Lub sijhawm peb nyob yog cim los ntawm kev hloov pauv zoo, kev vam meej loj, thaum tib neeg tau txais cov lus teb rau cov lus nug tshiab thiab ntau ntxiv. Lub neej yog sai sai mus rau pem hauv ntej, thiab dab tsi txog thaum nyuam qhuav zoo li tsis yooj yim sua yog pib los muaj tseeb. Nws yog qhov ua tau heev tias qhov zoo li niaj hnub no yog ib zaj dab neeg los ntawm cov ntawv tseeb tseeb yuav sai sai no kuj tau txais cov yam ntxwv ntawm kev muaj tiag.
Ib qhov kev tshawb pom tseem ceeb tshaj plaws nyob rau hauv ib nrab ntawm lub xyoo pua nees nkaum yog cov nucleic acids RNA thiab DNA, ua tsaug rau tus txiv neej los ze zog rau unraveling lub mysteries ntawm xwm.
Nucleic acids
Nucleic acids yog cov organic tebchaw nrog macromolecular zog. Lawv muaj xws li hydrogen, carbon, nitrogen thiab phosphorus.
Lawv tau tshawb pom xyoo 1869 los ntawm F. Miescher, uas kuaj cov kua paug. Txawm li cas los xij, lub sijhawm ntawd nws qhov kev tshawb pom tsis tau muab qhov tseem ceeb ntau. Tsuas yog tom qab ntawd, thaum cov kua qaub no tau pom nyob rau hauv tag nrho cov tsiaj txhu thiab cov nroj tsuag, puas nkag siab txog lawv lub luag haujlwm loj tuaj.
Muaj ob hom nucleic acids: RNA thiab DNA (ribonucleic thiab deoxyribonucleicacids). Kab lus no yog hais txog ribonucleic acid, tab sis rau kev nkag siab dav dav, peb kuj xav txog dab tsi DNA yog.
Deoxyribonucleic acid yog dab tsi?
DNA yog ib qho nucleic acid uas muaj ob txoj hlua uas txuas nrog raws li txoj cai ntawm kev sib txuas los ntawm hydrogen bonds ntawm nitrogenous bases. Cov saw ntev yog twisted rau hauv ib lub kauv, ib tig muaj yuav luag kaum nucleotides. Txoj kab uas hla ntawm ob lub helix yog ob millimeters, qhov deb ntawm nucleotides yog li ntawm ib nrab nanometer. Qhov ntev ntawm ib lub molecule qee zaum nce mus txog ob peb centimeters. Qhov ntev ntawm DNA ntawm lub nucleus ntawm tib neeg lub cell yog yuav luag ob meters.
Tus qauv ntawm DNA muaj tag nrho cov ntaub ntawv caj ces. DNA muaj replication, uas txhais tau hais tias cov txheej txheem thaum lub sij hawm uas ob tug zoo tib yam tus ntxhais molecules yog tsim los ntawm ib tug molecule.
Raws li twb tau sau tseg lawm, cov saw hlau yog tsim los ntawm nucleotides, uas nyob rau hauv lem muaj nitrogenous bases (adenine, guanine, thymine thiab cytosine) thiab phosphorus acid residue. Tag nrho cov nucleotides sib txawv hauv cov hauv paus nitrogenous. Hydrogen bonding tsis tshwm sim ntawm txhua lub hauv paus; adenine, piv txwv li, tuaj yeem ua ke nrog thymine lossis guanine. Yog li, muaj ntau li adenyl nucleotides nyob rau hauv lub cev li thymidyl nucleotides, thiab tus naj npawb ntawm guanyl nucleotides yog sib npaug rau cytidyl nucleotides (Chargaff txoj cai). Nws hloov tawm hais tias qhov sib lawv liag ntawm ib txoj saw predetermines qhov sib lawv liag ntawm lwm tus, thiab cov chains zoo li iav ib leeg. Xws li ib tug qauv, qhov twg cov nucleotides ntawm ob chains yog teem nyob rau hauv ib qho kev txiav txim, thiab tseem txuas nrog xaiv, yog hu ualub hauv paus ntsiab lus ntawm complementarity. Ntxiv nrog rau cov tshuaj hydrogen, ob lub helix kuj cuam tshuam nrog hydrophobically.
Ob txoj saw hlau nyob rau hauv qhov kev taw qhia, uas yog, lawv nyob rau hauv cov lus qhia. Yog li ntawd, opposite peb'-kawg ntawm ib tug yog tsib'-kawg ntawm lwm txoj saw.
Outwardly, DNA molecule zoo li tus kauv staircase, railing ntawm uas yog qab zib-phosphate qaum qaum, thiab cov kauj ruam yog complementary nitrogen bases.
ribonucleic acid yog dab tsi?
RNA yog nucleic acid nrog monomers hu ua ribonucleotides.
Hauv cov khoom siv tshuaj, nws zoo ib yam li DNA, vim tias ob qho tib si yog cov polymers ntawm nucleotides, uas yog phosphorylated N-glycoside, uas yog tsim los ntawm pentose (tsib-carbon qab zib) residue, nrog phosphate pawg ntawm thib tsib carbon atom thiab nitrogen puag ntawm thawj carbon atom.
Nws yog ib txoj hlua polynucleotide (tshwj tsis yog cov kab mob), uas luv dua li DNA.
Ib RNA monomer yog cov seem ntawm cov tshuaj hauv qab no:
- nitrogen bases;
- tsib-carbon monosaccharide;
- phosphorus acids.
RNAs muaj pyrimidine (uracil thiab cytosine) thiab purine (adenine, guanine) hauv paus. Ribose yog monosaccharide ntawm RNA nucleotide.
Qhov txawv ntawm RNA thiab DNA
Nucleic acids txawv ntawm ib leeg hauv cov hauv qab no:
- nws qhov ntau npaum li cas hauv lub cell nyob ntawm lub cev lub cev, hnub nyoog thiab kev koom tes hauv lub cev;
- DNA muaj cov carbohydratesdeoxyribose, thiab RNA - ribose;
- Lub hauv paus nitrogenous hauv DNA yog thymine, thiab hauv RNA nws yog uracil;
- cov chav kawm ua haujlwm sib txawv, tab sis raug tsim los ntawm DNA matrix;
- DNA yog ob lub helix, RNA yog ib txoj hlua;
- tsis raug rau nws txoj cai DNA Chargaff;
- RNA muaj ntau lub hauv paus me;
- chains txawv qhov ntev.
Study history
RNA cell yog thawj zaug pom los ntawm German biochemist R. Altman thaum kawm cov poov xab. Nyob rau hauv nruab nrab ntawm lub xyoo pua nees nkaum, lub luag hauj lwm ntawm DNA nyob rau hauv noob caj noob ces muaj pov thawj. Tsuas yog tom qab ntawd yog RNA hom, kev ua haujlwm, thiab lwm yam piav qhia. Txog li 80-90% ntawm qhov loj hauv lub cell poob ntawm rRNA, uas ua ke nrog cov proteins tsim cov ribosome thiab koom nrog cov protein biosynthesis.
Nyob rau xyoo pua xyoo dhau los, thawj zaug tau hais tias yuav tsum muaj qee yam tsiaj uas nqa cov ntaub ntawv caj ces rau kev tsim cov protein. Tom qab ntawd, nws tau tshawb fawb pom tias muaj cov ntaub ntawv xov xwm ribonucleic acids sawv cev rau cov ntawv luam ntawm cov noob. Lawv tseem hu ua tub txib RNAs.
Lub npe hu ua thauj cov kua qaub yog koom nrog hauv kev txiav txim siab cov ntaub ntawv sau tseg hauv lawv.
Tom qab ntawd, txoj hauv kev tau pib tsim los txheeb xyuas cov kab ke ntawm nucleotides thiab tsim cov qauv ntawm RNA hauv qhov chaw acid. Yog li nws tau pom tias qee qhov ntawm lawv, uas yog hu ua ribozymes, tuaj yeem tshem cov chains polyribonucleotide. Yog li ntawd, nws pib xav tias thaum lub sij hawm lub neej tau tshwm sim nyob rau hauv lub ntiaj teb no,RNA ua haujlwm tsis muaj DNA thiab cov proteins. Ntxiv mus, tag nrho cov kev hloov pauv tau ua nrog nws kev koom tes.
Tus qauv ntawm ribonucleic acid molecule
Yuav luag txhua RNAs yog ib txoj hlua ntawm polynucleotides, uas, dhau los, muaj monoribonucleotides - purine thiab pyrimidine bases.
Nucleotides yog txhais los ntawm cov tsiaj ntawv thawj zaug ntawm lub hauv paus:
- adenine (A), A;
- guanine (G), G;
- cytosine (C), C;
- uracil (U), U.
Lawv txuas los ntawm peb-thiab tsib-phosphodiester bonds.
Cov nucleotides sib txawv tshaj plaws (los ntawm ntau kaum txog kaum txhiab) suav nrog hauv cov qauv ntawm RNA. Lawv tuaj yeem tsim cov qauv theem nrab uas feem ntau yog luv ob-stranded strands uas yog tsim los ntawm cov hauv paus ntxiv.
qauv ntawm ribnucleic acid molecule
Raws li twb tau hais lawm, cov molecule muaj ib txoj kab sib txuas. RNA tau txais nws cov qauv theem nrab thiab cov duab los ntawm kev sib cuam tshuam ntawm nucleotides nrog ib leeg. Nws yog ib qho polymer uas nws monomer yog nucleotide uas muaj suab thaj, phosphorus acid residue thiab nitrogen hauv paus. Outwardly, lub molecule zoo ib yam li ib tug ntawm cov DNA chains. Nucleotides adenine thiab guanine, uas yog ib feem ntawm RNA, yog purine. Cytosine thiab uracil yog pyrimidine bases.
txheej txheem txheej txheem
Rau RNA molecule los ua ke, tus qauv yog DNA molecule. Muaj tseeb, cov txheej txheem thim rov qab kuj tshwm sim, thaum cov molecules tshiab ntawm deoxyribonucleic acid raug tsim ntawm ribonucleic acid matrix. Xws litshwm sim thaum lub sijhawm rov ua dua ntawm qee yam kab mob.
Lub hauv paus rau biosynthesis tseem tuaj yeem ua lwm yam molecules ntawm ribonucleic acid. Nws cov ntawv sau, uas tshwm sim hauv lub cell nucleus, suav nrog ntau cov enzymes, tab sis qhov tseem ceeb ntawm lawv yog RNA polymerase.
Views
Nyob ntawm hom RNA, nws txoj haujlwm kuj txawv. Muaj ntau hom:
- xov xwm i-RNA;
- ribosomal rRNA;
- thauj t-RNA;
- me me;
- ribozymes;
- viral.
Cov ntaub ntawv Ribonucleic Acid
Cov molecules no kuj hu ua matrix. Lawv tsim txog li ob feem pua ntawm tag nrho hauv lub cell. Nyob rau hauv eukaryotic hlwb, lawv yog synthesized nyob rau hauv lub nuclei ntawm DNA templates, ces dhau mus rau hauv lub cytoplasm thiab khi rau ribosomes. Tsis tas li ntawd, lawv dhau los ua qauv rau kev tsim cov protein: lawv tau koom nrog kev hloov RNAs uas nqa cov amino acids. Qhov no yog li cas cov txheej txheem ntawm kev hloov pauv cov ntaub ntawv yuav siv qhov chaw, uas tau pom nyob rau hauv cov qauv tshwj xeeb ntawm cov protein. Hauv qee tus kab mob RNAs, nws kuj yog chromosome.
Jacob thiab Mano yog cov neeg nrhiav pom ntawm hom no. Tsis muaj cov qauv nruj, nws cov saw hlau ua cov voj voog nkhaus. Tsis ua hauj lwm, i-RNA sib sau ua ke thiab folds rau hauv lub pob, thiab nthuav dav hauv kev ua haujlwm.
i-RNA nqa cov ntaub ntawv hais txog qhov sib lawv liag ntawm cov amino acids hauv cov protein uas tau tsim los. Txhua amino acid yog encoded nyob rau hauv ib qho chaw tshwj xeeb uas siv cov cim caj ces yog:
- tripletity - los ntawm plaub lub mononucleotides tuaj yeem tsim rau caum-plaub codons (genetic code);
- tsis hla - cov ntaub ntawv txav mus rau hauv ib qho kev coj;
- txuas ntxiv - lub hauv paus ntsiab lus ntawm kev ua haujlwm yog tias ib mRNA yog ib qho protein;
- universality - ib los yog lwm hom amino acid yog encoded nyob rau hauv tag nrho cov kab mob nyob rau hauv tib txoj kev;
- degeneracy - nees nkaum amino acids paub, thiab rau caum-ib codons, uas yog, lawv tau encoded los ntawm ob peb kab zauv.
YRibosomal ribonucleic acid
Cov molecules no ua rau feem coob ntawm cellular RNA, uas yog yim caum txog cuaj caum feem pua ntawm tag nrho. Lawv ua ke nrog cov proteins thiab tsim ribosomes - cov no yog cov organelles ua cov protein synthesis.
Ribosomes yog rau caum-tsib feem pua rRNA thiab peb caug-tsib feem pua ntawm cov protein. Qhov no polynucleotide saw yooj yim folds nrog rau cov protein.
Lub ribosome muaj cov amino acid thiab peptide cheeb tsam. Lawv nyob ntawm qhov chaw tiv tauj.
Ribosomes txav mus rau hauv lub cell, ua ke cov proteins nyob rau hauv qhov chaw. Lawv tsis yog qhov tshwj xeeb thiab tuaj yeem tsis tsuas yog nyeem cov ntaub ntawv los ntawm mRNA, tab sis kuj tsim cov matrix nrog lawv.
Kev thauj ribonucleic acid
t-RNA yog qhov kev kawm tshaj plaws. Lawv tsim txog kaum feem pua ntawm cov cellular ribonucleic acid. Cov hom RNA no khi rau cov amino acids ua tsaug rau cov enzyme tshwj xeeb thiab xa mus rau ribosomes. Nyob rau tib lub sijhawm, cov amino acids raug thauj los ntawm kev thauj mus losmolecules. Txawm li cas los xij, nws tshwm sim qhov sib txawv codons code rau cov amino acid. Ces ob peb thauj RNAs yuav nqa lawv.
Nws curls mus rau hauv lub pob thaum tsis ua haujlwm, tab sis ua haujlwm zoo li cloverleaf.
Cov ntu hauv qab no yog qhov txawv ntawm nws:
- tus txais qia muaj cov nucleotide sib lawv liag ntawm ACC;
- site rau txuas rau ribosome;
- an anticodon encoding cov amino acid txuas rau no tRNA.
hom me me ntawm ribonucleic acid
Tsis ntev los no, hom RNA tau rov ua dua tshiab nrog chav kawm tshiab, hu ua RNA me me. Lawv feem ntau yuav yog cov tswj hwm thoob ntiaj teb uas tig cov noob rau lossis tawm hauv kev loj hlob embryonic, nrog rau kev tswj cov txheej txheem hauv hlwb.
Ribozymes kuj tau txheeb xyuas tsis ntev los no, lawv tau koom nrog thaum RNA acid yog fermented, ua raws li catalyst.
Viral hom acids
Tus kab mob tuaj yeem muaj ribonucleic acid lossis deoxyribonucleic acid. Yog li ntawd, nrog rau cov khoom sib xws, lawv hu ua RNA-muaj. Thaum tus kab mob no nkag mus rau hauv lub xovtooj ntawm tes, qhov kev hloov pauv rov qab tshwm sim - DNA tshiab tshwm sim los ntawm ribonucleic acid, uas tau koom ua ke rau hauv cov hlwb, ua kom ntseeg tau tias muaj tus kab mob thiab rov ua dua tshiab. Hauv lwm qhov xwm txheej, kev tsim cov RNA sib xyaw ua ke tshwm sim ntawm RNA tuaj. Cov kab mob yog cov proteins, cov haujlwm tseem ceeb thiab kev tsim tawm mus ntxiv yam tsis muaj DNA, tab sis tsuas yog raws li cov ntaub ntawv muaj nyob hauv RNA ntawm tus kab mob.
Replication
txhawm rau txhim kho kev nkag siab zoo, nws yog qhov tsim nyogXav txog cov txheej txheem ntawm kev rov ua dua tshiab uas ua rau ob qho tib si nucleic acid molecules. Nov yog qhov kev faib cell pib.
Nws suav nrog DNA polymerases, DNA-dependent, RNA polymerases thiab DNA ligases.
Cov txheej txheem rov ua dua muaj cov kauj ruam hauv qab no:
- despiralization - muaj qhov sib txawv ntawm cov niam txiv DNA, ntes tag nrho cov molecule;
- tawg ntawm hydrogen daim ntawv cog lus, nyob rau hauv uas chains diverge, thiab ib tug replication diav rawg tshwm;
- kho ntawm dNTPs rau cov hauv paus tso tawm ntawm niam txiv chains;
- cleavage ntawm pyrophosphates los ntawm dNTP molecules thiab tsim ntawm phosphorodiester bonds vim tso tawm zog;
- respiralization.
Tom qab tsim ntawm tus ntxhais molecule, lub nucleus, cytoplasm thiab lwm yam tau muab faib. Yog li, ob tug ntxhais lub hlwb raug tsim uas tau txais tag nrho cov ntaub ntawv ntawm caj ces.
Tsis tas li ntawd, cov qauv tseem ceeb ntawm cov proteins uas yog synthesized hauv cell yog encoded. DNA siv ib feem ntawm txoj kev no, thiab tsis ncaj qha, uas muaj nyob rau hauv lub fact tias nws yog nyob rau hauv DNA uas lub synthesis ntawm cov proteins, RNA koom nyob rau hauv tsim, yuav siv sij hawm qhov chaw. Cov txheej txheem no hu ua transcription.
Kev txhais lus
Qhov kev sib txuas ntawm tag nrho cov molecules tshwm sim thaum lub sijhawm sau ntawv, uas yog, rov sau cov ntaub ntawv caj ces los ntawm ib qho DNA operon tshwj xeeb. Cov txheej txheem zoo ib yam li kev rov ua dua tshiab hauv qee txoj kev, thiab txawv ntawm lwm tus.
Qhov zoo sib xws yog cov hauv qab no:
- pib nrog DNA despiralization;
- hydrogen rupture tshwm simkev sib txuas ntawm lub hauv paus ntawm cov chains;
- NTFs ntxiv rau lawv;
- hydrogen bonds yog tsim.
Qhov txawv ntawm kev rov ua dua:
- thaum lub sijhawm sau ntawv, tsuas yog ib feem ntawm DNA sib raug rau cov ntawv sau tseg tsis raug, thaum lub sijhawm rov ua dua, tag nrho cov molecule yog untwisted;
- thaum sau ntawv, tunable NTFs muaj ribose, thiab uracil es tsis txhob thymine;
- cov ntaub ntawv yog sau tawm tsuas yog los ntawm ib cheeb tsam;
- tom qab tsim cov molecule, cov hydrogen bonds thiab cov saw hlau sib txuas tau tawg, thiab cov saw txuas tawm ntawm DNA.
Rau kev ua haujlwm ib txwm muaj, thawj cov qauv ntawm RNA yuav tsum tsuas yog muaj cov DNA seem uas tau theej los ntawm exons.
Cov txheej txheem maturation pib hauv RNA tsim tshiab. Cov cheeb tsam uas ntsiag to yog excised, thiab cov cheeb tsam cov ntaub ntawv yog fused los ua ib tug polynucleotide saw. Tsis tas li ntawd, txhua hom muaj nws qhov kev hloov pauv.
Nyob hauv i-RNA, txuas rau qhov pib kawg tshwm sim. Polyadenylate txuas mus rau qhov chaw kawg.
TRNA hauv paus raug hloov kho los ua hom me.
Nyob rau hauv rRNA, tus kheej lub hauv paus kuj yog methylated.
Tiv thaiv cov protein los ntawm kev puas tsuaj thiab txhim kho kev thauj mus rau cytoplasm. Mature RNA khi rau lawv.
Qhov tseem ceeb ntawm deoxyribonucleic thiab ribonucleic acids
Nucleic acids yog qhov tseem ceeb hauv lub neej ntawm cov kab mob. Nws tau khaws cia rau hauv lawv, pauv mus rau cytoplasm thiab tau txais los ntawm cov menyuam ntxhaiscov ntaub ntawv hais txog cov proteins synthesized hauv txhua lub cell. Lawv muaj nyob rau hauv tag nrho cov kab mob nyob, kev ruaj ntseg ntawm cov kua qaub no ua lub luag haujlwm tseem ceeb rau kev ua haujlwm ntawm ob lub hlwb thiab tag nrho cov kab mob. Txhua qhov kev hloov pauv hauv lawv cov qauv yuav ua rau kev hloov pauv ntawm tes.
