Nucleic acids khaws cia thiab xa cov ntaub ntawv caj ces uas peb tau txais los ntawm peb cov poj koob yawm txwv. Yog tias koj muaj menyuam, koj cov ntaub ntawv caj ces hauv lawv cov genome yuav rov ua dua thiab ua ke nrog koj tus khub cov ntaub ntawv caj ces. Koj tus kheej genome yog duplicated txhua zaus txhua lub cell faib. Tsis tas li ntawd, nucleic acids muaj qee ntu hu ua cov noob uas yog lub luag haujlwm rau kev sib txuas ntawm tag nrho cov proteins hauv hlwb. Cov yam ntxwv ntawm cov noob tswj cov yam ntxwv lom ntawm koj lub cev.
cov ntaub ntawv dav dav
Muaj ob chav kawm ntawm nucleic acids: deoxyribonucleic acid (zoo dua hu ua DNA) thiab ribonucleic acid (zoo dua hu ua RNA).
DNA yog ib txoj hlua zoo li cov noob uas tsim nyog rau kev loj hlob, kev loj hlob, lub neej thiab kev tsim tawm ntawm txhua yam kab mob uas muaj sia nyob thiab cov kab mob feem ntau.
Kev hloov pauv hauv DNA ntawm cov kab mob ntau lub cev yuav ua rau muaj kev hloov pauv hauv tiam tom ntej.
DNA yog biogenetic substrate,pom nyob rau hauv txhua yam uas muaj sia nyob, los ntawm cov kab mob uas yooj yim tshaj plaws mus rau cov tsiaj uas muaj kab mob loj heev.
Ntau yam kab mob (virions) muaj RNA hauv cov nucleus ua cov khoom siv caj ces. Txawm li cas los xij, nws yuav tsum tau hais tias cov kab mob nyob ntawm ciam teb ntawm cov tsiaj txhu thiab cov tsiaj tsis muaj sia, vim tias tsis muaj lub xov tooj ntawm tes ntawm tus tswv tsev lawv nyob tsis ua haujlwm.
keeb kwm keeb kwm
Xyoo 1869, Friedrich Miescher cais cov nuclei los ntawm cov qe ntshav dawb thiab pom tias lawv muaj phosphorus nplua nuj tshuaj uas nws hu ua nuclein.
Hermann Fischer nrhiav pom purine thiab pyrimidine hauv paus hauv nucleic acids hauv xyoo 1880.
Nyob rau xyoo 1884, R. Hertwig tau hais tias nucleins yog lub luag haujlwm rau kev sib kis ntawm caj ces.
Hauv xyoo 1899, Richard Altmann tau sau lo lus "core acid".
Thiab tom qab ntawd, hauv 40s ntawm lub xyoo pua 20th, cov kws tshawb fawb Kaspersson thiab Brachet tau pom qhov sib txuas ntawm nucleic acids nrog cov protein synthesis.
Nucleotides
Polynucleotides yog tsim los ntawm ntau nucleotides - monomers txuas ua ke hauv chains.
Hauv cov qauv ntawm nucleic acids, nucleotides raug cais tawm, txhua tus muaj:
- Nitrogen puag.
- Pentose qab zib.
- Phosphate group.
Txhua nucleotide muaj cov nitrogen uas muaj cov ntxhiab tsw qab uas txuas nrog pentose (tsib-carbon) saccharide, uas, dhau los, txuas rau phosphoric acid residue. Xws li monomers, thaum ua ke nrog ib leeg, tsim polymericchains. Lawv txuas nrog covalent hydrogen bonds uas tshwm sim ntawm phosphorus residue ntawm ib lub saw thiab pentose qab zib ntawm lwm cov saw. Cov nyiaj no yog hu ua phosphodiester bonds. Phosphodiester bonds tsim cov phosphate-carbohydrate qaum (skeleton) ntawm DNA thiab RNA.
Deoxyribonucleotide
Cia peb xav txog cov khoom ntawm nucleic acids nyob hauv lub nucleus. DNA tsim cov chromosome apparatus ntawm nucleus ntawm peb cov hlwb. DNA muaj "cov lus qhia software" rau kev ua haujlwm ntawm tes. Thaum lub cell rov tsim nws tus kheej, cov lus qhia no raug xa mus rau lub cell tshiab thaum lub sij hawm mitosis. DNA muaj cov tsos ntawm ob-stranded macromolecule twisted mus rau hauv ib ob helical xov.
Cov nucleic acid muaj phosphate-deoxyribose saccharide skeleton thiab plaub lub hauv paus nitrogenous: adenine (A), guanine (G), cytosine (C) thiab thymine (T). Nyob rau hauv ob-stranded helix, adenine khub nrog thymine (A-T), guanine khub nrog cytosine (G-C).
Xyoo 1953, James D. Watson thiab Francis H. K. Crick tau npaj cov qauv peb-dimensional ntawm DNA raws li cov ntaub ntawv X-ray crystallographic tsawg. Lawv kuj tau xa mus rau biologist Erwin Chargaff qhov kev tshawb pom tias nyob rau hauv DNA, tus nqi ntawm thymine yog sib npaug rau tus nqi ntawm adenine, thiab tus nqi ntawm guanine yog sib npaug rau cov cytosine. Watson thiab Crick, uas tau yeej qhov khoom plig Nobel xyoo 1962 rau lawv txoj kev koom tes rau kev tshawb fawb, tau hais tias ob txoj kab ntawm polynucleotides tsim ob lub helix. Cov threads, txawm tias lawv zoo tib yam, twist nyob rau hauv opposite lus qhia.cov lus qhia. Cov phosphate-carbon chains nyob rau sab nraud ntawm lub helix, thaum lub hauv paus nyob rau sab hauv, qhov chaw lawv khi rau hauv paus ntawm lwm cov saw ntawm covalent bonds.
Ribonucleotides
RNA molecule muaj nyob rau hauv ib leeg-stranded kauv xov. Cov qauv ntawm RNA muaj phosphate-ribose carbohydrate skeleton thiab nitrate bases: adenine, guanine, cytosine thiab uracil (U). Thaum RNA yog tsim los ntawm DNA template thaum lub sij hawm transcription, guanine khub nrog cytosine (G-C) thiab adenine nrog uracil (A-U).
RNA fragments yog siv los tsim cov proteins nyob hauv txhua lub hlwb, uas ua kom lawv txoj kev loj hlob tsis tu ncua thiab faib.
Muaj ob lub luag haujlwm tseem ceeb ntawm nucleic acids. Ua ntej, lawv pab DNA los ntawm kev ua tus neeg nruab nrab uas xa cov ntaub ntawv keeb kwm tsim nyog rau ntau tus ribosomes hauv peb lub cev. Lwm lub luag haujlwm tseem ceeb ntawm RNA yog xa cov amino acid kom raug uas txhua ribosome xav tau los ua cov protein tshiab. Muaj ntau ntau chav sib txawv ntawm RNA.
Kev xa xov RNA (mRNA, lossis mRNA - qauv) yog ib daim qauv ntawm cov txheej txheem DNA ntu uas tau txais los ntawm kev sau ntawv. Neeg xa xov liaison RNA ua ib tug intermediary ntawm DNA thiab ribosomes - cell organelles uas txais cov amino acids los ntawm hloov RNA thiab siv lawv los tsim ib tug polypeptide saw.
Transfer RNA (tRNA) qhib kev nyeem cov ntaub ntawv keeb kwm yav dhau los ntawm tus xa xov RNA, ua rau cov txheej txheem txhais lusribonucleic acid - protein synthesis. Nws kuj tseem thauj cov amino acids txoj cai mus rau qhov chaw protein synthesized.
Ribosomal RNA (rRNA) yog lub tsev tseem ceeb ntawm ribosomes. Nws khi cov qauv ribonucleotide nyob rau hauv ib qho chaw uas nws muaj peev xwm nyeem nws cov ntaub ntawv, yog li pib cov txheej txheem txhais lus.
MiRNAs yog cov RNA me me uas ua raws li kev tswj hwm ntawm ntau cov noob.
Lub luag haujlwm ntawm nucleic acids yog qhov tseem ceeb heev rau lub neej feem ntau thiab rau txhua lub xov tooj ntawm tes. Yuav luag tag nrho cov haujlwm uas lub cell ua tau yog tswj hwm los ntawm cov proteins uas tau tsim los ntawm RNA thiab DNA. Enzymes, cov khoom lag luam protein, catalyze tag nrho cov txheej txheem tseem ceeb: ua pa, plab zom mov, txhua hom metabolism.
Qhov txawv ntawm cov qauv ntawm nucleic acids
| Dezoskiribonucleotide | Ribonucleotide | |
| Function | Kev khaws cia ntev thiab xa cov ntaub ntawv keeb kwm | Kev hloov pauv ntawm cov ntaub ntawv khaws cia hauv DNA rau hauv cov protein; thauj cov amino acids. Khaws cov ntaub ntawv keeb kwm ntawm qee tus kab mob. |
| Monosaccharide | Deoxyribose | Ribose |
| qauv | ob-stranded kauv duab | Ib leeg strand helical zoo |
| Nitrate Bases | T, C, A, G | U, C, G, A |
Cov khoom tshwj xeeb ntawm nucleic acid bases
Adenine thiab guanine byLawv cov khoom yog purines. Qhov no txhais tau hais tias lawv cov qauv molecular suav nrog ob lub fused benzene rings. Cytosine thiab thymine, nyob rau hauv lem, belongs rau pyrimidines, thiab muaj ib lub nplhaib benzene. RNA monomers tsim lawv cov saw siv adenine, guanine thiab cytosine bases, thiab es tsis txhob thymine lawv ntxiv uracil (U). Txhua lub pyrimidine thiab purine hauv paus muaj nws tus kheej cov qauv thiab cov khoom, nws tus kheej cov pawg ua haujlwm txuas nrog lub nplhaib benzene.
Nyob rau hauv molecular biology, tshwj xeeb ib tsab ntawv yog siv los qhia txog nitrogenous bases: A, T, G, C, los yog U.
Pentose qab zib
Ntxiv rau qhov sib txawv ntawm cov nitrogenous hauv paus, DNA thiab RNA monomers txawv hauv lawv cov qab zib pentose. Lub tsib-atom carbohydrate hauv DNA yog deoxyribose, thaum nyob rau hauv RNA nws yog ribose. Lawv yuav luag zoo tib yam hauv cov qauv, tsuas yog ib qho sib txawv: ribose ntxiv ib pawg hydroxyl, thaum nyob rau hauv deoxyribose nws hloov los ntawm hydrogen atom.
Cov Lus Qhia
Nyob rau hauv cov evolution ntawm cov kab mob lom thiab kev txuas ntxiv ntawm lub neej, lub luag hauj lwm ntawm nucleic acids tsis tuaj yeem overestimated. Raws li ib feem tseem ceeb ntawm tag nrho cov nuclei ntawm cov hlwb muaj sia, lawv yog lub luag haujlwm rau kev ua kom tag nrho cov txheej txheem tseem ceeb tshwm sim hauv cov hlwb.
