadu DNA in dle studia kosternch nlez asi 521 let.[43] DNA je povaovna za stabiln molekulu, co vynikne zejmna pi srovnn s RNA jakoto druhou vznamnou nukleovou kyselinou. V molekule DNA nen na 2' uhlku OH skupina u RNA tam tato reaktivn skupina je a zpsobuje ni stabilitu RNA.[44] DNA se v laboratoi dlouhodob skladuje pi 20 nebo 70C, kde vydr i nkolik let. Pi teplot 4C v TE pufru vydr nkolik tdn.[45] Uvnit tl ivch organism vak DNA mus snet i pomrn vysok teploty, a pesto vydr. Krajnm ppadem jsou hypertermofiln organismy, kter ij i pi teplotch kolem 100C. Jejich DNA el jak riziku denaturace, tak i termodegradaci (rozpadu pevnch chemickch vazeb). Pesto ij a mimo opravnch mechanism k tomu zejm pispv i nadroubovicov vinut a tak optimln iontov sloen cytoplazmy.[46]

Pro DNA jsou vak dle typick inkter vlastnosti, kter ji do jist mry odliuj od bnch chemickch ltek. Vbuce je napklad mon replikovat DNA, tedy vytvet jej kopie. Vcemn kad bunn dlen vyaduje zmnoen genetick informace, aby j vkad buce bylo stle konstantn mnostv. Vprbhu procesu se oddl etzce matesk DNA a oba slou jako nvod (tzv. templt) pro tvorbu druhch vlken vrmci obou nov vznikajcch dvouroubovic. Ty jsou nsledn napl tvoeny pvodn DNA a napl nov dosyntetizovan cel proces je semikonzervativn. Kdalm zajmavm vlastnostem DNA vbukch pat monost opravovat DNA, co jet dle vylepuje (u tak pomrn precizn) penos genetick informace.[47] Bylo by mono najt mnostv dalch pozoruhodnch vlastnost DNA, vesms probhajcch vbuce za pomoci specilnch enzym.

DNA je nositelkou genetick informace vech ivch organism vpravm slova smyslu, ale imnoha vir. VDNA je zapsna sekvence vech blkovin a penesen je genetickou informac podmnna existence vech biomolekul a bunnch struktur (kjejich tvorb jsou poteba blkoviny).[48] Schopnost ukldat a penet genetickou informaci je jednou zfundamentlnch vlastnost ivota.[48] Bez DNA buky vydr t jen omezenou dobu; napklad lidsk erven krvinky pi svm zrn vyvrhuj jdro, a protoe pak nejsou schopn vyrbt nov blkoviny a udrovat buku, jsou po nkolika mscch pokozeny a mus se zobhu odstraovat.[49] Nkter viry jsou sice schopn uchovvat svj genetick materil vpodob RNA (tzv. RNA viry), jene RNA genomy nepodlhaj opravnm mechanismm a rychle mutuj, a proto maj limitovanou velikost.[50] ivot, tak jak ho znme, je proto zvisl na DNA.

Konkrtn uloen DNA vbuce zvis na pslunosti organismu kjedn zdvou zkladnch skupin organism. Bakterie a archea (souhrnn prokaryota) maj DNA obvykle uloenu voln vcytoplazm. Obvykle vznik pouze jist jadern oblast, tzv. nukleoid. Mimo to ada bakteri vlastn imal kruhov molekuly DNA, tzv. plazmidy, kter umouj mimo jin horizontln vmnu genetick informace. Zbyl organismy, tedy nap. lovk, ale irostliny, ivoichov i prvoci, maj DNA uloenu pedevm vbunn jde. Dle vak se DNA nachz vnkterch eukaryotickch organelch, jmenovit vmitochondrich a vplastidech, pokud je buka vlastn (jev zvan mimojadern ddinost).

Informace nesen sekvenc nukleotid vDNA se oznauje jako genetick informace. Na kad nukleotidov pozici se nachz jedna ze ty bz (A, C, G i T), co znamen, e sekvence odlce n me nabvat 4n stav.[51] Pro DNA dlouhou pouhch 10 nukleotid existuje tedy teoreticky 410= 1048576 kombinac. Lidsk genom (souhrn lidsk jadern DNA) pitom obsahuje 3,1 miliardy (pr) bz.[52] Nejvy informan hodnota se pitom vgenomu objevuje vmstech, kde sdl tzv. geny, kter zaznamenvaj informaci pro tvorbu RNA a potamo ivech blkovin. Informace pro tvorbu blkovin je zaifrovna pomoc tpsmennho kdu znmho jako genetick kd. Kad trojici bz vDNA toti uprotein-kdujcch gen odpovd urit aminokyselina. Aminokyseliny jsou zkladn stavebn kameny blkovin, take je vlastn genetick informace jakmsi nvodem na vrobu blkovin. Genetick informace je uplatovna podle tzv. centrlnho dogmatu molekulrn biologie. DNA je nejprve pepisovna vRNA (obvykle tzv. messenger RNA), nae je tato RNA pouita jako vzor pro tvorbu blkovin. Prvn zmnn krok se jmenuje transkripce, druh translace.

Velk st genomu mnoha organism vak nen soust dnho genu a dokonce se ani nepepisuje v RNA. Role tto tzv. nekdujc DNA je v mnoha ppadech neznm; nkdy vak pomh regulovat spoutn a vypnn okolnch gen.[53] Velk st nekdujc DNA dle souasn rovn znalost nem dnou konkrtn funkci a oznauje se prost jako junk (odpadn) DNA.[54] st tto odpadn DNA vak podle vsledk projektu ENCODE ve skutenosti kduje rzn krtk regulan RNA; celkem se odhaduje, e 1020% genomu m dky tmto RNA vznamnou regulan funkci. V tsnm okol tchto regulanch sekvenc se tak podle ENCODE celkem nachz a 95% lidskho genomu.[55][56]

Vcel ad ppad je douc izolovat zbunk i zvirovch partikul jejich DNA. Existuje samozejm cel ada metod extrakce DNA, nicmn uvech je nutn zskat dostaten mnostv biologickho materilu, uvolnit DNA a oddlit ji znadmolekulrnch struktur, nae je nutn vzorek peistit a ppadn zahustit.[57] Dleitm krokem je uvolnn DNA zbunk, kter se uivoinch bunk provd pomoc detergent (povrchov aktivnch isticch ltek), je rozruuj membrny. Ubunk sbunnou stnou je to komplikovanj a je nutn nasadit teba lysozymy (na bakteriln bunnou stnu) i mechanickou degradaci. Co se te peiovn bunnch extrakt, obvykle je nutn se zbavit blkovin, kter pedstavuj hlavn kontaminaci vzork. Je mon pout protezy, ale mnohdy se proteiny sr fenolem a chloroformem, zatmco nukleov kyseliny zstanou vroztoku a je mon je pak vysret teba ethanolem.[58]

Po izolaci DNA nsleduje asto separace (oddlen) poadovanch druh molekul. Me bt douc oddlen teba plazmid od genomov DNA bakteri, co se dl pomrn jednodue centrifugac pi vhodn nastavench parametrech, obvykle pomoc denaturace a nsledn renaturace.[58] Pro jemnj rozdlovn podle velikosti ipodle topologie DNA se asto pouv elektroforza na agarzovm (i vppad velmi malch molekul na polyakrylamidovm) gelu. Vppad extrmn velkch fragment DNA se uv tzv. pulzn gelov elektroforza. Zgelu je mon nsledn DNA pevst na nitrocelulzovou membrnu pomoc tzv. Southernova penosu. Dal metodou dlen DNA je centrifugace vhustotnm gradientu, obvykle vgradientu chloridu cesnho tato metoda oddluje zejmna fragmenty, je se li zastoupenm bz (obsahem GC).[59]

Byl vyvinut nespoet zpsob, jak obarvit DNA a to jak pmo vbuce, tak iDNA izolovanou vlaboratornm skle. Pouvaj se asto vlaboratoch ve chvli, kdy je nutn nap. velektroforetickm gelu i pmo ve fixovan buce zvraznit DNA. Ke znmm takovm barvivm pat (bez logick nslednosti): SYBR Green, YOYO-1, TOTO-1, TO-PRO, SYTOX Green, ale iklasick ethidiumbromid a propidiumjodid, akridinov oran, rzn Hoechst barviva i teba DAPI.[60] Kvelmi specifickm barvcm metodm pat fluorescenn in situ hybridizace (FISH), kter umouje navzn fluorescennch sond na konkrtn sekvenci DNA.[61]

Sekvenovn DNA je souhrnn termn pro biochemick metody, jimi se zjiuje poad nukleovch bz vsekvencch DNA.[62] Prv poad bz je princip zakdovn genetick informace, a proto je vcentru zjmu biolog. Pvodn a po dlouh lta pevaujc metodou bylo tzv. Sangerovo sekvenovn, kter vyuv speciln chemicky upravench nukleotid, je jsou pomoc DNA polymerzy zaazovny suritou pravdpodobnost do prodluujc se DNA tm blokuj dal polymeraci a vsledn produkt je mon detekovat pomoc elektroforzy. Vsouvislosti se snahou zrychlit a zlevnit sekvenovac proces byla vyvinuta cel ada sekvenanch metod nov generace. K tm pat nap. pyrosekvenovn a pbuzn metody. Studie Zhang et al. 2011 uvd pt modernch metod, je jsou komern dostupn: Roche GS-FLX 454 (454 sekvenovn), Illumina (Solexa), ABI SOLiD, Polonator G.007 a Helicos HeliScope.[63]

Existuje icel ada postup, jak si pipravit i namnoit konkrtn molekulu DNA. Jednou zmonost je chemick syntza DNA, pi n dochz ksestavovn krtkch oligonukleotid, a to postupnm azenm nukleotid za sebou. Vtypickm ppad vak ji je urit mnostv DNA kdispozici a je douc ho pouze zmnoit tak, aby vechny kopie mly pokud mono totonou sekvenci. To se asto dl bu pomoc klonovn DNA nebo metodou polymerzov etzov reakce.[64]

Vdeck pokrok v oblasti genetiky zpsobil boom v mnoha oblastech lkask diagnostiky. Napklad v bakteriologii, virologii a parazitologii se uplatnily metody, je umouj v napaden tkni detekovat DNA pochzejc z mikroorganism, je tuto tk napadly. To se dl bu pomoc rznch DNA prb schopnch se specificky vzat na uritou sekvenci typickou pro danho parazita, nebo nap. cestou namnoen DNA pomoc polymerzov etzov reakce a nslednm sekvenovnm tm je mon zskat sekvenci DNA patogennch organism, j mikrobiologov srovnaj s databzemi patogennch kmen. Tyto pokroil molekulrn metody se uplatuj nap. pi identifikaci tko kultivovatelnch bakteri i pi urovn cel ady virovch i parazitrnch onemocnn.[65]

Soust diagnostick prce je vak i studium lidsk DNA uplatuje se napklad v rakovinn terapii[66] i pi diagnostice nkterch genetickch onemocnn. Sv msto ji molekulrn metody naly v prenatln diagnostice chorob, nap. ze vzorku plodov vody.[67] Dal testy se rutinn provd z kapky krve novorozenc. Testy DNA v rmci genetickho poradenstv vak dnes mohou pomoci i prm, je teprve dt plnuj. Je to vhodn tehdy, vyskytuje-li se v rodinn historii njak genetick onemocnn. Dnes jsou genetick testy dostupn vem zjemcm a je mon o sob zjistit celou adu informac od tch zejmch (barva o) pes rzn zajmavosti (atletick vlohy) a po vn daje (nchylnost k rakovin atp.).[68]

Nkter oblasti nap. lidsk jadern DNA jsou velmi promnliv a lovk od lovka se vnich tm vdy li. Ztohoto dvodu je DNA vkriminalistice a vforenznch vdch neocenitelnm zdrojem informac. Repetitivn sekvence znm jako VNTR i STR pat mezi ty nejastji studovan. Studium VNTR repetic vyaduje relativn velk mnostv DNA, a proto se vyuv zejmna tehdy, mme-li kdispozici vzorek krve (nap. utest otcovstv). Obvykle se testuj metodou RFLP (jen zkoum polymorfismus dlky restriknch fragment). Vkriminalistice naly vt vyuit tzv. STR (ili ~mikrosatelity). Pravdpodobnost, e dv osoby budou mt jednu STR oblast shodnou, je pro danou variantu nap. 1:83, co by nebylo pli pesvdiv, a proto se pouv obvykle 13 marker, kter se vyhodnocuj zvl a vzjemn pozitivn vsledek dvryhodnost testu mnohonsobn zvyuje. Prvn pouit DNA vkriminalistice se datuje do roku 1986 a dolo knmu vrmci soudnho zen vAnglii. Testovn STR oblast se vak dnes prosazuje ivurovn otcovstv.[69]

Vsouasnosti je lidstvo schopn provdt clen zmny vgenetick informaci (vpoad nukleotid vDNA) a ovlivovat tm nkter vlastnosti organism. Tyto tzv. genetick modifikace zpsobily revoluci vcel ad biotechnologickch odvtv a umouj nap. prmyslovou produkci hormon, srecch faktor pro hemofiliky, enzym uvanch vpotravinstv a nkterch vakcn. Vsledkem genetickho inenrstv jsou irzn transgenn plodiny, nap. ty odoln kherbicidm.[70] VEvropsk unii je zgeneticky modifikovanch plodin povolena pouze Bt kukuice,[71] kter nese gen cry pochzejc zpdn bakterie Bacillus thuringiensis. Tento gen zpsobuje, e je rostlina pro sv hmyz kdce jedovat.[72]

V neposledn ad se studium sekvenc DNA uplatuje v tdn organism podle jejich pbuznosti, tedy v oboru biologie znmm jako fylogenetika. Jednou z prvnch krk v tomto oboru byla v 60. letech studie, kter srovnvala sekvenci genu pro cytochrom c u rznch organism: vsledky jsou v podstat intuitivn, zatmco impanz m sekvenci tohoto genu s lovkem zcela shodnou a makak rhesus se li pouze jedinou nukleotidovou zmnou, ps gen pro cytochrom u se od lidskho genu li na 13 mstech a kvasinkov gen dokonce na 56 pozicch. Na zklad tchto informac si lze udlat obrzek o pbuzenskch vztazch mezi organismy. V souvislosti s rozmachem sekvenovn je dnes k dispozici obrovsk mnostv sekvenc DNA cel ady organism a k jejich analze se pouvaj rzn sofistikovan nstroje, jako napklad metoda parsimonie nebo metoda maximln pravdpodobnosti. Dnes je mono i odhadnout as, kter dl v evolun historii libovoln dva druhy metoda k tomu uvan opt pracuje se sekvencemi DNA a oznauje se jako molekulrn hodiny. Pomoc fylogenetickch pstup je mono odpovdat na celou adu dalch otzek, namtkou jak vztah maj neandertlci k dnenm lidem, jak se mezi jednotlivmi nemocnmi virus HIV a podobn.[73]

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DDC provides DNA testing services to all U.S. states and in countries worldwide. We can arrange separate appointments for each tested party,even those living in different states or countries.

Schedule your appointment today by calling our consultants at 1-800-613-5768 well arrange sample collection at a location most convenient for you.

New York State is well-served by DNA Diagnostic Centers 65 sample collection locations. Individuals and families have as much access in their local vicinities as anyone throughout the U.S. DDC is willing and able to arrange appointments located in or easily reached from most major cities in NY.

We can arrange an appointment for you that is either located in, or conveniently accessible from, one of these cities:

This page lists DDC's sample collection sites in New York and is updated on a regular basis. For the most updated information, please call us at 1-800-613-5768.

For paternity testing prices and ordering information please click here.

Clients in any of these localities can call for a free consultation. Experts provide advice on testing options and benefits to the client, based on their requirements. The most appropriate DNA test can be found by making one easy phone call.

Arranging for delivery and sample collection is a synch as well. Collection sites are listed on maps accessible through links to major cities on our website. Paternity testing locations, in New York City for example, are clearly labeled. This is also the case with locations in every state in the U.S.

Once we receive your DNA sample, results are available in as little as one day. Thats not all. All samples are tested twice to maximize accuracy and reliability.

Several DNA testing services are provided, so we can best meet clients needs.

- Relationship DNA Testing: If theres any doubt to the relationship between siblings, twins, grandparents/parents and children, then our trusted testing will verify the genetic relationships in question. - Paternity Testing: Legal and in-home paternity tests are available. You can order one for child support or other purposes, or for your own curiosity. Results are 100% accurate so definitive proof of biological relationships between a father and child is provided. In addition, non-invasive paternity tests are available to establish paternity as early as nine weeks into pregnancy. - Immigration DNA Testing: Biological relationships between petitioners and beneficiaries can be established through testing performed in our AABB accredited laboratory. We can arrange for samples to be collected at a U.S. Embassy or USCIS office in a foreign country. Well also send results to the clients preferred immigration office or their attorney.

Call 1-800-359-9465 for more details and the most updated information on available services and collection locations in New York State.

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All living things have a special genetic makeup that is unique to their species. Animals, plants, single-celled organisms, and even some viruses contain deoxyribonucleic acid, also called DNA, which contains these genes. They are responsible in creating new cells and for holding the blueprints of the organism. Currently, geneticists are studying DNA in order to understand how to fight certain diseases, and also to figure out how to artificially replicate DNA strands in order to create cells in a laboratory setting.

DNA is one of the most significant parts of any living organism. It makes up the building blocks of all individual creatures and is directly responsible for all the traits of a creature. Color, size, shape, and any deformations that may occur are all a result of the unique DNA strands that are formed when the organism is developing. Through DNA replication, cells can divide and tissue damage can be repaired. DNA is also allowing scientists to help find cures for many genetic diseases or conditions that are prevalent today. Some examples of these genetic diseases, which are results of faulty or mutated DNA, are Down's Syndrome and sickle-cell anemia.

A single strand of DNA features two base polymers, which are simply long strands of protein molecules, that run in different directions, but parallel to each other, never crossing. Between them are the mess of genetic material that creates the unique makeup of an individual. These are formed by sugar molecules, which are attached to bases, of which there are four different kinds. The bases are simple molecules that are responsible for creating pairs with sugars, which attach to make molecules. These combine in various ways over and over again to create the entire DNA blueprint. These structures are called chromosomes, which are duplicated when cells divide.

DNA holds all the genetic material that creates the genome of an organism. When cells divide, DNA is read by RNA strands and then replicated. The needed DNA strands then fuse together to create a copy of the original DNA strand. When this is done, new cells are created, which will then build new tissues and so on. This is the most important function of DNA as it is what allows the body to heal itself over time and also is the process that takes place during pregnancy to create a new member of a species.

Friedrich Miescher was the first person to successfully isolate DNA in 1869. This began the study of DNA, and in 1919 the next major discovery was found. It was then that Phoebus Levene discovered the sugars, bases, and phosphates in the DNA. Later, scientists began to discover how these basic units fit together to create a long strand that could be "read." As the strands were studied, scientists found that segments of them could be read to represent certain traits of organisms. In recent times, DNA has been studied for genetic engineering.

DNA has a telltale shape that is taught as part of basic scientific knowledge in school. It is the double helix shape, which consists of two long strips, the polymers, which run parallel to and twist around each other. Connected to either end of these polymers are long strands of genetic chromosomes. In humans, there are 46 chromosomes that are made up of base pairs of various sugar and base pairings. These all combine to make a single strand of DNA, of which there are many in an organism.

DNA fingerprinting can determine a child's father or identify suspects from crime scene samples. Because 99.9 percent of human DNA is identical,...

Before the 1980s, blood tests were the primary way to establish paternity when the father of a child was in question. Since...

DNA carries the central instructions for protein synthesis in the cell. DNA carries genes that are encoded and transferred to RNA molecules....

DNA testing, or genetic profiling, involves the analysis of an individual's skin, saliva, semen, blood, hair or other bodily material to learn...

A DNA fingerprint is a piece of DNA so distinct that it can prove a person's identity. These distinct areas can take...

In 1984, during a scientific experiment regarding the repeated core sequences in DNA, Sir Alec Jeffreys accidentally discovered DNA fingerprinting. Sir Jeffreys...

In chemistry, a polymer is a chemical compound formed by a sequence of repeated smaller units called monomers. Deoxyribonucleic acid (DNA) consists...

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What Is DNA? | eHow

Deoxyribonucleic Acid (DNA)

We all know that elephants only give birth to little elephants, giraffes to giraffes, dogs to dogs and so on for every type of living creature. But why is this so?

The answer lies in a molecule called deoxyribonucleic acid (DNA), which contains the biological instructions that make each species unique. DNA, along with the instructions it contains, is passed from adult organisms to their offspring during reproduction.

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In organisms called eukaryotes, DNA is found inside a special area of the cell called the nucleus. Because the cell is very small, and because organisms have many DNA molecules per cell, each DNA molecule must be tightly packaged. This packaged form of the DNA is called a chromosome.

During DNA replication, DNA unwinds so it can be copied. At other times in the cell cycle, DNA also unwinds so that its instructions can be used to make proteins and for other biological processes. But during cell division, DNA is in its compact chromosome form to enable transfer to new cells.

Researchers refer to DNA found in the cell's nucleus as nuclear DNA. An organism's complete set of nuclear DNA is called its genome.

Besides the DNA located in the nucleus, humans and other complex organisms also have a small amount of DNA in cell structures known as mitochondria. Mitochondria generate the energy the cell needs to function properly.

In sexual reproduction, organisms inherit half of their nuclear DNA from the male parent and half from the female parent. However, organisms inherit all of their mitochondrial DNA from the female parent. This occurs because only egg cells, and not sperm cells, keep their mitochondria during fertilization.

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DNA is made of chemical building blocks called nucleotides. These building blocks are made of three parts: a phosphate group, a sugar group and one of four types of nitrogen bases. To form a strand of DNA, nucleotides are linked into chains, with the phosphate and sugar groups alternating.

The four types of nitrogen bases found in nucleotides are: adenine (A), thymine (T), guanine (G) and cytosine (C). The order, or sequence, of these bases determines what biological instructions are contained in a strand of DNA. For example, the sequence ATCGTT might instruct for blue eyes, while ATCGCT might instruct for brown.

The complete DNA instruction book, or genome, for a human contains about 3 billion bases and about 20,000 genes on 23 pairs of chromosomes.

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DNA contains the instructions needed for an organism to develop, survive and reproduce. To carry out these functions, DNA sequences must be converted into messages that can be used to produce proteins, which are the complex molecules that do most of the work in our bodies.

Each DNA sequence that contains instructions to make a protein is known as a gene. The size of a gene may vary greatly, ranging from about 1,000 bases to 1 million bases in humans. Genes only make up about 1 percent of the DNA sequence. DNA sequences outside this 1 percent are involved in regulating when, how and how much of a protein is made.

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DNA's instructions are used to make proteins in a two-step process. First, enzymes read the information in a DNA molecule and transcribe it into an intermediary molecule called messenger ribonucleic acid, or mRNA.

Next, the information contained in the mRNA molecule is translated into the "language" of amino acids, which are the building blocks of proteins. This language tells the cell's protein-making machinery the precise order in which to link the amino acids to produce a specific protein. This is a major task because there are 20 types of amino acids, which can be placed in many different orders to form a wide variety of proteins.

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The Swiss biochemist Frederich Miescher first observed DNA in the late 1800s. But nearly a century passed from that discovery until researchers unraveled the structure of the DNA molecule and realized its central importance to biology.

For many years, scientists debated which molecule carried life's biological instructions. Most thought that DNA was too simple a molecule to play such a critical role. Instead, they argued that proteins were more likely to carry out this vital function because of their greater complexity and wider variety of forms.

The importance of DNA became clear in 1953 thanks to the work of James Watson, Francis Crick, Maurice Wilkins and Rosalind Franklin. By studying X-ray diffraction patterns and building models, the scientists figured out the double helix structure of DNA - a structure that enables it to carry biological information from one generation to the next.

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Scientist use the term "double helix" to describe DNA's winding, two-stranded chemical structure. This shape - which looks much like a twisted ladder - gives DNA the power to pass along biological instructions with great precision.

To understand DNA's double helix from a chemical standpoint, picture the sides of the ladder as strands of alternating sugar and phosphate groups - strands that run in opposite directions. Each "rung" of the ladder is made up of two nitrogen bases, paired together by hydrogen bonds. Because of the highly specific nature of this type of chemical pairing, base A always pairs with base T, and likewise C with G. So, if you know the sequence of the bases on one strand of a DNA double helix, it is a simple matter to figure out the sequence of bases on the other strand.

DNA's unique structure enables the molecule to copy itself during cell division. When a cell prepares to divide, the DNA helix splits down the middle and becomes two single strands. These single strands serve as templates for building two new, double-stranded DNA molecules - each a replica of the original DNA molecule. In this process, an A base is added wherever there is a T, a C where there is a G, and so on until all of the bases once again have partners.

In addition, when proteins are being made, the double helix unwinds to allow a single strand of DNA to serve as a template. This template strand is then transcribed into mRNA, which is a molecule that conveys vital instructions to the cell's protein-making machinery.

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Last Updated: June 16, 2015

Originally posted here:
Deoxyribonucleic Acid (DNA) Fact Sheet - Genome.gov

indigomoth Post 37 @Mor - It's important to note that, while Watson and Crick did put the final finishing touches on what scientists believed to be the shape of DNA, they had a lot of help and were only the very last in a chain of discoveries.

They came into the game knowing that DNA was probably composed of two strands and what elements made up those strands and that the gene markers made up the DNA, they weren't the DNA itself.

In particular Rosalind Franklin did a lot of work on the DNA structure and discovered that it was made up of two strands before the other two basically used all her work to prove their own theory. She hardly ever gets credit, since they won the Nobel prize, but I think that's a shame because our understanding of DNA sequencing owes a lot more to her than to them.

They were right on the verge of a breakthrough when one of them had a dream about a pair of snakes, coiled against each other, one with a head pointed down, the other with the head pointed up.

The next day, he realized that if DNA models were arranged like that, it would fit everything and history was made.

easier to understand! Thanks!

thank you! its easy to understand and to cite.

Thanks lot. It will help me for my research on dna.

thanks. this article is understandable and helpful at the same time. keep up the good work people.

Wow. Thank you! I learned a lot. Also you saved me because i have to do a project on dna and it's due tomorrow and i didn't even get started yet. yikes!

Thanks. this makes it easier to understand.

this was really helpful. you saved my butt.

thanks. this makes it easier to understand.

really easy to understand. thanks!

this seems like a nice article.

Short, simple, to the point! Thanks, this helped me out a lot on my Biology final.

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What is DNA? (with pictures)

Laboratory experiments, computer explorations, and an interactive exhibition for students, educators, and the public.

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The DNALC has teamed up with the Breakthrough Prize and Khan Academy to design a cutting-edge $100,000 Science Lab as part of the $400,000 grand prize for this new competition. Move fast! The deadline is October 7, 2015.

Join the world-renowned Cold Spring Harbor Laboratory as a Faculty Teaching Fellow at DNA Learning Center Asia China's first hands-on genetics education center.

Gene Screen was named the National Human Genome Research Institute's and Smithsonian Institution's August 2015 "Resource of the Month" on Unlocking Life's Code!

The DNALC family of websites includes 2- and 3-D animations, scientist interviews (including 12 Nobel laureates!), historical images, and teaching aids.

Roll over a screenshot for info. Click to launch site.

The Eugenics Archive includes 2,400 photographs, pedigrees, letters, brochures, manuscripts, and articles from archives in the US and UK. Essays by science historians put the vast image database into context.

Discover the concepts and experiments that define the fields of genetics and molecular biology. This animated primer features the work of over 100 scientists and researchers. Includes animations, scientist video interviews, biographies, photo galleries, and links.

Animations present the cause, inheritance, and treatment of 15 common genetic disorders. Interviews with doctors, researchers, healthcare providers, and individuals affected by a disorder offer personal perspectives. Partner site to DNA from the Beginning.

DNAi looks back on the discovery of the DNA structure with a vast collection of interviews and interactive 2- and 3-D animations. myDNAi provides teacher-oriented resources including guides, activities, lesson plans, and the online Lesson Builder.

Explore cancer biology, cancer pathways, and the molecular basis of diagnosis & treatment. Use Teacher Center to inform students on how molecular and cellular genetics are integrated into cancer prevention, diagnosis, and treatment.

The maize genome sequence is just the most recent of experiments with corn stretching back 10,000 years. Weed to Wonder tells the story how human ingenuity transformed a common Mexican weed (Teosinte) into a modern food and fuel wonder (corn).

Learn About SMA, developed with support from the Spinal Muscular Atrophy Foundation, is a resource for SMA patients, families and researchers, including stories of living with SMA and the science behind emerging therapies.

G2C Online is modeled on principles of neural networking, which examines current research to discover the molecular and cellular basis of human thinking. Use network maps to explore our library of 750+ items, including an interactive 3-D brain.

These sites are built around laboratory and bioinformatics experiments and were often developed in collaboration with Cold Spring Harbor Laboratory scientists.

Roll over a screenshot for info. Click to launch site.

Analyze your DNA with the DNALC's bioinformatics tools: Sequence Server, Allele Server, and Simulation Server. Compare your DNA with DNA from other humans and other species stored in a database maintained by the DNALC.

Kits developed in collaboration with Carolina Biological Supply Company provide lab protocols online and for download and accompanying resources.

Learn about plant genomes by using bioinfomatics to analyze newly sequenced genes in rice and maize. Animated tutorials lead into step-by-step analysis of a gene model using Apollo, research software for gene annotation.

Gene Boy is a simple, multi-function, sequence analysis tool. Enter your own sequence or use a preloaded sequence to perform several analyses and tranformations on the sequence.

Find out what DNA tells us about human origins. Use your own DNA to explore relationships between different ethnic populations. Complete with laboratory protocols and information on how to send samples to the DNALC for sequencing.

Bring students up-to-date on advances in plant genetics and genomics by integrating laboratory experiences with online bioinformatics resources.

Use this lab notebook with experiment- and bioinformatics curriculum on RNAi in C. elegans. Has laboratory protocols, photos and videos of C. elegans mutants, and a check-out system for C. elegans mutants and E. coli feeding strains.

The Urban Barcode Project (UBP) is a science competition spanning the five boroughs of New York City made possible by funding from the Alfred P. Sloan Foundation. In the project, student research teams use DNA barcoding to explore biodiversity in NYC.

Lab Center provides pre- and post-visit activities for laboratory field trips. Video intros, online and downloadable protocols, animations, and videos enhance student understanding. Password-protected teacher resources also included.

DNA Barcoding 101 includes experimental method and supporting resources for using DNA barcoding to identify plants or animals - or products made from them.

DNA Subway is a bioinformatics workspace that makes high-level genome analysis available to biology students and educators. Predict and annotate genes in up to 100,000 basepairs of DNA and prospect entire plant genomes.

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DNA Learning Center

Monty Rakusen/Photodisc/Getty Images

Popularized by its use in high-profile criminal investigations and paternity cases, DNA, deoxyribonucleic acid, is most commonly used to prove a relationship to an individual. New tests created in recent years, however, have also turned DNA into a popular tool for determining ancestry and predicting health and genetic traits. As DNA is passed down from one generation to the next, some parts remain almost unchanged, while other parts change greatly.

This creates an unbreakable link between generations and it can be of great help in reconstructing our family histories.

While it can't provide you with your entire family tree or tell you who your ancestors are, DNA testing can:

DNA tests have been around for many years, but it is only recently that the cost of genetic testing has finally come down into the realm of possibility for the average individual interested in tracing their roots. Some homeDNA test kits can often be ordered for less than $100 (cost varies by test)andusually consist of a cheek swab or a spit collection tube to easily collect a sample of cells from the inside of your mouth. You send back the sample through the mail and within a month or two you receive the results - a series of numbers that represent key chemical "markers" within your DNA.

These numbers can then be compared to results from other individuals to help you determine your ancestry.

Confused with all the talk of markers, mutations and haplotypes? See Genetic Basics: Understanding the Clues Found in Our DNA

There are threebasic types of DNA tests available for genealogical testing. Each has a different purpose and one can only be used by males.

Autosomal DNA (atDNA)(All lines, available for both men and women) - Available for both men and women, this test surveys 700,000+ markers on all 23 chromosomes to look for connections along all of your family lines (maternal and paternal). The test results provide some information about your ethnic mix (thepercentage of your ancestry that comes from Central Europe, Africa, Asia, etc.), as well as as helps to identify cousins (1st, 2nd, 3rd, etc.) on any of your ancestral lines. Autosomal DNA only survives recombination (the passing down of DNA from your various ancestors) for an average of 57 generations, so this test is most useful for connecting with genetic cousins and connecting back to more recent generations of your family tree.

mtDNA Tests(direct maternal line, available forboth men and women)- Mitochondrial DNA (mtDNA) is contained in the cytoplasm of the cell, rather than the nucleus. This type of DNA is passed by a mother to both male and female offspring without any mixing, so your mtDNA is the same as your mother's mtDNA, which is the same as her mother's mtDNA. mtDNA changes very slowly, so iftwo people have an exact match in their mtDNA, then there is a very good chance they share a common maternal ancestor, but it is hard to determine if this is a recent ancestor or one who lived hundreds of years ago. It is important to keep in mind with this test that a male's mtDNA comes only from his mother and is not passed on to his offspring.

Example: The DNA tests that identified the bodies of the Romanovs, the Russian imperial family, utilized mtDNA from a sample provided by Prince Philip, who shares the same maternal line from Queen Victoria.

Y-DNA Tests(direct paternal line, available for males only)- The Y chromosome in the nuclear DNA can also be used to establish family ties. The Y chromosomal DNA test (usually referred to as Y DNA or Y-Line DNA) is only available for males, since the Y chromosome is only passed down the male line from father to son. Womendon't have a Y chromosome!Tiny chemical markers on the Y chromosome create a distinctive pattern, known as a haplotype, that distinguishes one male lineage from another. Shared markers can indicate relatedness between two men, though not the exact degree of the relationship. Y chromosome testing is most often used by individuals with the same last name to learn if they share a common ancestor.

Example: The DNA tests supporting the probability that Thomas Jefferson fathered the last child of Sally Hemmings were based on Y-chromosome DNA samples from male descendants of Thomas Jefferson's paternal uncle, since there were no surviving male descendants from Jefferson's marriage.

Markers on both mtDNA and Y chromosome tests can also be used to determine an individual's haplogroup, a grouping of individuals with the same genetic characteristics. This test may provide you with interesting information about the deep ancestral lineage of your paternal and/or maternal lines.

Next > What Can I Expect to Learn From the Tests?

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Ancestry DNA Tests for Genealogists - Information

Deoxyribonucleic acid (DNA) in a living cell contains the master blueprint for the production of proteins and for the replication of itself. It is the repository for the hereditary information. DNA accomplishes protein production by first providing a pattern for the production of mRNA, a process called transcription. The RNA then contains the information from the DNA to manufacture a protein, a process called translation. Some proteins are structural, but some are control proteins called enzymes. These enzymes are employed in the production of proteins, even copies of themselves, so enzymes are used to make other enzymes. Each protein, including enzymes, is made according to a pattern of nucleotides along a segment of the DNA called a "gene". A single living cell contains thousands of enzymes.

Another way to organized these ideas is in terms of the "central dogma" of molecular biology.

Though a useful organizing structure, the "central dogma" has numerous exceptions. For example, retroviruses use "reverse transcription" to construct DNA from RNA. In general, not every gene gets expressed all the way to the construction of proteins. Some RNAs have other tasks to do, such as the ribosomal RNA and other specifically tasked RNAs with specific tasks in the cell.

Biochemical concepts

Chemistry concepts

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DNA - Georgia State University

Remains of unidentified soldiers who died aboard battleship Oklahoma during 1941 Pearl Harbor attack are being reexamined and subjected to DNA testing in order to confirm their identities; severe damage done to bodies on Oklahoma, one of two ships in battle damaged beyond repair, has made identification process difficult. MORE

Hannah Landenmark study in journal PLoS Biology calculates global biodiversity using new metric of amount of DNA found on Earth; study reports Earth contains around 50 trillion trillion trillion DNA base pairs. MORE

David Rosenberg, who was given up for adoption by his mother Margaret Erle Katz in 1962, relocated her with help of a DNA testing kit and the Internet, only to have less than a month with her before he succumbed to thyroid cancer; growing number of adoptees are locating birth parents using similar tools. MORE

Atlanta jury awards more than $2 million to Atlas Logistics Group Retail Services workers who were required to submit to DNA samples in effort to identify out who had been defecating in warehouse. MORE

DNA matching Richard W Matt and David Sweat, murderers who escaped from Clinton Correctional Facility in upstate New York, is found in cabin 15 miles from prison; Matt and Sweat were discovered missing from prison on June 6. MORE

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Researchers have created fuller picture of how Ebola virus spread and evolved during 2014 outbreak by sequencing genomes of viruses from over 400 patients in Sierra Leone, Guinea and Liberia. MORE

Study published in journal Nature finds that Kennewick Man, 8,500-year-old skeleton that was discovered in Washington state riverbed, has no European DNA, and that he was likely most closely related to Native Americans; remains became subject of controversy as various groups attempted to claim them. MORE

London-based skincare store GeneU uses DNA testing to match treatments to each customer. MORE

Two studies in journal Nature present largest examinations ever done of ancient European DNA, extracted from 170 skeletons found in countries from Spain to Russia; both studies show Europeans descend from three groups who entered area at different stages in history. MORE

Atlanta judge rules that Atlanta warehouse owner Atlas Logistics Group Retail Services violated Genetic Information Nondiscrimination Act when it tested DNA of two men to determine if they had been leaving piles of feces around workplace; decision in unusual case shows scope of law goes beyond its original intent. MORE

Mat Johnson Lives essay describes taking DNA test in order to clear up question of how black he really is, and having one done for his mother as well; notes that there are issues of identity that cannot be resolved by finding out details of one's racial heritage. MORE

Researchers are making progress in using immunotherapy to fight cancer, or using DNA mutations inherent in immune system to beat cancer at its own game; questions remain, however, as to why treatments work better against some cancers than others and why some patients do not respond. MORE

National Institute of Standards and Technology announces new reference standards that could be used to ensure accuracy of DNA testing; marks important step towards new era in the use of genetic medicine. MORE

Profile of Dr Jennifer A Doudna, biochemist at University of California, Berkeley, who is fighting for control of potentially highly profitable intellectual property rights to what is known as the Crispr-Cas9 genome editing technique; Doudna, who helped discover the process, is also actively working to deepen scientific community's understanding of bioethics concerns that have arisen from the revelation of this new way to alter DNA. MORE

Dr Love Dalen study published online in Current Biology reports that researchers have sequenced DNA of woolly mammoth and have determined that species most likely died out on an isolated island from inbreeding. MORE

Law enforcement authorities arrest Joseph Giardala at Los Angeles International Airport and return him to New York to face charges after DNA evidence links him to 1995 rape case in West Village; case is latest effort by Manhattan District Attorney Cyrus Vance Jr to use DNA to solve cold cases. MORE

Chinese researchers try and fail to permanently alter DNA in human embryos; widely-predicted failure follows outcry from scientific community, which had called for halt to research until it could be proved safe and until ethical debate could proceed; researchers were attempting to alter DNA in manner that would be passed on to future generations. MORE

DNA-matching web sites have brought to forefront stories of babies illegally sold by Gertrude Pitkanen of Butte, Mont, to adoptive couples through the 1950s; baby-sellers like Pitkanen, midwife who also performed illegal and sometimes fatal abortions, are part of mid-20th century American subculture; so-called Gertie's Babies, who have found relatives through sites, say they are unique as they never found living biological parents due to how securely secrets were kept. MORE

DNA study published in online digital library bioRxiv reports that geneticists in Great Britain have found Armenians are mix of ancient populations that existed from 3000 to 2000 BC; period confirms date given by fifth century historian Movses Khorenatsi for founding of Armenia. MORE

Scientific community is engaged in debate about whether majority of any given genome's DNA actually serves purpose; recent research has caused some to question idea, and debate is in many ways latest skirmish in intellectual battle that has been going on for 200 years. MORE

Study in journal Science concludes that wheat has existed in Great Britain for 8,000 years, according to DNA evidence, suggesting that it made its way from Neolithic farmers of Southern Europe to Mesolithic hunter-gatherers of Britain. MORE

Scientists are developing tools that allow investigators to create facial image of suspect using DNA found at crime scene; process, known as forensic DNA phenotyping, has raised concerns among some who question technology's accuracy or warn that it could increase racial profiling or lead to privacy violations. MORE

Study in journal Current Biology shows that mice embryos injected with bits of human DNA grow brains 12 percent larger than embryos injected with chimpanzee genes, demonstrating role that gene sequence HARE5 plays in human brain development. MORE

Scientists are finding that they can confirm presence of animal species in a particular location and track their movements by collecting animal's DNA that was shed in environment; DNA samples may persist in area for weeks, allowing researchers to detect invasive and resurgent species, animal diversity, and, perhaps eventually, to measure animal populations. MORE

Pres Obama plans to request hundreds of millions of dollars to fund research into medical treatments attuned to specific patients' DNA and other characteristics; some experts consider so-called 'personalized medicine' or 'individualized medicine' to be forefront of field. MORE

California's First District Court of Appeal strikes down state law requiring collection of DNA from anyone arrested on suspicion of committing a felony, citing state Constitution's ban on unreasonable search and seizure. MORE

Nobel laureate James D Watson, a pioneer in DNA science, will auction his prize medal and donate much of proceeds to educational institutions; move is part of Watson's effort to redeem himself after making offensive remarks about race in 2007 that tarnished his reputation. MORE

DNA analysis of bite marks on harbor porpoises shows that gray seals are often responsible for wounds. MORE

Research shows that obtaining DNA swab from fang mark of snake bite can accurately identify type of snake, helping medical professionals to administer correct antivenin. MORE

Office of Chief Medical Examiner holds New York City Missing Persons Day to help identify the roughly 1,200 bodies they have received since about 1990 that they have been unable to identify; relatives gather to offer DNA samples, which will be used to create a corresponding forensic number that is then crosschecked against genetic information in a city database and others maintained by municipalities across the country. MORE

Study in journal Nature reports that scientists have reconstructed genome of man who lived 45,000 years ago, by far the oldest genetic record ever obtained from modern humans; research provides new clues to expansion of modern humans from Africa into Europe and Asia, as well as strong evidence that early humans interbred with Neanderthals. MORE

Experts working to identify the victims of Malaysia Airlines Flight 17 say they have positively identified 173 individuals from DNA samples. MORE

Food and Drug Administration approves first screening test for colon cancer that uses patients DNA to help spot potentially deadly tumors and growths. MORE

Italian police link Massimo Giuseppe Bossetti to 2011 murder of 13-year-old Yara Gambirasio after embarking on country's largest DNA dragnet, taking genetic samples from nearly 22,000 people; DNA testing also unexpectedly revealed that Bossetti was the illegitimate son of a man who had died in 1999, setting off debate over risks of privacy violations in criminal investigations involving DNA searches. MORE

Dr Bryan Sykes study in Proceedings of the Royal Society B performs first rigorous genetic analysis of three dozen hair samples that collectors claim came from undiscovered living humanoids, such as the Yeti or Sasquatch; study reveals that hairs came from range of known creatures, from humans to dogs. MORE

New fertility treatment could avoid certain hereditary diseases by altering genetic makeup of egg, raising issues of whether or not such a process is ethical or even safe. MORE

Study published in journal Nature Communications reports that researchers are able to determine where strain of malaria originated by using DNA 'bar code' of 23 short snips from genes of parasites. MORE

Researchers at University of California, San Francisco, use DNA sequencing to pinpoint, within 48 hours, what had been causing 14-year-old Joshua Osborn's brain to swell for weeks; breakthrough holds great promise for diagnostics, but experts say it will be years before method is in widespread use; case is reported in the New England Journal of Medicine. MORE

Adam Liptak Sidebar column; South Carolina Supreme Court will decide whether to hear appeal of Billy Wayne Cope, who claims his confessions in 2001 rape and murder of his daughter were coerced; DNA tests identified a different man, James Sanders, as the perpetrator. MORE

Scientists at Scripps Research Institute create first living organism with artificial DNA, taking significant step toward altering the fundamental alphabet of life; accomplishment could lead to new antibiotics, vaccines and other products, though a lot more work needs to be done before this is practical; research, published online in journal Nature, is bound to raise safety concerns and questions about whether humans are playing God. MORE

Study in journal PLoS One reports that Harvard researchers generated hemihelix, helix that changes direction midway, while working with complex rubber band; unusual shape is variation on helix often associated with DNA strand. MORE

Op-Ed article by evolutionary geneticist Svante Paabo warns against using sequenced genomes of Neanderthals to re-create Neanderthal individuals; contends from an ethical perspective such an idea should be condemned, and argues that using stem cells to create cells and tissues in test tubes for research is far more ethically defensible and technically feasible. MORE

Scientists have revealed that unusual repeating DNA sequence occurring next to gene in common bacterium are part of sophisticated immune system used to fight viruses; molecular system, known as Crispr, may provide scientists with power to edit genome and make precise changes to DNA of humans, essentially rewriting code of life. MORE

Municipal administration in Naples, Italy, decides to take DNA samples of dog waste on the sidewalks so that they may track down owners who do not pick up after their dogs; cutting-edge campaign is attempt to address widespread urban problem. MORE

British scientists will grind up some of King Richard IIIs bones to try to sequence his genetic code, about a year and a half after discovery of his corpse. MORE

British scientists will grind up some of King Richard IIIs bones to try to sequence his genetic code, about a year and a half after discovery of his corpse. MORE

Anne Eisenberg Novelties column holds that as technology becomes more sophisticated, genomic sequencing will inevitably expand into the world of newborns, but the process has both medical and ethical implications. MORE

Two studies show how the legacy of Neanderthals endures 30,000 years after their extinction, finding Neanderthal genes in skin and hair that may have helped humans evolve; findings appear in journals Nature and Science. MORE

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DNA - News - Science - The New York Times