Nucleotide - dab tsi yog qhov no? Muaj pes tsawg leeg, qauv, xov tooj thiab sib lawv liag ntawm nucleotides nyob rau hauv lub DNA saw

Tag nrho lub neej nyob rau lub ntiaj chaw yog muaj li ntawm ntau hlwb uas pab txhawb lub ordering ntawm lawv lub koom haum ntawm cov nuj nqis uas muaj nyob rau hauv lub nucleus ntawm cov kev tshuaj ntsuam genetic ntaub ntawv. Nws yog tseem tam sim no, siv thiab kis complex macromolecular tebchaw - ib tug nucleic acid muaj lub monomer units - nucleotides. nws yog tsis yooj yim sua rau overestimate lub luag hauj lwm ntawm nucleic acids. Stability ntawm lawv lug txiav txim los ntawm lub cev tau hauj lwm ntawm tus kab mob, thiab tej deviations nyob rau hauv cov qauv yuav inevitably ua rau kev hloov nyob rau hauv cellular lub koom haum, kev ua ntawm physiological dab thiab cov nqi ntawm hlwb nyob rau hauv kev.

Lub tswvyim ntawm ib tug nucleotide thiab nws cov khoom

Txhua molecule ntawm DNA los yog RNA yog ua los ntawm me me monomeric tebchaw - nucleotide. Nyob rau hauv lwm yam lus, cov nucleotides - lub tsev blocks ntawm nucleic acids, co-enzymes thiab lwm yam lom tebchaw, uas yog ib qho tseem ceeb rau ntawm tes thaum lub sij hawm nws lub neej.

Lub ntsiab thaj chaw ntawm cov tseem ceeb tshuaj muaj xws li:

• cia ntawm cov ntaub ntawv hais txog cov protein qauv thiab pub sijhawm;
• Tswj ntau tshaj qhov kev loj hlob thiab tu tub tu kiv;
• koom nyob rau hauv lub metabolism thiab ntau lwm physiological dab nyob rau hauv lub cell.

Muaj pes tsawg leeg ntawm lub nucleotides

Hais txog nucleotides, peb yuav tsis nyob rau tej qho tseem ceeb heev qhov teeb meem raws li lawv cov qauv thiab muaj pes tsawg leeg.

Txhua nucleotide muaj:

• qab zib residue;
• nitrogenous puag;
• phosphate pab pawg neeg los yog ib tug residue ntawm phosphoric acid.

Peb yuav hais tias qhov nucleotide - ib tug complex organic compound. Nyob ntawm seb cov kev muaj pes tsawg leeg thiab hom nitrogenous bases nyob rau hauv lub nucleotide pentose nucleic acid qauv subdivided rau hauv:

• deoxyribonucleic acid los yog DNA;
• ribonucleic acid, los yog RNA.

Muaj pes tsawg leeg nucleic acid

Lub nucleic kua qaub-pentose qab zib no. Qhov no tsib-carbon qab zib nyob rau hauv lub DNA nws yog hu ua deoxyribose, nyob rau hauv RNA - ribose. Txhua molecule muaj pentoses tsib carbon atoms, plaub uas ua ke nrog cov pa atom tsim ib tug tsib-membered nplhaib, thiab lub thib tsib yog ib feem ntawm lub HO-CH2 pab pawg neeg.

Cov hauj lwm ntawm txhua carbon atom nyob rau hauv lub molecule pentose denoted Arabic tus nab npawj nrog ib tug prime (1C ', 2C', 3 c ', 4C', 5C '). Txij li thaum tag nrho cov dab nyeem ntawv ntawm kev tshuaj ntsuam genetic ntaub ntawv nrog nucleic acid molecules muaj ib tug nruj directivity, lub numbering ntawm cov pa roj carbon atoms thiab lawv kev kho nyob rau hauv lub nplhaib ua ib tug pointer rau qhov tseeb coj.

Lub hydroxyl pab pawg neeg mus rau lub thib peb thiab thib tsib carbon atoms (thiab 3S '5') daim ntawv phosphoric acid residue. Nws txiav txim cov tshuaj yog leejtwg ntawm DNA thiab RNA mus rau ib tug pab pawg neeg ntawm acids.

Tus thawj carbon atom (1S ') nitrogenous puag txuas mus rau lub qab zib molecule.

Hom muaj pes tsawg leeg nitrogenous bases

Nucleotides ntawm DNA nitrogenous bases uas muaj los ntawm plaub hom:

• adenine (A);
• guanine (G);
• cytosine (C);
• thymine (T).

Thawj ob mus rau lub chav kawm ntawv ntawm purines, ob lub xeem - pyrimidine. Molecular hnyav purine pyrimidine yog yeej ib txwm hnyav zog.

Nucleotides RNA nitrogenous bases sawv cev:

• adenine (A);
• guanine (G);
• cytosine (C);
• uracil (U).

Uracil raws li thymine, ib tug pyrimidine puag.

Nyob rau hauv cov ntawv nyeem thiab yuav feem ntau nrhiav tau lwm los nitrogenous bases - Latin ntawv (A, T, C, G, U).

Greater nthuav dav cov tshuaj qauv ntawm purines thiab pyrimidines.

Pyrimidines, namely, cytosine, thymine thiab uracil, nyob rau hauv cov qauv sawv cev los ntawm ob nitrogen atoms thiab plaub carbon atoms txoj kev ib tug rau membered nplhaib. Txhua atom nws muaj nws tus kheej tooj ntawm 1 mus rau 6.

Purines (adenine thiab guanine) muaj pyrimidine thiab imidazole los yog ob tug heterocycles. Molecule purine bases sawv cev los ntawm plaub nitrogen atoms thiab tsib carbon atoms. Txhua atom numbered los 1 mus rau 9.

Cov uas ua compound ntawm nitrogenous puag thiab tus pentose residue tsim nucleoside. Nucleotide - ib tug nucleoside compound thiab ib tug phosphate pab pawg neeg.

Cov tsim ntawm phosphodiester bonds

Nws yog ib qho tseem ceeb kom nkag siab txog cov nqe lus nug ntawm yuav ua li cas mus ua ke lub nucleotides nyob rau hauv lub polypeptide saw tsim tau ib cov nucleic acid molecule. Qhov no tshwm sim vim qhov thiaj li hu ua phosphodiester bonds.

Sis ntawm ob nucleotides muab dinucleotide. Tsim tshiab tebchaw tshwm sim los ntawm cov hws raws li ntawm lub phosphate residue ntawm ib tug monomer thiab lwm hydroxy pentose phosphodiester daim ntawv cog lus no tshwm sim.

Polynucleotide synthesis - rov repetition ntawm no cov tshuaj tiv thaiv (ob peb lab lub sij hawm). Ib tug polynucleotide saw yog tsim los ntawm txoj kev ua phosphodiester bonds ntawm lub thib peb thiab thib tsib carbons suab thaj (3S 'thiab 5').

Assembling polynucleotide - ib tug complex txheej txheem uas yuav siv sij hawm qhov chaw thaum lub enzyme DNA polymerase, uas muab tsuas cov saw hlau loj hlob ntawm ib kawg (3) nrog ib tug dawb hydroxy pab pawg neeg.

Tus qauv ntawm cov DNA molecule

Ib tug DNA molecule li zoo raws li lub protein yuav ua tau ib tug thawj, nrab thiab tertiary qauv.

Cov kab sab ntawm nucleotides nyob rau hauv lub DNA saw sij nws cov qauv. Secondary qauv yog tsim vim hydrogen bonds, lub hauv paus uas tshwm sim nteg complementarity hauv paus ntsiab lus. Nyob rau hauv lwm yam lus, nyob rau hauv lub synthesis ntawm cov DNA ob helix ua tej yam regularity: adenine, thymine raws li ib tug Circuit Court lwm yam, guanine - cytosine thiab vice versa. Officers ntawm adenine thiab thymine los yog guanine thiab cytosine yog tsim los ntawm ob tug nyob rau hauv tus thawj thiab nyob rau hauv lub caij nyoog kawg no cov ntaub ntawv peb hydrogen bonds. Xws li ib tug compound muab ib tug khoom daim ntawv cog lus nucleotide chains thiab sib npaug zos deb nruab nrab ntawm lawv.

Paub qhov sib lawv liag ntawm nucleotides nyob rau hauv ib tug DNA saw hlau los ntawm lub hauv paus ntsiab lus ntawm complementarity yuav raug ncua thib ob los yog ntxiv.

Lub tertiary qauv ntawm cov DNA complex yog tsim los ntawm peb-dimensional bonds, uas qauv ua rau nws compact thiab muaj peev xwm muab tso nyob rau hauv ib tug me me volume ntawm tes. Piv txwv li, E. coli DNA ntev yog ntau tshaj 1 hli, thaum lub cell ntev - ntawm tsawg tshaj li 5 microns.

Tus nab npawb ntawm nucleotides nyob rau hauv lub DNA, thiab nws yog lawv ntau kev sib raug zoo yog kev kawm mus rau hauv txoj cai Chergaffa (tus naj npawb ntawm purine bases yeej ib txwm sib npaug zos rau cov nqi ntawm pyrimidine). Qhov kev ncua deb ntawm nucleotides - ib qhov sib npaug zos rau 0,34 nm, thiab lawv molecular ceeb thawj.

Tus qauv ntawm ib tug RNA molecule

RNA yog sawv cev los ntawm ib tug polynucleotide saw, tsim los ntawm covalent bonds ntawm pentose (ribose nyob rau hauv cov ntaub ntawv no) thiab ib tug phosphate moiety. Nyob rau hauv ntev nws yog ntau luv DNA. Lub hom muaj pes tsawg leeg ntawm lub nitrogenous bases nyob rau hauv lub nucleotide thiab muaj cov sib txawv. Lub RNA pyrimidine puag thymine es tsis txhob ntawm uracil siv. Nyob ntawm seb lub zog ua nyob rau hauv lub cev, RNA tej zaum yuav peb hom.

• Ribosomal (rRNA) - feem ntau yuav muaj los ntawm 3,000 mus 5,000 nucleotides. Raws li ib tug tsim nyog yam ntxwv tivthaiv yog muab kev koom tes nyob rau hauv lub tsim ntawm lub active chaw ntawm ribosomes, qhov chaw uas yog ib lub tseem ceeb tshaj plaws dab nyob rau hauv lub cell - protein biosynthesis.
• Thauj (tRNA) - muaj ib tug nruab nrab ntawm 75 - 95 nucleotides, ua hloov lwm lub tsev mus rau qhov chaw ntawm yam amino acid polypeptide synthesis nyob rau hauv ribosome. Txhua yam ntawm tRNA (yam tsawg kawg 40) nws muaj nws txais tau tsuas rau nws ib tug sib lawv liag ntawm nucleotides los yog monomers.
• Cov ntaub ntawv (RNAi) - nyob rau hauv nucleotide muaj pes tsawg leeg yog heev ntau haiv neeg. Hloov ntawm kev tshuaj ntsuam genetic ntaub ntawv los ntawm DNA rau ribosomes, ua raws li ib tug qauv rau synthesis ntawm cov protein molecule.

Lub luag hauj lwm ntawm nucleotides nyob rau hauv lub cev

Nucleotides nyob rau hauv lub cell ua ib tug xov tooj ntawm ib qho tseem ceeb functions:

• yog siv raws li lub tsev blocks rau nucleic acids (nucleotide purine thiab pyrimidine series);
• muab kev koom tes nyob rau hauv ntau metabolic dab nyob rau hauv lub cell;
• yog ib feem ntawm lub ATP - lub ntsiab lub zog qhov chaw nyob rau hauv lub hlwb;
• ua raws li vectors ntawm kev txo kom muaj sib npaug nyob rau hauv lub cell (NAD +, NADP +, fad, FMN);
• ua raws li bioregulators;
• muaj peev xwm yuav tau ua ob txib extracellular kev synthesis (e.g., CAMP los yog cGMP).

Nucleotide - ib tug monomer unit uas ntaub ntawv ntau tebchaw - nucleic acids, tsis muaj uas cov kev hloov ntawm caj ces, nws cia thiab playback. Dawb nucleotides yog lub ntsiab Cheebtsam muab kev koom tes nyob rau hauv lub teeb liab zog dab thiab txhawb lub hlwb thiab tej hauj lwm ntawm tag nrho cov kab mob.