Protein yog lub hauv paus ntawm lub cell thiab lub cev lub neej. Ua haujlwm ntau hauv cov ntaub so ntswg nyob, nws siv nws lub peev xwm tseem ceeb: kev loj hlob, kev ua haujlwm tseem ceeb, txav mus los thiab kev yug me nyuam. Nyob rau hauv cov ntaub ntawv no, lub cell nws tus kheej synthesizes ib tug protein, lub monomer ntawm uas yog ib tug amino acid. Nws txoj hauj lwm nyob rau hauv lub hauv paus qauv ntawm cov protein yog programmed los ntawm cov noob caj noob ces code, uas yog inherited. Txawm tias kev hloov pauv ntawm cov noob los ntawm niam lub cell mus rau tus ntxhais cell tsuas yog ib qho piv txwv ntawm kev hloov cov ntaub ntawv hais txog cov qauv ntawm cov protein. Qhov no ua rau nws lub cev molecule uas yog lub hauv paus ntawm lub neej lom neeg.
tus yam ntxwv ntawm cov qauv protein
Protein molecules synthesized in a cell is biological polymers.
Nyob hauv cov protein, cov monomer yeej ib txwm yog cov amino acid, thiab lawv cov kev sib xyaw ua ke ua cov saw hlau tseem ceeb ntawm cov molecule. Nws yog hu ua lub hauv paus qauv ntawm ib tug protein molecule, uas tom qab spontaneously los yog nyob rau hauv qhov kev txiav txim ntawm lom catalysts yog hloov mus rau ib tug thib ob, tertiary los yog domain qauv.
Secondary and tertiary structure
Cov protein ntauqauv yog kev hloov kho spatial ntawm cov saw tseem ceeb cuam tshuam nrog kev tsim cov hydrogen bonds hauv cheeb tsam polar. Vim li no, cov saw hlau yog folded rau hauv loops los yog twisted mus rau hauv ib tug kauv, uas yuav siv sij hawm tsawg chaw. Thaum lub sij hawm no, lub zos nqi ntawm cov seem ntawm cov molecule hloov, uas ua rau tsim ib tug tertiary qauv - ib tug globular. Cov seem crimped los yog helical yog twisted rau hauv cov pob nrog kev pab los ntawm disulfide bonds.
Cov pob lawv tus kheej tso cai rau koj los tsim cov qauv tshwj xeeb uas xav tau los ua cov haujlwm ua haujlwm. Nws yog ib qho tseem ceeb tias txawm tias tom qab kev hloov kho, monomer ntawm cov protein yog cov amino acid. Qhov no kuj tau lees paub tias thaum lub sij hawm tsim cov theem nrab, thiab tom qab ntawd cov qauv tertiary thiab quaternary ntawm cov protein, cov amino acid thawj theem tsis hloov.
Tus yam ntxwv ntawm cov protein monomers
Y Txhua cov proteins yog polymers, cov monomers uas yog amino acids. Cov no yog cov organic tebchaw uas yog synthesized los ntawm ib tug nyob cell los yog nkag mus rau nws raws li cov as-ham. Ntawm cov no, ib qho protein molecule yog synthesized ntawm ribosomes siv tus xa xov RNA matrix nrog kev siv nyiaj ntau ntawm lub zog. Amino acids lawv tus kheej yog cov tebchaw nrog ob pawg tshuaj nquag: carboxyl radical thiab ib pawg amino nyob ntawm alpha carbon atom. Nws yog cov qauv no uas tso cai rau cov molecule hu ua alpha-amino acid uas muaj peev xwm tsim peptide bonds. Protein monomers tsuas yog alpha-amino acids xwb.
Peptide daim ntawv cog lus
Peptide daim ntawv cog lus yog ib pawg tshuaj molecular tsim los ntawm carbon, oxygen, hydrogen thiab nitrogen atoms. Nws yog tsim nyob rau hauv tus txheej txheem ntawm splitting tawm dej los ntawm cov carboxyl pawg ntawm ib alpha-amino acid thiab cov amino pawg ntawm lwm. Hauv qhov no, hydroxyl radical raug cais tawm ntawm carboxyl radical, uas, sib txuas nrog cov proton ntawm pawg amino, tsim dej. Yog li ntawd, ob lub amino acids txuas nrog covalent polar bond CONH.
Tsuas yog alpha-amino acids, monomers ntawm cov proteins ntawm cov kab mob muaj sia, tuaj yeem tsim nws. Nws yog ib qho ua tau los soj ntsuam qhov tsim ntawm peptide daim ntawv cog lus hauv chav kuaj, txawm hais tias nws yog ib qho nyuaj rau xaiv cov khoom me me hauv kev daws teeb meem. Protein monomers yog cov amino acids, thiab nws cov qauv yog programmed los ntawm genetic code. Yog li ntawd, cov amino acids yuav tsum tau txuas rau hauv ib qho kev txiav txim nruj. Qhov no yog tsis yooj yim sua nyob rau hauv ib qho kev daws nyob rau hauv chaotic equilibrium tej yam kev mob, thiab yog li ntawd nws yog tseem tsis yooj yim sua kom synthesize ib complex protein artificially. Yog tias muaj cov khoom siv uas tso cai rau kev txiav txim siab nruj ntawm kev sib dhos ntawm cov molecule, nws cov kev saib xyuas yuav kim heev.
Protein synthesis nyob rau hauv lub cell
Nyob hauv lub cell uas muaj sia nyob, qhov xwm txheej yog thim rov qab, vim nws muaj cov cuab yeej biosynthesis tsim. Ntawm no, cov monomers ntawm cov protein molecules tuaj yeem sib sau ua ke rau hauv cov molecules hauv kev nruj nruj. Nws yog programmed los ntawm genetic code khaws cia hauv chromosomes. Yog tias nws tsim nyog los ua ke cov txheej txheem protein lossis enzyme, cov txheej txheem ntawm kev nyeem DNA code thiab tsim cov matrix (thiabRNA) los ntawm cov protein uas yog synthesized. Cov monomer yuav maj mam koom nrog cov saw polypeptide loj hlob ntawm lub ribosomal apparatus. Thaum ua tiav cov txheej txheem no, cov saw hlau ntawm cov amino acid residues yuav raug tsim, uas spontaneously los yog thaum lub sij hawm enzymatic txheej txheem yuav tsim ib tug thib ob, tertiary los yog domain qauv.
Y
Regularities of biosynthesis
Qee yam ntawm cov protein biosynthesis, kis ntawm cov ntaub ntawv keeb kwm thiab nws qhov kev siv yuav tsum tau qhia. Lawv dag nyob rau hauv qhov tseeb hais tias DNA thiab RNA yog homogeneous tshuaj muaj xws li monomers. Namely, DNA yog tsim los ntawm nucleotides, ib yam li RNA. Cov yav tas yog nthuav tawm nyob rau hauv daim ntawv ntawm cov ntaub ntawv, thauj thiab ribosomal RNA. Qhov no txhais tau hais tias tag nrho cov cuab yeej ntawm tes ua lub luag haujlwm rau khaws cov ntaub ntawv keeb kwm thiab cov protein biosynthesis yog ib qho tag nrho. Yog li ntawd, lub cell nucleus nrog ribosomes, uas kuj yog sau RNA molecules, yuav tsum tau muab xam raws li ib tug tag nrho apparatus rau khaws cia cov noob thiab lawv siv.
Qhov thib ob feature ntawm biosynthesis ntawm cov protein, lub monomer ntawm uas yog alpha-amino acid, yog txiav txim siab nruj txiav txim ntawm lawv txuas. Txhua tus amino acid yuav tsum coj nws qhov chaw nyob rau hauv thawj cov qauv protein. Qhov no tau lees paub los ntawm cov cuab yeej tau piav qhia saum toj no rau kev khaws cia thiab siv cov ntaub ntawv keeb kwm yav dhau los. Kev ua yuam kev tuaj yeem tshwm sim hauv nws, tab sis lawv yuav raug tshem tawm los ntawm nws. Nyob rau hauv rooj plaub ntawm kev sib dhos tsis raug, cov molecule yuav raug rhuav tshem, thiab biosynthesis yuav pib dua.
