Cov txheej txheem ntawm cov protein biosynthesis tseem ceeb heev rau lub cell. Txij li cov proteins yog cov tshuaj complex uas ua lub luag haujlwm tseem ceeb hauv cov ntaub so ntswg, lawv yog qhov tseem ceeb. Vim li no, tag nrho cov saw ntawm cov txheej txheem biosynthesis yog pom nyob rau hauv lub cell, uas tshwm sim nyob rau hauv ob peb organelles. Qhov no lav qhov kev tsim tawm ntawm tes thiab muaj peev xwm muaj nyob.
Lub ntsiab ntawm cov txheej txheem ntawm cov protein biosynthesis
Tsuas yog qhov chaw rau kev tsim cov protein ntau yog qhov ntxhib endoplasmic reticulum. Ntawm no yog nyob rau hauv feem ntau ntawm cov ribosomes, uas yog lub luag hauj lwm rau kev tsim ntawm polypeptide saw. Txawm li cas los xij, ua ntej lub sijhawm txhais lus (cov txheej txheem ntawm cov protein synthesis) pib, ua kom cov noob, uas khaws cov ntaub ntawv hais txog cov qauv protein, yuav tsum tau ua. Tom qab ntawd, yuav tsum luam cov ntu ntawm DNA (los yog RNA, yog tias cov kab mob biosynthesis raug txiav txim siab) yuav tsum tau.
Tom qab luam DNA, cov txheej txheem ntawm kev tsim tus xa xov RNA yog xav tau. Raws li nws, cov synthesis ntawm cov saw protein yuav ua tau. Ntxiv mus, tag nrho cov theem uas tshwm sim nrog kev koom tes ntawm nucleic acids yuav tsum tshwm sim nyob rau hauv lub cell nucleus. Txawm li cas los xij, qhov no tsis yog qhov kev sib txuas ntawm cov protein. Qhov no yogqhov chaw uas npaj rau biosynthesis tau ua.
YRibosomal protein biosynthesis
Qhov chaw tseem ceeb uas cov protein synthesis tshwm sim yog ribosome, cell organelle muaj ob lub subunits. Muaj ntau tus qauv zoo li no hauv lub xovtooj ntawm tes, thiab lawv feem ntau nyob ntawm daim nyias nyias ntawm cov tawv nqaij endoplasmic reticulum. Lub biosynthesis nws tus kheej tshwm sim raws li hauv qab no: tus tub txib RNA tsim nyob rau hauv lub cell nucleus tawm los ntawm lub nuclear pores mus rau hauv lub cytoplasm thiab ntsib nrog cov ribosome. Tom qab ntawd cov mRNA raug thawb mus rau hauv qhov sib txawv ntawm cov subunits ntawm ribosome, tom qab uas thawj cov amino acid yog tsau.
Rau qhov chaw uas muaj protein synthesis tshwm sim, amino acids tau muab nrog kev pab los ntawm RNA. Ib qho piv txwv zoo li no tuaj yeem nqa ib qho amino acid ib zaug. Lawv koom nyob rau hauv lem, nyob ntawm seb codon ib theem zuj zus ntawm tub txib RNA. Tsis tas li ntawd, kev sib xyaw ua ke yuav nres ib ntus.
Thaum tsiv raws mRNA, cov ribosome tuaj yeem nkag mus rau thaj chaw (introns) uas tsis yog code rau cov amino acids. Hauv cov chaw no, cov ribosome tsuas yog txav raws mRNA, tab sis tsis muaj cov amino acids ntxiv rau cov saw hlau. Thaum lub ribosome ncav cuag lub exon, uas yog, qhov chaw uas code rau cov kua qaub, ces nws reattaches mus rau lub polypeptide.
Postsynthetic hloov kho ntawm cov proteins
Tom qab ribosome mus txog qhov nres codon ntawm tus xa xov RNA, cov txheej txheem ntawm kev sib txuas ncaj qha tiav. Txawm li cas los xij, cov txiaj ntsig molecule muaj cov qauv tseem ceeb thiab tseem tsis tuaj yeem ua cov haujlwm tshwj xeeb rau nws. Txhawm rau kom ua haujlwm tau zoo, moleculeyuav tsum tau npaj rau hauv ib qho qauv: theem nrab, tertiary lossis ntau dua - quaternary.
Lub koom haum ntawm cov protein
Cov qauv theem nrab - thawj theem ntawm lub koom haum tsim qauv. Yuav kom ua tiav nws, thawj cov saw hlau polypeptide yuav tsum coil (daim ntawv alpha helices) lossis quav (tsim beta txheej). Tom qab ntawd, txhawm rau txhawm rau siv qhov chaw tsawg dua raws qhov ntev, cov molecule tau cog lus ntau dua thiab coiled rau hauv lub pob vim yog hydrogen, covalent thiab ionic bonds, nrog rau kev sib cuam tshuam ntawm kev sib tshuam. Yog li, cov qauv globular ntawm cov protein tau txais.
Quadternary protein qauv
Cov qauv quaternary yog qhov nyuaj tshaj plaws ntawm txhua tus. Nws muaj ob peb ntu nrog cov qauv globular, txuas nrog fibrillar filaments ntawm polypeptide. Tsis tas li ntawd, cov qauv tertiary thiab quaternary tuaj yeem muaj cov carbohydrate lossis lipid residue, uas nthuav cov spectrum ntawm cov protein ua haujlwm. Hauv particular, glycoproteins, complex compounds ntawm cov protein thiab carbohydrate, yog immunoglobulins thiab ua haujlwm tiv thaiv. Tsis tas li ntawd, glycoproteins nyob ntawm cov cell membranes thiab ua haujlwm ua receptors. Txawm li cas los xij, cov molecule tau hloov pauv tsis yog qhov twg cov protein synthesis tshwm sim, tab sis nyob rau hauv lub du endoplasmic reticulum. Ntawm no muaj qhov ua tau ntawm kev txuas lipids, hlau thiab carbohydrates rau cov protein ntau.
