Ba’amurke da ta samu lambar yabo ta Nobel a fannin ilmin sinadarai Kary Mullis ta mutu a California tana da shekaru 74 a duniya. A cewar matarsa, mutuwa ta faru ne a ranar 7 ga watan Agusta. Dalilin shine zuciya da gazawar numfashi saboda ciwon huhu.
James Watson da kansa, wanda ya gano kwayar halittar DNA, zai gaya mana game da gudummawar da ya bayar ga ilimin kimiyyar halittu da kuma wanda ya sami kyautar Nobel.
Cire daga littafin James Watson, Andrew Berry, Kevin Davis
DNA. Tarihin Juyin Halitta
Babi na 7. Halin halittar mutum. Halin rayuwa
...
Masanin kimiyyar halittu Carey Mullis, wanda ya yi aiki a Cetus ne ya ƙirƙira halayen sarkar polymerase (PCR) a cikin 1983. Gano wannan dauki ya yi matukar ban mamaki. Daga baya Mullis ya tuna: “Wata ranar Juma’a da yamma a watan Afrilu 1983, na sami alfijir. Na kasance a bayan motar, ina tuki a kan wata mai haske, titin dutse mai jujjuyawa a Arewacin California, ƙasar gandun daji na redwood." Yana da ban sha'awa cewa a cikin irin wannan yanayi ne ilham ta same shi. Kuma ba wai arewacin California yana da hanyoyi na musamman waɗanda ke inganta fahimta ba; Kawai abokin nasa ya taba ganin Mullis yana gudu ba tare da gangan ba tare da wata titin mota mai dual kankara kuma hakan bai dame shi ba ko kadan. Wani abokinsa ya gaya wa jaridar New York Times cewa: “Mullis yana da hangen nesa cewa zai mutu ta hanyar fadowa cikin bishiyar jajayen itace. Don haka ba ya tsoron komai yayin tuki, sai dai idan akwai itatuwan jajayen da ke tsiro a kan hanya.” Kasancewar redwoods a kan hanya ya tilasta Mullis ya maida hankali kuma ... a nan shi ne, fahimta. Mullis ya sami lambar yabo ta Nobel a fannin ilmin sinadarai saboda ƙirƙira da ya yi a shekarar 1993 kuma tun daga nan ya zama baƙon a cikin ayyukansa. Misali, shi mai goyon bayan ka’idar sake duba cewa AIDS ba ta da alaka da cutar kanjamau, wanda ya zubar da mutuncin kansa sosai tare da tsoma baki ga likitoci.
PCR amsa ce mai sauƙi. Don aiwatar da shi, muna buƙatar nau'ikan sinadarai guda biyu waɗanda aka haɗa su da juna waɗanda ke dacewa da kishiyar maɓalli daban-daban na guntun DNA da ake buƙata. Maƙasudai gajeru ne na DNA mai madauri guda ɗaya, kowanne kusan nau'i-nau'i na tushe 20 a tsayi. Bambance-bambancen abubuwan farko shine cewa sun dace da sassan DNA waɗanda ke buƙatar haɓakawa, wato, samfurin DNA.
(Ana danna hoton) Kary Mullis, wanda ya kirkiro PCR
Ƙayyadaddun PCR ya dogara ne akan samuwar hadaddun hadaddun abubuwa tsakanin samfuri da masu ƙira, gajerun oligonucleotides na roba. Kowane firamare yana dacewa da ɗaya daga cikin madauri na samfuri mai madauri biyu kuma yana iyakance farkon da ƙarshen yankin da aka haɓaka. A gaskiya ma, sakamakon "matrix" shine dukkanin kwayoyin halitta, kuma burin mu shine ware ɓangarorin sha'awar mu daga gare ta. Don yin wannan, samfurin DNA mai ɗauri biyu yana zafi zuwa 95 ° C na mintuna da yawa don raba sassan DNA. Ana kiran wannan mataki denaturation saboda haɗin gwiwar hydrogen tsakanin igiyoyin DNA guda biyu sun karye. Da zarar igiyoyin sun rabu, ana saukar da zafin jiki don ba da damar firamare su ɗaure zuwa samfuri mai ɗaci ɗaya. DNA polymerase yana fara kwafin DNA ta hanyar ɗaure zuwa madaidaiciyar sarkar nucleotide. Enzyme DNA polymerase yana maimaita madaidaicin samfuri ta amfani da firamare azaman firamare ko misali don kwafi. Sakamakon zagayowar farko, muna samun nau'i-nau'i masu yawa na wani sashe na DNA. Na gaba muna maimaita wannan hanya. Bayan kowane sake zagayowar muna samun wurin da aka yi niyya a cikin adadi biyu. Bayan zagayowar PCR ashirin da biyar (wato, a cikin ƙasa da sa'o'i biyu), muna da yankin DNA na sha'awar mu a cikin adadin sau 225 sama da na asali (wato, mun haɓaka shi kusan sau miliyan 34). A gaskiya ma, a cikin shigarwar mun sami cakuda masu mahimmanci, DNA samfuri, DNA polymerase enzyme da kuma sansanonin kyauta A, C, G da T, adadin takamaiman samfurin amsawa (iyakance ta masu farawa) yana girma sosai, kuma lambar na "dogon" kwafin DNA na layi ne, don haka samfuran amsawa sun mamaye.
Ƙaddamar da sashin DNA da ake so: amsawar sarkar polymerase
A farkon zamanin PCR, babban matsalar shine mai zuwa: bayan kowane zagayowar sanyaya, DNA polymerase dole ne a ƙara shi zuwa gaurayar dauki, tunda an kunna shi a zazzabi na 95 ° C. Saboda haka, ya zama dole a sake ƙara shi kafin kowane ɗayan 25 na hawan keke. Hanyar amsawa ba ta da inganci, yana buƙatar lokaci mai yawa da kuma enzyme polymerase, kuma kayan yana da tsada sosai. An yi sa'a, Mahaifiyar Halittu ta zo wurin ceto. Dabbobi da yawa suna jin daɗi a yanayin zafi sama da 37 ° C. Me yasa adadi 37 ° C ya zama mahimmanci a gare mu? Wannan ya faru ne saboda wannan zafin jiki shine mafi kyau ga E. coli, daga abin da aka samo asali na polymerase enzyme na PCR. A cikin yanayi akwai ƙananan ƙwayoyin cuta waɗanda sunadaran, sama da miliyoyin shekaru na zaɓin yanayi, sun zama mafi tsayayya ga yanayin zafi. An ba da shawarar yin amfani da polymerases na DNA daga kwayoyin thermophilic. Wadannan enzymes sun juya sun zama masu zafi kuma sun sami damar jure yawan zagayowar amsawa. Amfani da su ya ba da damar sauƙaƙe da sarrafa PCR. Ɗaya daga cikin na farko na DNA polymerases mai zafi ya keɓanta daga kwayoyin Thermus aquaticus, wanda ke zaune a cikin maɓuɓɓugan zafi na Yellowstone National Park, kuma ana kiransa Taq polymerase.
PCR da sauri ya zama dokin aiki na Aikin Halittar Dan Adam. Gabaɗaya, tsarin bai bambanta da wanda Mullis ya ƙirƙira ba, an yi shi ta atomatik. Ba mu ƙara dogaro da ɗimbin ɗimbin ɗaliban da suka kammala karatun digiri ba da himma suna zuba ɗigon ruwa a cikin bututun gwajin filastik. A cikin dakunan gwaje-gwaje na zamani da ke gudanar da bincike kan kwayoyin halitta, ana yin wannan aikin akan masu jigilar na'ura. Mutum-mutumi na PCR da ke da hannu a cikin aikin jeri mai girma kamar yadda Human Genome ke aiki ba tare da ɓata lokaci ba tare da ɗimbin yawa na polymerase mai ƙarfi. Wasu masana kimiyya da ke aiki kan Tsarin Halittar Halittar Dan Adam sun fusata saboda yawan kuɗin sarauta marasa ma'ana da aka ƙara akan farashin kayan masarufi da mai ikon mallakar PCR, babban kamfanin harhada magunguna na Turai Hoffmann-LaRoche.
Wata “ƙa’idar tuƙi” ita ce hanyar bin diddigin DNA da kanta. Tushen sinadarai na wannan hanyar ba sabon abu ba ne a wancan lokacin: Interstate Human Genome Project (HGP) ta ɗauki wannan dabarar dabarar da Fred Sanger ya haɓaka a tsakiyar 1970s. Ƙirƙirar ta kasance a cikin ma'auni da matakin sarrafa kansa wanda jeri ya iya cimma.
An samo asali ta atomatik a cikin dakin gwaje-gwaje na Lee Hood a Cibiyar Fasaha ta California. Ya halarci makarantar sakandare a Montana kuma ya buga kwallon kafa na kwaleji a matsayin kwata-kwata; Godiya ga Hood, ƙungiyar ta lashe gasar zakarun jihar fiye da sau ɗaya. Har ila yau, fasahar haɗin gwiwarsa ta zo da amfani a cikin aikinsa na kimiyya. Gidan dakin gwaje-gwajen Hood yana da gungun kwararrun masana kimiyyar sinadarai, masanan halittu, da injiniyoyi, kuma nan da nan dakin gwaje-gwajensa ya zama jagora a cikin sabbin fasahohi.
A haƙiƙa, hanyar jeri ta atomatik Lloyd Smith da Mike Hunkapiller ne suka ƙirƙira. Mike Hunkapiller, sannan yana aiki a dakin gwaje-gwaje na Hood, ya tunkari Lloyd Smith tare da ba da shawara don ingantaccen tsarin tsari wanda kowane nau'in tushe zai kasance mai launi daban-daban. Irin wannan ra'ayin na iya ninka ingancin aikin Sanger sau huɗu. A cikin Sanger, lokacin da aka tsara a cikin kowane nau'i na hudu (bisa ga yawan adadin tushe), tare da sa hannu na DNA polymerase, an kafa wani tsari na musamman na oligonucleotides na tsayi daban-daban, ciki har da jeri na farko. Bayan haka, an ƙara foramide a cikin bututu don rabuwar sarkar kuma an yi polyacrylamide gel electrophoresis akan hanyoyi huɗu. A cikin sigar Smith da Hunkapiller, dideoxynucleotides ana yiwa lakabi da rini huɗu daban-daban kuma ana yin PCR a cikin bututu ɗaya. Sa'an nan, a lokacin polyacrylamide gel electrophoresis, Laser katako a wani takamaiman wuri a kan gel yana motsa ayyukan rini, kuma mai ganowa ya ƙayyade abin da nucleotide ke tafiya a halin yanzu ta hanyar gel. Da farko, Smith ya kasance mai raɗaɗi - yana tsoron cewa yin amfani da ƙananan allurai na rini zai haifar da yankunan nucleotide ba za su iya bambanta ba. Duk da haka, samun kyakkyawar fahimta game da fasahar laser, ba da daɗewa ba ya sami hanyar fita daga halin da ake ciki ta hanyar amfani da rini na fluorochrome na musamman waɗanda ke haskakawa lokacin da aka fallasa su zuwa hasken laser.
(Cikakken sigar - 4,08 MB) Buga mai kyau: jerin DNA da aka jera ta amfani da na'ura ta atomatik, wanda aka samo daga na'ura mai sarrafa kanta. Kowane launi yayi daidai da ɗaya daga cikin tushe huɗu
A cikin sigar al'ada ta hanyar Sanger, ɗayan sassan DNA ɗin da aka bincika yana aiki azaman samfuri don haɗa nau'in haɗin gwiwa ta hanyar enzyme DNA polymerase, sannan ana jera jerin gutsuttsuran DNA a cikin gel da girma. Kowane guntu, wanda aka haɗa a cikin DNA yayin haɗawa kuma yana ba da damar gani na gaba na samfuran amsawa, an lakafta shi tare da rini mai kyalli wanda ya dace da tushe mai tushe (an tattauna wannan akan shafi na 124); don haka, haske na wannan guntu zai zama abin gano tushen tushe. Sa'an nan duk abin da ya rage shi ne aiwatar da ganowa da hangen nesa samfuran amsawa. Ana nazarin sakamakon ta kwamfuta kuma an gabatar da shi azaman jerin kololuwa masu launuka iri-iri daidai da nucleotides guda huɗu. Daga nan sai a tura bayanan kai tsaye zuwa tsarin bayanan kwamfuta, tare da kawar da tsarin shigar da bayanai mai cin lokaci da kuma raɗaɗi a wasu lokuta wanda ya sa jerin abubuwan ke da wahala.
» Ana iya samun ƙarin bayani game da littafin a
»
»
Don Khabrozhiteley 25% rangwame ta amfani da coupon - PCR
source: www.habr.com