Protein synthesis yog txheej txheem tseem ceeb heev. Nws yog tus uas pab peb lub cev loj hlob thiab loj hlob. Nws koom nrog ntau cov qauv ntawm tes. Tom qab tag nrho, ua ntej koj yuav tsum to taub dab tsi raws nraim peb yuav synthesize.
Yuav ua li cas cov protein yuav tsum tau tsim nyob rau tam sim no - enzymes yog lub luag haujlwm rau qhov no. Lawv tau txais cov cim qhia los ntawm lub xov tooj ntawm tes hais txog qhov xav tau ntawm cov protein tshwj xeeb, tom qab ntawd nws cov synthesis pib.
Qhov twg protein synthesis tshwm sim
Nyob hauv ib lub xovtooj ntawm tes, qhov chaw tseem ceeb ntawm cov protein biosynthesis yog ribosome. Nws yog ib tug loj macromolecule nrog ib tug complex asymmetric qauv. Nws muaj RNA (ribonucleic acids) thiab cov proteins. Ribosomes tuaj yeem nyob ib leeg. Tab sis feem ntau lawv tau ua ke nrog EPS, uas pab txhawb kev sib cais thiab thauj cov protein.
Yog ribosomes zaum ntawm endoplasmic reticulum, nws yog hu ua ntxhib ER. Thaum kev txhais lus khaus, ob peb ribosomes tuaj yeem txav mus raws ib qho qauv ib zaug. Lawv ua raws ib leeg thiab tsis cuam tshuam nrog lwm cov organelles.
Yuav tsum tau ua dab tsi rau kev sib txuassquirrel
Rau cov txheej txheem mus txuas ntxiv, nws yog ib qho tsim nyog kom tag nrho cov khoom tseem ceeb ntawm cov protein synthesis nyob rau hauv qhov chaw:
- Ib qho kev pab cuam uas teev qhov kev txiav txim ntawm cov amino acid residues nyob rau hauv cov saw, uas yog mRNA, uas yuav hloov cov ntaub ntawv no los ntawm DNA mus rau ribosomes.
- Amino acid cov khoom siv los ntawm qhov tshiab molecule yuav tsim.
- tRNA, uas yuav xa txhua cov amino acid rau ribosome, yuav koom nrog hauv kev txiav txim siab ntawm caj ces.
- Aminoacyl-tRNA synthetase.
- Ribosome yog qhov chaw tseem ceeb ntawm cov protein biosynthesis.
- Zoo.
- Protein yam (txhua theem muaj nws tus kheej).
YMagnesium ions.
Tam sim no cia peb saib ntawm lawv txhua tus kom ntxaws ntxiv thiab nrhiav seb cov proteins tsim li cas. Cov txheej txheem ntawm biosynthesis yog qhov nthuav heev, txhua yam khoom siv ua haujlwm tsis sib xws.
Synthesis program, matrix search
Txhua cov ntaub ntawv hais txog cov proteins uas peb lub cev tuaj yeem tsim muaj nyob hauv DNA. Deoxyribonucleic acid yog siv los khaws cov ntaub ntawv ntawm caj ces. Nws yog ruaj khov nyob rau hauv cov chromosomes thiab nyob rau hauv lub cell nyob rau hauv lub nucleus (yog hais tias peb tham txog eukaryotes) los yog floats nyob rau hauv lub cytoplasm (hauv prokaryotes).
Tom qab DNA tshawb fawb thiab lees paub txog nws txoj haujlwm caj ces, nws tau pom tseeb tias nws tsis yog tus qauv ncaj qha rau kev txhais lus. Kev soj ntsuam tau coj mus rau cov lus qhia tias RNA cuam tshuam nrog cov protein synthesis. Cov kws tshawb fawb tau txiav txim siab tias nws yuav tsum yog tus neeg nruab nrab, hloov cov ntaub ntawv los ntawm DNA mus rau ribosomes, ua haujlwm raws li matrix.
Tam sim no muajribosomes qhib, lawv RNA ua rau feem coob ntawm cellular ribonucleic acid. Txhawm rau xyuas seb nws puas yog ib qho matrix rau kev sib txuas ntawm cov protein, A. N. Belozersky thiab A. S. Spirin hauv 1956-1957. ua qhov kev soj ntsuam sib piv ntawm cov muaj pes tsawg leeg ntawm nucleic acids hauv ntau cov kab mob.
Nws tau xav tias yog tias lub tswv yim ntawm "DNA-rRNA-protein" yog qhov tseeb, ces qhov sib xyaw ntawm tag nrho RNA yuav hloov pauv raws li DNA. Tab sis, txawm hais tias qhov sib txawv loj ntawm deoxyribonucleic acid nyob rau hauv ntau hom, muaj pes tsawg leeg ntawm tag nrho cov ribonucleic acid yog zoo sib xws nyob rau hauv tag nrho cov kab mob. Los ntawm qhov no, cov kws tshawb fawb tau xaus lus tias lub ntsiab cellular RNA (uas yog, ribosomal) tsis yog ib qho nruab nrab ntawm cov neeg nqa khoom ntawm cov ntaub ntawv caj ces thiab cov protein.
Discovery of mRNA
Tom qab nws tau tshawb pom tias ib feem me me ntawm RNA rov ua cov txheej txheem ntawm DNA thiab tuaj yeem ua tus neeg nruab nrab. Xyoo 1956, E. Volkin thiab F. Astrachan tau kawm txog cov txheej txheem ntawm RNA synthesis hauv cov kab mob uas kis tus kab mob T2 bacteriophage. Tom qab nws nkag mus rau hauv lub cell, nws hloov mus rau synthesis ntawm phage proteins. Nyob rau tib lub sijhawm, qhov tseem ceeb ntawm RNA tsis hloov. Tab sis nyob rau hauv lub cell, lub synthesis ntawm ib tug me me feem ntawm metabolically unstable RNA pib, lub nucleotide ib theem zuj zus uas zoo ib yam li cov muaj pes tsawg leeg ntawm phage DNA.
Xyoo 1961, qhov me me ntawm ribonucleic acid raug cais tawm ntawm tag nrho cov huab hwm coj ntawm RNA. Cov ntaub ntawv pov thawj ntawm nws txoj haujlwm kho kom haum xeeb tau muab los ntawm kev sim. Tom qab kis kab mob ntawm cov hlwb nrog T4 phage, mRNA tshiab tau tsim. Nws txuas nrog cov qub mastersribosomes (tsis muaj ribosomes tshiab pom tom qab kis kab mob), uas tau pib tsim cov phage proteins. Qhov no "DNA-zoo li RNA" tau pom los ua ntxiv rau ib qho ntawm phage's DNA strands.
Hauv xyoo 1961, F. Jacob thiab J. Monod tau hais tias qhov RNA no nqa cov ntaub ntawv los ntawm cov noob mus rau ribosomes thiab yog cov matrix rau kev sib txuas ntawm cov amino acids thaum lub sij hawm tsim cov protein.
Kev xa cov ntaub ntawv mus rau qhov chaw ntawm cov protein synthesis yog ua los ntawm mRNA. Cov txheej txheem ntawm kev nyeem cov ntaub ntawv los ntawm DNA thiab tsim cov tub txib RNA hu ua transcription. Tom qab nws, RNA tau txais kev hloov pauv ntxiv, qhov no yog hu ua "kev ua haujlwm". Hauv chav kawm ntawm nws, qee ntu tuaj yeem txiav tawm ntawm matrix ribonucleic acid. Tom qab ntawd mRNA mus rau ribosomes.
tsim khoom rau cov proteins: amino acids
Muaj 20 amino acids nyob rau hauv tag nrho, qee qhov ntawm lawv yog qhov tseem ceeb, uas yog, lub cev tsis tuaj yeem tsim lawv. Yog tias qee cov kua qaub hauv lub cell tsis txaus, qhov no tuaj yeem ua rau qeeb qeeb hauv kev txhais lus lossis txawm tias ua tiav ntawm cov txheej txheem. Lub xub ntiag ntawm txhua amino acid nyob rau hauv kom muaj nuj nqis yog lub ntsiab yuav tsum tau rau cov protein biosynthesis mus kom raug.
Cov kws tshawb fawb tau txais cov ntaub ntawv dav dav txog cov amino acids rov qab rau xyoo 19th. Tom qab ntawd, xyoo 1820, thawj ob amino acids, glycine thiab leucine, raug cais tawm.
Cov kab ke ntawm cov monomers hauv cov protein (lub npe hu ua thawj qauv) ua tiav txiav txim siab nws cov koom haum tom ntej, thiab yog li nws lub cev thiab tshuaj lom neeg.
Kev thauj cov amino acids: tRNA thiab aa-tRNA synthetase
Tab sis cov amino acids tsis tuaj yeem tsim lawv tus kheej rau hauv cov saw hlau protein. Txhawm rau kom lawv mus rau qhov chaw tseem ceeb ntawm cov protein biosynthesis, hloov RNA yog xav tau.
Txhua aa-tRNA synthetase paub tsuas yog nws tus kheej cov amino acid thiab tsuas yog tRNA uas nws yuav tsum tau txuas. Nws hloov tawm tias tsev neeg ntawm cov enzymes no suav nrog 20 ntau yam ntawm synthetases. Nws tsuas yog tseem hais tias cov amino acids txuas nrog tRNA, ntau qhov tseeb, rau nws tus neeg txais hydroxyl "tail". Txhua cov kua qaub yuav tsum muaj nws tus kheej hloov RNA. Qhov no yog saib xyuas los ntawm aminoacyl-tRNA synthetase. Nws tsis tsuas yog phim cov amino acids rau kev thauj mus los kom raug, nws kuj tswj cov tshuaj tiv thaiv ester bonding.
Tom qab ua tiav cov tshuaj tiv thaiv kev sib txuas, tRNA mus rau qhov chaw ntawm cov protein synthesis. Qhov no xaus cov txheej txheem npaj thiab kev tshaj tawm pib. Xav txog cov kauj ruam tseem ceeb hauv cov protein biosynthesis :
- pib;
- elongation;
- kev txiav txim.
Synthesis cov kauj ruam: pib
Yuav ua li cas protein biosynthesis thiab nws cov kev cai coj qhov chaw? Cov kws tshawb fawb tau sim los txiav txim qhov no rau lub sijhawm ntev. Ntau qhov kev xav tau muab tso rau pem hauv ntej, tab sis cov cuab yeej siv niaj hnub no tau dhau los ua, peb pib nkag siab zoo dua cov ntsiab lus ntawm kev tshaj tawm.
Lub ribosome, qhov chaw tseem ceeb ntawm cov protein biosynthesis, pib nyeem mRNA los ntawm qhov chaw uas nws feem encoding cov saw polypeptide pib. Lub ntsiab lus no yog nyob ntawm ib qhodeb ntawm qhov pib ntawm tus tub txib RNA. Lub ribosome yuav tsum paub lub ntsiab lus ntawm mRNA los ntawm kev nyeem ntawv pib thiab txuas mus rau nws.
Initiation - ib txheej txheej xwm uas muab qhov pib tshaj tawm. Nws suav nrog cov proteins (cov txheej txheem pib), tus pib tRNA thiab tus pib tshwj xeeb codon. Nyob rau theem no, lub subunit me me ntawm ribosome khi rau kev pib cov proteins. Lawv tiv thaiv nws los ntawm kev tiv tauj lub subunit loj. Tab sis lawv tso cai rau koj txuas nrog tus pib tRNA thiab GTP.
Tom qab ntawd qhov nyuaj no "tso" ntawm mRNA, raws nraim ntawm qhov chaw uas tau lees paub los ntawm ib qho ntawm qhov pib. Yuav tsis muaj qhov yuam kev, thiab ribosome pib nws txoj kev mus los ntawm tus tub txib RNA, nyeem nws cov codons.
Thaum lub complex ncav cuag qhov pib codon (AUG), lub subunit nres txav thiab, nrog kev pab los ntawm lwm yam protein yam, khi rau lub loj subunit ntawm lub ribosome.
Synthesis cov kauj ruam: elongation
Nyeem mRNA cuam tshuam nrog kev sib txuas ntawm cov saw hlau protein los ntawm polypeptide. Nws pib los ntawm kev ntxiv ib qho amino acid residue tom qab lwm tus rau lub molecule hauv kev tsim kho.
Txhua cov amino acid residue tshiab tau ntxiv rau carboxyl kawg ntawm peptide, C-terminus loj hlob.
Synthesis cov kauj ruam: termination
Thaum lub ribosome mus txog qhov txiav tawm codon ntawm tus xa xov RNA, kev sib txuas ntawm cov saw hlau polypeptide nres. Hauv nws lub xub ntiag, lub cev tsis tuaj yeem lees txais ib qho tRNA. Hloov chaw, qhov kev txiav tawm tuaj rau hauv kev ua si. Lawv tso cov protein ua tiav los ntawm cov ribosome nres.
Tom qabTom qab kev txhais lus raug txiav lawm, lub ribosome tuaj yeem tawm ntawm mRNA los yog txuas ntxiv mus txuas ntxiv yam tsis tau txhais.
Lub rooj sib tham ntawm ribosome nrog kev pib tshiab codon (ntawm tib txoj hlua thaum lub sijhawm txuas ntxiv ntawm kev txav lossis ntawm mRNA tshiab) yuav ua rau kev pib tshiab.
Tom qab cov molecule tiav lawm tawm ntawm qhov chaw tseem ceeb ntawm cov protein biosynthesis, nws tau sau npe thiab xa mus rau nws qhov chaw. Dab tsi ua haujlwm nws yuav ua yog nyob ntawm nws cov qauv.
txheej txheem tswj
Nyob ntawm lawv qhov kev xav tau, lub xov tooj ntawm tes yuav tswj hwm kev tshaj tawm. Kev tswj hwm ntawm cov protein biosynthesis yog ib txoj haujlwm tseem ceeb heev. Nws tuaj yeem ua tau ntau txoj hauv kev.
Yog tias lub xovtooj ntawm tes tsis xav tau qee yam sib xyaw, nws yuav nres RNA biosynthesis - protein biosynthesis tseem yuav nres. Tom qab tag nrho, tsis muaj matrix, tag nrho cov txheej txheem yuav tsis pib. Thiab qub mRNAs sai sai.
Muaj lwm txoj cai ntawm cov protein biosynthesis: lub cell tsim cov enzymes uas cuam tshuam rau theem pib. Lawv cuam tshuam nrog kev txhais lus, txawm tias muaj kev nyeem ntawv matrix.
Txoj kev thib ob yog qhov tsim nyog thaum kev tsim cov protein ntau yuav tsum tau muab tua tam sim no. Thawj txoj hauv kev suav nrog kev txuas ntxiv ntawm kev txhais lus qeeb rau qee lub sijhawm tom qab kev tso tseg ntawm mRNA synthesis.
Ib lub xovtooj yog ib txoj hauv kev uas txhua yam khaws cia hauv qhov sib npaug thiab ua haujlwm meej ntawm txhua lub molecule. Nws yog ib qho tseem ceeb kom paub cov hauv paus ntsiab lus ntawm txhua txoj kev tshwm sim hauv lub cell. Yog li peb tuaj yeem nkag siab zoo dua qhov tshwm sim hauv cov ntaub so ntswg thiab hauv lub cev tag nrho.
