Hnub no, tsis tshua muaj leej twg yuav xav tsis thoob los ntawm cov ntsiab lus xws li caj ces, genome, DNA, nucleotides. Txhua tus paub txog ob lub helix ntawm DNA thiab tias nws yog nws lub luag haujlwm rau kev tsim tag nrho cov cim ntawm lub cev. Tab sis tsis yog txhua tus paub txog cov hauv paus ntsiab lus ntawm nws cov qauv thiab subordination rau cov kev cai yooj yim ntawm Chargaff.
Yam kev phem kev qias
Tsis muaj ntau qhov kev tshawb pom tau muab lub npe ntawm qhov zoo tshaj plaws nyob rau xyoo pua nees nkaum. Tab sis qhov discoveries ntawm Erwin Chargaff (1905-2002), ib haiv neeg ntawm Bukovina (Chernivtsi, Ukraine), yog undoubtedly ib tug ntawm lawv. Txawm hais tias nws tsis tau txais Nobel nqi zog, nws ntseeg txog qhov kawg ntawm nws lub hnub nyoog uas James Watson thiab Francis Crick nyiag nws lub tswv yim ntawm ob txoj hlua khi ntawm DNA thiab nws qhov khoom plig Nobel.
Universities hauv Poland, Lub Tebchaws Yelemees, Tebchaws USA thiab Fabkis zoo siab uas muaj cov kws tshaj lij biochemist qhia nyob rau ntawd. Ntxiv rau Chargaff cov cai tseem ceeb rau DNA, nws paub txog lwm tus - txoj cai golden. Qhov ntawd yog qhov uas biologists hu nws. Thiab txoj cai golden ntawm E. Chargaff suab zoo li no: "Ib qho ntawm feem ntau insidious thiab nefarious khoom ntawm cov qauv kev tshawb fawbyog lawv nyiam coj mus, thiab qee zaum hloov, kev muaj tiag ". Hauv cov ntsiab lus yooj yim, qhov no txhais tau tias - tsis txhob qhia qhov yuav ua li cas, thiab nws yuav tsis qhia koj qhov twg koj yuav tsum mus nrog tag nrho koj cov lus thov. Rau ntau tus kws tshawb fawb hluas, txoj cai no ntawm Erwin Chargaff tau dhau los ua hom lus ntawm kev tshawb fawb txog kev tshawb fawb.
Kev kawm txuj ci
Nco ntsoov cov ntsiab lus tseem ceeb uas tsim nyog rau kev nkag siab cov ntawv hauv qab no.
Genome - tag nrho ntawm tag nrho cov khoom tsim los ntawm cov kab mob uas tau muab.
Monomers tsim cov polymers - cov qauv chav tsev uas ua ke los tsim cov organic molecules siab.
Nucleotides - adenine, guanine, thymine thiab cytosine - monomers ntawm DNA molecule, organic molecules tsim los ntawm phosphoric acid, carbohydrate nrog 5 carbon atoms (deoxyribose los yog ribose) thiab purine (adenine thiab guanine) cyto pyrimidine thiab thymine) hauv av.
DNA - deoxyribonucleic acid, lub hauv paus ntawm kev sib txuas ntawm cov kab mob, yog ob lub helix tsim los ntawm nucleotides nrog cov khoom noj carbohydrate - deoxyribose. RNA - ribonucleic acid, txawv ntawm DNA nyob rau hauv lub xub ntiag ntawm ribose carbohydrate nyob rau hauv lub nucleotides thiab hloov thymine nrog uracil.
Nws pib ua li cas
Ib pawg kws tshawb fawb ntawm Columbia University hauv New York, coj los ntawm E. Chargaff hauv 1950-1952, tau koom nrog DNA chromatography. Nws twb paub lawm tias nws muaj plaub nucleotides, tab sis tseem tsis tau muaj leej twg paub txog nws cov qauv helical.paub. Ntau qhov kev tshawb fawb tau pom. Tias nyob rau hauv DNA molecule tus naj npawb ntawm purine bases yog sib npaug rau cov pyrimidine bases. Ntau precisely, tus nqi ntawm thymine yeej ib txwm sib npaug rau tus nqi ntawm adenine, thiab tus nqi ntawm guanine sib raug rau tus nqi ntawm cytosine. Qhov kev sib npaug ntawm nitrogenous bases yog Chargaff txoj cai rau deoxyribonucleic thiab ribonucleic acids.
Lub ntsiab lus hauv biology
Nws yog txoj cai no uas tau los ua lub hauv paus uas Watson thiab Crick tau coj thaum muab cov qauv ntawm DNA molecule. Lawv ob-stranded helically twisted qauv ntawm cov pob, xov hlau, thiab cov duab piav qhia qhov sib npaug. Hauv lwm lo lus, Chargaff txoj cai yog tias thymine ua ke nrog adenine thiab guanine ua ke nrog cytosine. Nws yog qhov piv txwv ntawm nucleotides uas haum rau hauv tus qauv spatial ntawm DNA tau thov los ntawm Watson thiab Crick. Qhov kev tshawb pom ntawm cov qauv ntawm deoxyribonucleic acid molecule ua rau kev tshawb fawb kom pom cov qib dav dua: cov hauv paus ntsiab lus ntawm kev hloov pauv thiab kev hloov pauv, kev sib txuas ntawm DNA, kev piav qhia ntawm evolution thiab nws cov txheej txheem ntawm qib molecular..
Chargaff cov cai hauv lawv daim ntawv purest
Kev tshawb fawb niaj hnub tsim cov kev cai tseem ceeb no nrog peb cov lus hauv qab no:
- Tus nqi ntawm adenine sib raug rau tus nqi ntawm thymine, thiab cytosine rau guanine: A=T thiab G=C.
- Tus nqi ntawm purines ib txwm sib npaug rau cov pyrimidines: A + G=T + C.
- Tus naj npawb ntawm nucleotides uas muaj pyrimidine nyob rau hauv txoj hauj lwm 4 thiab 6purine bases, yog sib npaug rau cov nucleotides uas muaj oxo pawg hauv tib txoj haujlwm: A + G \u003d C + T.
Nyob rau xyoo 1990, nrog rau kev tshawb pom ntawm cov thev naus laus zis sib luag (kev txiav txim siab ntawm nucleotides hauv ntu ntev), Chargaff's DNA cov cai tau lees paub.
Cov me nyuam mob taub hau
Hauv tsev kawm theem siab thiab hauv tsev kawm qib siab, kev kawm txog molecular biology yuav tsum muaj kev daws teeb meem ntawm txoj cai Chargaff. Lawv tsuas yog hu cov haujlwm no yog kev tsim kho ntawm DNA thib ob raws li lub hauv paus ntsiab lus ntawm kev ua kom tiav (spatial complementarity ntawm purine thiab pyrimidine nucleotides). Piv txwv li, qhov xwm txheej muab qhov sib lawv liag ntawm nucleotides hauv ib txoj saw - AAGCTAT. Tus menyuam kawm ntawv lossis tus menyuam kawm ntawv yuav tsum rov tsim kho dua tshiab raws li DNA matrix strand thiab thawj Chargaff txoj cai. Cov lus teb yuav yog: GGACGTS.
Lwm hom haujlwm qhia tau hais tias suav qhov hnyav ntawm DNA molecule, paub qhov sib lawv liag ntawm nucleotides nyob rau hauv ib txoj saw thiab lub ntiajteb txawj nqus ntawm nucleotides. Chargaff thawj txoj cai ntawm biology yog suav tias yog qhov tseem ceeb rau kev nkag siab txog cov hauv paus ntawm molecular biochemistry thiab noob caj noob ces.
Rau kev tshawb fawb, tsis yog txhua yam yooj yim heev
E. Chargaff txuas ntxiv mus kawm txog qhov muaj pes tsawg leeg ntawm DNA, thiab 16 xyoo tom qab tshawb pom thawj txoj cai, nws tau faib cov molecule rau hauv ob txoj kab sib cais thiab pom tias tus lej ntawm cov hauv paus tsis sib npaug, tab sis tsuas yog kwv yees li. Qhov no yog Chargaff txoj cai thib ob: nyob rau hauv ib qho caisstrands ntawm deoxyribonucleic acid, tus nqi ntawm adenine yog kwv yees li sib npaug ntawm cov thymine, thiab guanine - rau cytosine.
Kev ua txhaum cai sib luag tau muab faib ncaj qha rau qhov ntev ntawm ntu kev tshuaj xyuas. Qhov tseeb yog khaws cia ntawm qhov ntev ntawm 70-100 txhiab lub hauv paus khub, tab sis ntawm qhov ntev ntawm ntau pua lub hauv paus khub thiab tsawg dua, nws tsis tau khaws cia lawm. Vim li cas hauv qee cov kab mob feem pua ntawm guanine-cytosine siab dua qhov feem pua ntawm adenine-thymine, lossis rov ua dua, kev tshawb fawb tseem tsis tau piav qhia. Tseeb tiag, hauv cov genomes ntawm cov kab mob, kev sib npaug ntawm nucleotides yog qhov tshwj xeeb tshaj li txoj cai.
DNA tsis qhia nws qhov zais cia
Nrog rau kev txhim kho ntawm cov txheej txheem genome sequencing, nws tau pom tias ib qho strand ntawm DNA muaj kwv yees li tib tus naj npawb ntawm cov nucleotides, cov khub hauv paus (dinucleotides), trinucleotides, thiab lwm yam - mus txog oligonucleotides (ntu ntawm 10-20 nucleotides). Cov genomes ntawm tag nrho cov kab mob uas muaj sia nyob ua raws li txoj cai no, tsis muaj kev zam tsawg heev.
Yog li, ob tus kws tshawb fawb Brazilian - biologist Michael Yamagishi thiab mathematician Roberto Herai - tau siv txoj kev xav los tshuaj xyuas cov nucleotide sequence tsim nyog rau lawv los ua txoj cai Chargaff. Lawv muab tau plaub qhov sib npaug thiab sim 32 genomes ntawm hom paub. Thiab nws tau muab tawm tias cov qauv zoo li fractal muaj tseeb rau ntau hom, suav nrog E. coli, nroj tsuag thiab tib neeg. Tab sis tib neeg kev tiv thaiv kab mob thiab kab mob cab uas ua rau wilting saicov txiv ntseej, tsis txhob ua raws li txoj cai ntawm Chargaff txoj cai txhua. Vim li cas? Tseem tsis tau teb.
Biochemists, evolutionary biologists, cytologists thiab geneticists tseem tawm tsam nrog qhov tsis meej ntawm DNA thiab cov txheej txheem ntawm kev qub txeeg qub teg. Txawm hais tias kev ua tiav ntawm kev tshawb fawb niaj hnub no, tib neeg nyob deb ntawm kev nthuav dav lub ntiaj teb. Peb tau kov yeej lub ntiajteb txawj nqus, paub qhov chaw sab nraud, kawm yuav ua li cas hloov cov genomes thiab txiav txim siab cov kab mob ntawm tus menyuam hauv plab thaum ntxov ntawm kev loj hlob ntawm embryo. Tab sis peb tseem nyob deb ntawm kev nkag siab tag nrho cov txheej txheem ntawm cov xwm txheej uas nws tau tsim rau ntau txhiab xyoo hauv ntiaj teb ntiaj teb.
