Ntau tus neeg ib txwm xav paub tias yog vim li cas qee tus yam ntxwv ntawm cov niam txiv tau kis mus rau tus menyuam (piv txwv li, xim qhov muag, plaub hau, ntsej muag, thiab lwm yam). Nws tau raug tshawb fawb pov thawj tias qhov kev hloov pauv no nyob ntawm cov khoom siv caj ces, lossis DNA.
YDNA yog dab tsi?
Tam sim no, deoxyribonucleic acid tau nkag siab tias yog ib qho kev sib txuas ua haujlwm rau kev sib kis ntawm cov yam ntxwv ntawm caj ces. Cov molecule no muaj nyob hauv txhua lub cell ntawm peb lub cev. Cov yam ntxwv tseem ceeb ntawm peb lub cev yog programmed nyob rau hauv nws (ib yam protein yog lub luag hauj lwm rau kev loj hlob ntawm ib tug tshwj xeeb feature).
Nws muaj dab tsi? DNA yog tsim los ntawm complex compounds hu ua nucleotides. Lub nucleotide yog ib qho thaiv lossis cov khoom sib xyaw me me uas muaj nitrogenous puag, phosphoric acid residue thiab qab zib (qhov no, deoxyribose).
DNA yog ob txoj hlua khi uas txhua txoj hlua txuas nrog rau lwm tus los ntawm cov hauv paus nitrogen raws li lub hauv paus ntsiab lus ntawm complementarity.
Tsis tas li ntawd, peb tuaj yeem xav tias DNA muaj cov noob - qee cov nucleotide sequences lub luag haujlwm rau kev tsim cov protein. Dab tsi yog cov yam ntxwv ntawm cov qauv ntawm deoxyribonucleic acid?
Nucleotide
Raws li tau hais, lub hauv paus txheej txheem ntawm deoxyribonucleic acid yog nucleotide. Qhov no yog kev kawm nyuaj. Cov muaj pes tsawg leeg ntawm DNA nucleotide yog raws li nram no.
Ntawm nruab nrab ntawm nucleotide yog tsib lub suab thaj (hauv DNA nws yog deoxyribose, tsis zoo li RNA, uas muaj ribose). Lub hauv paus nitrogenous txuas rau nws, ntawm 5 hom yog qhov txawv: adenine, guanine, thymine, uracil thiab cytosine. Tsis tas li ntawd, txhua nucleotide kuj muaj phosphoric acid residue.
DNA tsuas muaj cov nucleotides uas muaj cov qauv qhia.
Txhua nucleotides tau teeb tsa hauv ib txoj hlua thiab ua raws ib leeg. Pab pawg hauv triplets (peb nucleotides txhua), lawv tsim ib ntu uas txhua triplet sib raug rau ib qho amino acid tshwj xeeb. Qhov tshwm sim yog saw hlau.
Lawv sib xyaw ua ke vim kev sib cog lus ntawm nitrogenous hauv paus. Lub ntsiab kev sib raug zoo ntawm nucleotides ntawm parallel chains yog hydrogen.
Nucleotide sequences yog lub hauv paus ntawm noob. Kev ua txhaum nyob rau hauv lawv cov qauv ua rau ib tug tsis ua hauj lwm nyob rau hauv synthesis ntawm cov proteins thiab manifestation ntawm kev hloov. DNA muaj tib lub noob uas txiav txim siab nyob rau hauv yuav luag txhua tus neeg thiab paub qhov txawv ntawm lwm yam kab mob.
Nucleotide hloov kho
Qee zaum, rau kev hloov pauv ruaj khov ntawm ib qho tshwj xeeb, kev hloov pauv ntawm nitrogenous puag yog siv. Cov tshuaj muaj pes tsawg leeg ntawm DNA yog hloov los ntawm kev sib ntxiv ntawm ib pawg methyl (CH3). Xws li kev hloov kho (ntawm ib qho nucleotide) tso caiTxhim kho cov kev qhia gene thiab hloov cov yam ntxwv rau cov ntxhais.
Xws li "kev txhim kho" ntawm cov qauv ntawm cov molecule tsis muaj kev cuam tshuam rau kev koom tes ntawm nitrogenous bases.
Qhov kev hloov kho no kuj tseem siv rau X-chromosome inactivation. Vim li ntawd, Barr lub cev raug tsim.
Nrog cov carcinogenesis ntau ntxiv, DNA tsom xam pom tias cov saw ntawm nucleotides raug rau methylation ntawm ntau lub hauv paus. Hauv kev soj ntsuam, nws tau sau tseg tias qhov chaw ntawm kev hloov pauv feem ntau yog methylated cytosine. Feem ntau, hauv cov txheej txheem qog, demethylation tuaj yeem pab nres cov txheej txheem, tab sis vim nws txoj kev nyuaj, qhov tshuaj tiv thaiv no tsis ua tiav.
DNA qauv
Muaj ob hom qauv hauv cov qauv ntawm cov molecule. Thawj hom yog linear sequence tsim los ntawm nucleotides. Lawv txoj kev tsim kho yog ua raws li qee txoj cai. Kev sau ntawv ntawm nucleotides ntawm DNA molecule pib ntawm 5' kawg thiab xaus ntawm 3' kawg. Cov saw thib ob, nyob rau sab nraud, yog tsim nyob rau hauv tib txoj kev, tsuas yog nyob rau hauv kev sib raug zoo spatial cov molecules yog ib tug opposite rau lwm tus, thiab 5 '-kawg ntawm ib tug saw yog nyob opposite 3'- kawg ntawm lub thib ob.
Tus qauv thib ob ntawm DNA yog helix. Nws yog tshwm sim los ntawm muaj hydrogen bonds ntawm nucleotides nyob opposite ib leeg. Ib daim ntawv cog lus hydrogen yog tsim los ntawm cov khoom siv nitrogenous sib xyaw ua ke (piv txwv li, tsuas yog thymine tuaj yeem yog qhov sib txawv ntawm adenine ntawm thawj cov saw, thiab cytosine lossis uracil tuaj yeem yog qhov txawv ntawm guanine). Xws li qhov tseeb yog vim qhov tseeb tias kev tsim kho ntawm cov saw thib ob tshwm sim los ntawm thawj zaug, yog li ntawd, muaj kev sib raug zoo ntawm cov hauv paus nitrogenous.
Synthesis of the molecule
DNA molecule ua li cas?
Muaj peb theem nyob rau hauv lub voj voog ntawm nws tsim:
- Txoj kev sib txuas chains.
- Kev sib txuas ntawm cov khoom sib txuas rau ib qho ntawm cov saw hlau.
- Ua tiav ntawm txoj saw thib ob raws li lub hauv paus ntsiab lus ntawm kev sib ntxiv.
Nyob rau theem ntawm kev sib cais ntawm cov molecule, lub luag haujlwm tseem ceeb yog ua los ntawm enzymes - DNA gyrases. Cov enzymes no tau tsom mus rau kev puas tsuaj ntawm hydrogen bonds ntawm chains.
Tom qab kev sib txawv ntawm cov chains, lub ntsiab synthesizing enzyme, DNA polymerase, los ua si. Nws daim ntawv txuas tau pom nyob rau hauv ntu 5'. Tsis tas li ntawd, cov enzyme no txav mus rau ntawm 3'-kawg, ib txhij txuas cov nucleotides tsim nyog rau cov hauv paus nitrogenous. Tau mus txog ib qhov chaw (terminator) ntawm 3'-kawg, cov polymerase raug txiav tawm ntawm cov saw qub.
Tom qab tus ntxhais saw tau tsim, ib daim ntawv cog lus hydrogen tau tsim los ntawm cov hauv paus, uas tuav cov DNA molecule tshiab ua ke.
Kuv tuaj yeem pom qhov molecule no nyob qhov twg?
Yog tias koj delve rau hauv cov qauv ntawm cov hlwb thiab cov ntaub so ntswg, koj tuaj yeem pom tias DNA feem ntau muaj nyob rau hauv lub nucleus ntawm lub cell. Lub nucleus yog lub luag haujlwm rau kev tsim cov tshiab, tus ntxhais, cov hlwb lossis lawv cov clones. Nyob rau tib lub sijhawm, cov ntaub ntawv keeb kwm muaj nyob rau hauv nws tau muab faib nruab nrab ntawm cov hlwb tsim tshiab sib npaug (clones raug tsim) lossis hauv ntu (feem ntau tuaj yeem ua tau.saib zoo li no tshwm sim thaum lub sij hawm meiosis). Kev swb ntawm cov nucleus ua rau muaj kev ua txhaum ntawm kev tsim cov ntaub so ntswg tshiab, uas ua rau kev hloov pauv.
Ntxiv rau, ib hom tshwj xeeb ntawm cov khoom siv los ntawm noob caj noob ces muaj nyob hauv mitochondria. Lawv DNA txawv me ntsis ntawm qhov hauv lub nucleus (mitochondrial deoxyribonucleic acid muaj lub nplhaib puab thiab ua haujlwm sib txawv me ntsis).
Cov molecule nws tus kheej tuaj yeem raug cais tawm ntawm txhua lub hlwb ntawm lub cev (rau kev tshawb fawb, smear los ntawm sab hauv ntawm lub plhu lossis ntshav feem ntau siv). Tsuas yog cov epithelium sloughing thiab qee cov qe ntshav (erythrocytes) tsis muaj genetic khoom.
Functions
Cov khoom xyaw ntawm DNA molecule txiav txim siab qhov ua tau zoo ntawm nws txoj haujlwm ntawm kev xa cov ntaub ntawv los ntawm ib tiam mus rau tiam. Qhov no tshwm sim vim yog kev sib txuas ntawm qee cov proteins uas ua rau pom qhov tshwm sim ntawm ib lossis lwm qhov genotypic (sab hauv) lossis phenotypic (sab nrauv - piv txwv li, qhov muag lossis cov plaub hau xim) zoo.
Kev hloov pauv ntawm cov ntaub ntawv yog ua los ntawm kev siv nws los ntawm cov txheej txheem caj ces. Raws li cov ntaub ntawv encrypted nyob rau hauv genetic code, cov ntaub ntawv tshwj xeeb, ribosomal thiab hloov RNAs yog tsim. Txhua tus ntawm lawv yog lub luag haujlwm rau qhov tshwj xeeb - tus xa xov RNA yog siv los tsim cov proteins, ribosomal RNA koom nrog hauv kev sib dhos ntawm cov protein molecules, thiab thauj RNA tsim cov proteins sib xws.
Txhua yam tsis ua haujlwm hauv lawv txoj haujlwm lossis kev hloov pauv hauv cov qauv ua rau ua txhaum txoj haujlwm thiabcov tsos ntawm atypical traits (mutations).
DNA leej txiv kuaj tso cai rau koj los txiav txim qhov muaj feem cuam tshuam ntawm tib neeg.
kuaj kab mob
Dab tsi tuaj yeem tshawb fawb txog cov khoom siv caj ces siv rau tam sim no?
kev tshuaj ntsuam DNA yog siv los txiav txim siab ntau yam lossis hloov pauv hauv lub cev.
Ua ntej ntawm tag nrho, txoj kev tshawb fawb tso cai rau koj los txiav txim seb muaj kab mob hauv lub cev, muaj kab mob. Cov kab mob no muaj xws li Down syndrome, autism, Marfan syndrome.
Koj tuaj yeem kuaj DNA los txiav txim rau tsev neeg kev sib raug zoo. Kev xeem txiv neej tau ntev tau siv dav hauv ntau yam, feem ntau raug cai, txheej txheem. Txoj kev tshawb no yog sau tseg thaum txiav txim siab txog kev sib raug zoo ntawm cov menyuam yaus tsis raug cai. Feem ntau qhov kev xeem no raug coj los ntawm cov neeg thov kev ua qub txeeg qub teg thaum muaj lus nug los ntawm cov tub ceev xwm.
