Nucleic acids ua lub luag haujlwm tseem ceeb hauv lub cell, ua kom nws cov haujlwm tseem ceeb thiab kev tsim tawm. Cov khoom no ua rau nws muaj peev xwm hu lawv qhov thib ob tseem ceeb tshaj plaws lom molecules tom qab cov proteins. Ntau tus kws tshawb fawb txawm muab DNA thiab RNA tso rau hauv thawj qhov chaw, qhia lawv qhov tseem ceeb hauv kev loj hlob ntawm lub neej. Txawm li cas los xij, lawv tau txais qhov chaw thib ob tom qab cov protein, vim tias lub hauv paus ntawm lub neej yog qhov tseeb ntawm polypeptide molecule.
Nucleic acids yog qib sib txawv ntawm lub neej, ntau qhov nyuaj thiab nthuav vim qhov tseeb tias txhua hom molecule ua haujlwm tshwj xeeb rau nws. Qhov no yuav tsum tau saib kom meej ntxiv.
YLub tswvyim ntawm nucleic acids
Txhua cov nucleic acids (DNA thiab RNA) yog cov tshuaj lom neeg muaj sia nyob uas sib txawv ntawm cov saw hlau. DNA yog ob-stranded polymer molecule uas muajCov ntaub ntawv keeb kwm ntawm cov kab mob eukaryotic. Lub voj voog DNA molecules yuav muaj cov ntaub ntawv keeb kwm ntawm qee tus kab mob. Cov no yog HIV thiab adenoviruses. Kuj tseem muaj 2 hom DNA tshwj xeeb: mitochondrial thiab plastid (pom hauv chloroplasts).
RNA, ntawm qhov tod tes, muaj ntau ntau hom, vim muaj cov haujlwm sib txawv ntawm nucleic acid. Muaj nuclear RNA, uas muaj cov ntaub ntawv keeb kwm ntawm cov kab mob thiab cov kab mob feem ntau, matrix (los yog messenger RNA), ribosomal thiab thauj. Tag nrho cov ntawm lawv tau koom nrog hauv kev khaws cov ntaub ntawv keeb kwm yav dhau los lossis hauv kev qhia gene. Txawm li cas los xij, nws yuav tsum tau nkag siab ntau ntxiv txog dab tsi ua haujlwm nucleic acids ua hauv cell.
Ob npaug tso tseg DNA molecule
Hom DNA no yog qhov chaw khaws cia zoo meej rau cov ntaub ntawv keeb kwm yav dhau los. Ib ob-stranded DNA molecule yog ib qho molecule uas tsim los ntawm heterogeneous monomers. Lawv txoj hauj lwm yog tsim hydrogen bonds ntawm nucleotides ntawm lwm cov saw hlau. DNA monomer nws tus kheej muaj nitrogenous puag, ib qho orthophosphate residue, thiab tsib-carbon monosaccharide deoxyribose. Nyob ntawm seb hom nitrogenous puag yog ib qho DNA monomer, nws muaj nws lub npe. Hom DNA monomers:
- deoxyribose nrog ib qho orthophosphate residue thiab adenyl nitrogenous puag;
- thymidine nitrogenous puag nrog deoxyribose thiab ib qho orthophosphate residue;
- cytosine nitrogen puag, deoxyribose thiab orthophosphate residue;
- orthophosphate nrog deoxyribose thiab guanine nitrogenous residue.
Hauv kev sau ntawv, txhawm rau ua kom yooj yim cov qauv DNA, cov adenyl residue yog "A", guanine residue yog "G", thymidine residue yog "T", thiab cytosine residue yog "C. ". Nws yog ib qho tseem ceeb uas cov ntaub ntawv genetic hloov los ntawm ob-stranded DNA molecule mus rau messenger RNA. Nws muaj ob peb qhov sib txawv: ntawm no, raws li cov carbohydrate residue, tsis muaj deoxyribose, tab sis ribose, thiab es tsis txhob ntawm thymidyl nitrogenous puag, uracil tshwm sim hauv RNA.
qauv thiab kev ua haujlwm ntawm DNA
DNA yog tsim los ntawm lub hauv paus ntsiab lus ntawm cov khoom siv roj ntsha polymer, uas ib lub saw hlau tau tsim ua ntej raws li tus qauv muab, nyob ntawm seb cov ntaub ntawv caj ces ntawm niam txiv ntawm tes. DNA nucleotides txuas ntawm no los ntawm covalent bonds. Tom qab ntawd, raws li lub hauv paus ntsiab lus ntawm complementarity, lwm cov nucleotides txuas nrog rau cov nucleotides ntawm ib leeg-stranded molecule. Yog hais tias nyob rau hauv ib leeg-stranded molecule qhov pib yog sawv cev los ntawm nucleotide adenine, ces nyob rau hauv lub thib ob (complementary) saw nws yuav sib haum mus rau thymine. Guanine yog complementary rau cytosine. Yog li, ib ob-stranded DNA molecule yog tsim. Nws yog nyob rau hauv lub nucleus thiab khaws cov ntaub ntawv keeb kwm, uas yog encoded los ntawm codons - triplets ntawm nucleotides. Ob-stranded DNA ua haujlwm:
- khaws cia cov ntaub ntawv keeb kwm tau txais los ntawm niam txiv ntawm tes;
- gene expression;
- tiv thaiv kev hloov pauv.
YQhov tseem ceeb ntawm cov proteins thiab nucleic acids
Nws ntseeg tau tias kev ua haujlwm ntawm cov protein thiab nucleic acids muaj ntau, uas yog:lawv koom nrog hauv kev qhia gene. Cov nucleic acid nws tus kheej yog lawv qhov chaw cia, thiab cov protein yog qhov kawg ntawm kev nyeem cov ntaub ntawv los ntawm cov noob. Cov noob nws tus kheej yog ib feem ntawm ib qho tseem ceeb DNA molecule, ntim rau hauv chromosome, uas cov ntaub ntawv hais txog cov qauv ntawm qee cov protein tau sau tseg los ntawm nucleotides. Ib lub noob lej rau cov amino acid ib ntus ntawm ib qho protein. Nws yog cov protein uas yuav siv cov ntaub ntawv keeb kwm yav dhau los.
Kev faib tawm ntawm RNA hom
Lub luag haujlwm ntawm nucleic acids hauv cell muaj ntau haiv neeg. Thiab lawv muaj ntau heev nyob rau hauv rooj plaub ntawm RNA. Txawm li cas los xij, qhov multifunctionality no tseem yog txheeb ze, vim tias ib hom RNA yog lub luag haujlwm rau ib qho ntawm cov haujlwm. Hauv qhov no, muaj cov nram qab no hom RNA:
- nuclear RNA ntawm cov kab mob thiab cov kab mob;
- matrix (cov ntaub ntawv) RNA;
- ribosomal RNA;
- messenger RNA plasmid (chloroplast);
- Chloroplast ribosomal RNA;
- mitochondrial tub txib RNA;
- transfer RNA.
Ymitochondrial ribosomal RNA;
RNA Functions
Kev faib tawm no muaj ntau hom RNA, uas tau muab faib nyob ntawm qhov chaw. Txawm li cas los xij, hauv cov ntsiab lus ua haujlwm, lawv yuav tsum tau muab faib ua 4 hom: nuclear, xov xwm, ribosomal thiab thauj. Kev ua haujlwm ntawm ribosomal RNA yog protein synthesis raws li nucleotide ib ntus ntawm tus xa xov RNA. Qhov twgamino acids yog "nqa" mus rau ribosomal RNA, "strung" ntawm tus xa xov RNA, los ntawm kev thauj ribonucleic acid. Qhov no yog li cas synthesis tshwm sim hauv txhua yam kabmob uas muaj ribosomes. Cov qauv thiab kev ua haujlwm ntawm nucleic acids muab ob qho tib si khaws cia ntawm cov khoom siv caj ces thiab tsim cov txheej txheem protein synthesis.
YMitochondrial nucleic acids
Yog tias yuav luag txhua yam paub txog kev ua haujlwm hauv lub cell ua los ntawm nucleic acids nyob hauv lub nucleus lossis cytoplasm, ces tseem muaj cov ntaub ntawv me ntsis txog mitochondrial thiab plastid DNA. Tshwj xeeb ribosomal thiab tub txib RNAs kuj tau pom ntawm no. Nucleic acids DNA thiab RNA muaj nyob ntawm no txawm nyob hauv cov kab mob autotrophic tshaj plaws.
Tej zaum cov nucleic acid nkag mus rau hauv lub cell los ntawm symbiogenesis. Txoj kev no yog suav tias yog cov kws tshawb fawb feem ntau yog vim tsis muaj lwm txoj kev piav qhia. Cov txheej txheem yog xam raws li nram no: ib tug symbiotic autotrophic kab mob nkag mus rau hauv lub cell ntawm ib lub sij hawm. Raws li qhov tshwm sim, lub cell tsis muaj nuclear nyob hauv lub cell thiab muab lub zog, tab sis maj mam degrades.
Thaum thawj theem ntawm evolutionary txoj kev loj hlob, tej zaum, ib tug symbiotic non-nuclear kab mob tsiv mus rau kev hloov pauv nyob rau hauv lub nucleus ntawm tus tswv tsev cell. Qhov no tso cai rau cov noob ua lub luag haujlwm khaws cia cov ntaub ntawv hais txog cov qauv ntawm mitochondrial proteins kom nkag mus rau hauv nucleic acid ntawm tus tswv tsev cell. Txawm li cas los xij, rau tam sim no, dab tsi ua haujlwm hauv cell ua los ntawm nucleic acids ntawm mitochondrial keeb kwm,tsis muaj ntaub ntawv ntau.
Tej zaum, qee cov proteins tau tsim nyob rau hauv mitochondria, cov qauv uas tseem tsis tau nkag los ntawm tus tswv tsev lub DNA lossis RNA. Nws kuj tseem zoo li lub xov tooj ntawm tes xav tau nws tus kheej cov txheej txheem ntawm cov protein synthesis nkaus xwb vim tias ntau cov proteins uas tsim los hauv cytoplasm tsis tuaj yeem nkag los ntawm ob daim nyias nyias ntawm mitochondria. Nyob rau tib lub sijhawm, cov organelles tsim lub zog, thiab yog li ntawd, yog tias muaj cov channel lossis cov khoom thauj tshwj xeeb rau cov protein, nws yuav txaus rau kev txav ntawm cov molecules thiab tawm tsam cov concentration gradient.
Plasmid DNA thiab RNA
Plastids (chloroplasts) kuj muaj lawv tus kheej DNA, uas yog lub luag haujlwm rau kev siv cov haujlwm zoo sib xws, ib yam li cov mitochondrial nucleic acids. Nws kuj muaj nws tus kheej ribosomal, tub txib thiab hloov RNA. Ntxiv mus, plastids, txiav txim los ntawm tus naj npawb ntawm daim nyias nyias, thiab tsis yog los ntawm tus naj npawb ntawm cov tshuaj biochemical, yog qhov nyuaj dua. Nws tshwm sim tias ntau plastids muaj 4 txheej ntawm daim nyias nyias, uas tau piav qhia los ntawm cov kws tshawb fawb sib txawv.
Ib yam yog qhov pom tseeb: kev ua haujlwm ntawm nucleic acids hauv lub cell tseem tsis tau kawm tiav. Nws tsis paub tias qhov tseem ceeb ntawm mitochondrial protein-synthesizing system thiab cov kab ke chloroplastic analogous muaj. Nws kuj tseem tsis paub meej tias yog vim li cas hlwb xav tau mitochondrial nucleic acids yog tias cov proteins (tsis yog tag nrho) twb tau encoded hauv nuclear DNA (los yog RNA, nyob ntawm seb lub cev). Txawm hais tias qee qhov tseeb yuam peb kom pom zoo tias cov protein-synthesizing system ntawm mitochondria thiab chloroplasts yog lub luag haujlwm rau tib lub luag haujlwm xws lithiab DNA ntawm nucleus thiab RNA ntawm cytoplasm. Lawv khaws cov ntaub ntawv keeb kwm yav dhau los, tsim tawm thiab xa mus rau cov menyuam ntxhais.
CV
Nws yog ib qho tseem ceeb kom nkag siab txog dab tsi ua haujlwm hauv cell ua nucleic acids ntawm nuclear, plastid thiab mitochondrial keeb kwm. Qhov no qhib rau ntau qhov kev cia siab rau kev tshawb fawb, vim hais tias cov txheej txheem symbiotic, raws li muaj ntau yam kab mob autotrophic tshwm sim, tuaj yeem tsim tawm hnub no. Qhov no yuav ua rau kom tau txais ib hom tshiab ntawm tes, tej zaum txawm tias tib neeg. Txawm hais tias nws tseem ntxov dhau los tham txog qhov kev cia siab rau kev qhia txog ntau lub membrane plastid organelles rau hauv cov hlwb.
Nws yog qhov tseem ceeb dua kom nkag siab tias nucleic acids yog lub luag haujlwm rau yuav luag txhua cov txheej txheem hauv lub cell. Qhov no yog ob qho tib si protein biosynthesis thiab khaws cia cov ntaub ntawv hais txog cov qauv ntawm tes. Tsis tas li ntawd, nws tseem ceeb heev uas cov nucleic acids ua haujlwm ntawm kev hloov cov khoom siv los ntawm niam txiv mus rau cov menyuam ntxhais. Qhov no lav qhov kev txhim kho ntxiv ntawm cov txheej txheem evolutionary.
