Nyob hauv kab lus no koj tuaj yeem kawm txog lub luag haujlwm lom neeg ntawm DNA. Yog li, cov ntawv luv no paub txhua tus neeg los ntawm lub rooj zaum hauv tsev kawm ntawv, tab sis tsis yog txhua tus muaj lub tswv yim tias nws yog dab tsi. Tom qab chav kawm biology hauv tsev kawm ntawv, kev paub tsawg tsawg ntawm cov noob caj noob ces thiab noob caj noob ces tseem nyob hauv lub cim xeeb, txij li cov menyuam yaus tau muab cov ncauj lus nyuaj no tsuas yog superficially. Tab sis qhov kev paub no (lub luag haujlwm lom neeg ntawm DNA, cov txiaj ntsig nws muaj rau lub cev) tuaj yeem pab tau zoo kawg.
Cia peb pib nrog qhov tseeb tias nucleic acids ua haujlwm tseem ceeb, uas yog, lawv ua kom lub neej txuas ntxiv mus. Cov macromolecules no tau nthuav tawm hauv ob hom:
DNA (DNA);
Lawv yog cov xa tawm ntawm cov phiaj xwm caj ces rau cov qauv thiab kev ua haujlwm ntawm lub cev hlwb. Wb tham txog lawv ntau yam ntxiv.
DNA and RNA
Cia peb pib nrog cov ceg ntawm kev tshawb fawb cuam tshuam nrog qhov nyuaj li cascov lus nug xws li:
- kawm txog cov ntsiab cai ntawm kev khaws cov ntaub ntawv keeb kwm yav dhau los;
- nws siv;
- kis;
- kawm txog cov qauv ntawm biopolymers;
- their functions.
Txhua yam no yog kawm los ntawm molecular biology. Nws yog nyob rau hauv no ceg ntawm biological sciences cov lus teb rau lo lus nug ntawm dab tsi lub luag hauj lwm lom ntawm DNA thiab RNA yuav nrhiav tau.
Cov macromolecular compounds tsim los ntawm nucleotides hu ua "nucleic acids". Nws nyob ntawm no tias cov ntaub ntawv hais txog lub cev yog khaws cia, uas txiav txim siab txog kev loj hlob ntawm tus kheej, kev loj hlob thiab kev tsim kho.
Qhov kev tshawb pom ntawm deoxyribonucleic thiab ribonucleic acid poob rau xyoo 1868. Tom qab ntawd cov kws tshawb fawb tau tswj xyuas lawv hauv cov nuclei ntawm leukocytes thiab spermatozoa ntawm elk. Cov kev tshawb fawb tom qab tau pom tias DNA tuaj yeem pom hauv txhua lub hlwb ntawm cov nroj tsuag thiab tsiaj txhu. Tus qauv DNA tau nthuav tawm xyoo 1953 thiab Nobel nqi zog rau kev tshawb pom tau muab tsub rau xyoo 1962.
DNA
Cia peb pib ntu no nrog qhov tseeb tias muaj 3 hom macromolecules tag nrho:
- deoxyribonucleic acid;
- ribonucleic acid;
Yproteins.
Tam sim no peb yuav ua tib zoo saib cov qauv, lub luag haujlwm ntawm DNA. Yog li, qhov biopolymer no xa cov ntaub ntawv ntawm kev tsim noob neej, kev loj hlob nta tsis yog ntawm cov cab kuj, tab sis kuj ntawm tag nrho cov tiam dhau los. DNA monomer yog nucleotide. Yog li, DNA yog qhov tseem ceeb ntawm cov chromosomes, muaj cov kab mob caj ces.
Kev kis ntawm qhov no li cascov ntaub ntawv? Tag nrho cov ntsiab lus yog nyob rau hauv lub peev xwm ntawm cov macromolecules los tsim lawv tus kheej. Lawv tus lej tsis muaj qhov kawg, uas tuaj yeem piav qhia los ntawm lawv qhov loj me, thiab yog li ntawd, los ntawm ntau tus lej ntawm ntau yam nucleotide sequences.
DNA qauv
Yuav kom nkag siab txog lub luag haujlwm lom neeg ntawm DNA hauv lub cell, nws yuav tsum tau paub txog cov qauv ntawm cov molecule no.
Cia pib nrog qhov yooj yim tshaj plaws, txhua nucleotides hauv lawv cov qauv muaj peb yam:
- nitrogenous puag;
- pentose qab zib;
- phosphate group.
Txhua tus neeg nucleotide hauv DNA molecule muaj ib lub hauv paus nitrogenous. Nws tuaj yeem yog ib qho ntawm plaub qhov ua tau:
- A (adenine);
- G (guanine);
- T (thymine).
YC (cytosine);
A thiab G yog purines, thiab C, T thiab U (uracil) yog pyramidins.
Muaj ntau txoj cai rau qhov piv ntawm nitrogenous hauv paus, hu ua Chargaff's txoj cai.
- A=T.
- G=C.
- (A + G=T + C) peb tuaj yeem hloov txhua yam tsis paub mus rau sab laug thiab tau txais: (A + G) / (T + C)=1 (cov qauv no yog qhov yooj yim tshaj plaws thaum daws teeb meem hauv biology).
- A + C=G + T.
- Tus nqi ntawm (A + C) / (G + T) yog qhov tsis tu ncua. Hauv tib neeg, nws yog 0.66, tab sis, piv txwv li, hauv cov kab mob, nws yog los ntawm 0.45 txog 2.57.
Cov qauv ntawm txhua DNA molecule zoo li ob npaug ntawm cov helix. Nco ntsoov tias cov chains polynucleotide yog antiparallel. Ntawd yog, qhov chaw ntawm nucleotidecov khub ntawm ib qho strand yog nyob rau hauv thim rov qab tshaj cov nyob rau lwm yam. Txhua qhov tig ntawm lub helix no muaj ntau txog 10 nucleotide khub.
Cov saw hlau no txuas ua ke li cas? Vim li cas lub molecule muaj zog thiab tsis tawg? Nws yog txhua yam hais txog hydrogen daim ntawv cog lus ntawm nitrogenous hauv paus (nruab nrab A thiab T - ob, ntawm G thiab C - peb) thiab kev sib cuam tshuam hydrophobic.
Thaum kawg ntawm ntu, kuv xav hais tias DNA yog cov organic molecule loj tshaj plaws, qhov ntev ntawm qhov txawv ntawm 0.25 txog 200 nm.
Kev sib tw
Cia peb saib kom ze ntawm kev sib cog lus sib txuas. Peb twb tau hais tias khub ntawm nitrogenous bases yog tsim tsis nyob rau hauv ib tug chaotic yam, tab sis nyob rau hauv ib tug nruj sequence. Yog li, adenine tsuas tuaj yeem khi rau thymine, thiab guanine tsuas tuaj yeem khi rau cytosine. Qhov kev sib txuas ua ke ntawm cov khub hauv ib txoj hlua ntawm ib qho molecule dictates lawv txoj kev npaj rau lwm tus.
Thaum rov ua dua lossis ua ob npaug los tsim cov DNA tshiab molecule, txoj cai no, hu ua "complementarity", yuav tsum tau ua. Koj tuaj yeem pom cov qauv hauv qab no, uas tau hais hauv cov ntsiab lus ntawm Chargaff cov cai - tus naj npawb ntawm cov nucleotides hauv qab no yog tib yam: A thiab T, G thiab C.
Replication
Tam sim no cia peb tham txog lub luag haujlwm lom neeg ntawm DNA replication. Cia peb pib nrog qhov tseeb tias cov molecule no muaj lub peev xwm los tsim nws tus kheej. Lo lus no yog hais txog kev sib txuas ntawm tus ntxhais molecule.
Hauv xyoo 1957, peb tus qauv ntawm cov txheej txheem no tau thov:
- conservative (tus thawj molecule yog khaws cia thiab ib tug tshiab yog tsim);
- semi-conservative(tawg thawj molecule rau hauv monochains thiab ntxiv cov hauv paus ntxiv rau lawv txhua tus);
- dispersed (molecular decay, fragment replication thiab random collection).
Cov txheej txheem rov ua dua muaj peb kauj ruam:
- pib (txhim kho ntawm DNA seem siv lub helicase enzyme);
- elongation (lengthening ntawm cov saw los ntawm kev ntxiv nucleotides);
- xaus (mus txog qhov ntev).
Cov txheej txheem nyuaj no muaj lub luag haujlwm tshwj xeeb, uas yog, lub luag haujlwm lom neeg - kom ntseeg tau qhov tseeb ntawm cov ntaub ntawv caj ces.
RNA
Qhia seb lub luag haujlwm lom neeg ntawm DNA yog dab tsi, tam sim no peb xav hloov mus rau kev txiav txim siab ntawm ribonucleic acid (uas yog, RNA).
Cia peb pib nqe lus no los ntawm kev hais tias cov molecule no tseem ceeb npaum li DNA. Peb tuaj yeem kuaj pom nws hauv txhua yam kabmob, prokaryotic thiab eukaryotic hlwb. Cov molecule no txawm pom nyob rau hauv ib co kab mob (peb tab tom tham txog cov kab mob RNA).
Ib qho tshwj xeeb ntawm RNA yog muaj ib txoj hlua ntawm cov molecules, tab sis, zoo li DNA, nws muaj plaub lub hauv paus nitrogenous. Hauv qhov no nws yog:
- adenine (A);
- uracil (U);
- cytosine (C);
- guanine (G).
Txhua RNAs tau muab faib ua peb pawg:
- matrix, uas feem ntau hu ua cov ntaub ntawv (txo yog ua tau ob hom: mRNA lossis mRNA);
- transport (tRNA);
- ribosomal (rRNA).
Functions
Tom tau hais txog lub luag haujlwm lom neeg ntawm DNA, nws cov qauv thiab cov yam ntxwv ntawm RNA, peb xav kom txav mus rau cov haujlwm tshwj xeeb (kev ua haujlwm) ntawm ribonucleic acids.
Cia peb pib nrog mRNA lossis mRNA, lub luag haujlwm tseem ceeb ntawm kev hloov pauv cov ntaub ntawv los ntawm DNA molecule mus rau cytoplasm ntawm nucleus. Tsis tas li ntawd, mRNA yog ib qho qauv rau kev tsim cov protein. Raws li qhov feem pua ntawm cov hom molecules no, nws tsawg heev (kwv yees li 4%).
Thiab feem pua ntawm rRNA hauv cell yog 80. Lawv tsim nyog, vim lawv yog lub hauv paus ntawm ribosomes. Ribosomal RNA koom nrog hauv kev tsim cov protein thiab sib sau ua ke ntawm cov saw hlau polypeptide.
Adapter uas tsim cov amino acids ntawm cov saw - tRNA uas hloov cov amino acids mus rau thaj tsam ntawm cov protein synthesis. Qhov feem pua ntawm cov cell yog kwv yees li 15%.
Lub luag haujlwm lom neeg
Hais lus: Dab tsi yog lub luag haujlwm lom neeg ntawm DNA? Thaum lub sijhawm tshawb pom ntawm cov molecule no, tsis muaj cov ntaub ntawv pom tseeb tuaj yeem muab rau qhov teeb meem no, tab sis txawm tias tam sim no tsis yog txhua yam paub txog qhov tseem ceeb ntawm DNA thiab RNA.
Yog tias peb tham txog qhov tseem ceeb ntawm kev lom neeg, ces lawv lub luag haujlwm yog hloov cov ntaub ntawv keeb kwm ntawm ib tiam mus rau tiam, protein synthesis thiab coding ntawm cov qauv protein.
Ntau tus qhia txog cov qauv hauv qab no: cov molecules no txuas nrog tsis yog tsuas yog cov khoom lom neeg, tab sis kuj nrog lub neej ntawm sab ntsuj plig ntawm cov tsiaj txhu. Yog tias koj ntseeg qhov kev xav ntawm metaphysicians, ces DNA muaj kev paub dhau los ntawm lub neej thiab lub zog los saum ntuj los.
