Kev sib cuam tshuam thiab cov qauv ntawm IRNA, tRNA, RRNA - peb lub ntsiab nucleic acids, suav nrog kev tshawb fawb xws li cytology. Nws yuav pab kom paub tias dab tsi yog lub luag haujlwm ntawm kev thauj ribonucleic acid (tRNA) hauv cov hlwb. Qhov no me me, tab sis tib lub sij hawm undeniably tseem ceeb molecule koom nyob rau hauv cov txheej txheem ntawm combining cov proteins uas ua rau lub cev.
Tus qauv ntawm tRNA yog dab tsi? Nws yog qhov nthuav heev los xav txog cov khoom no "los ntawm sab hauv", kom paub txog nws cov biochemistry thiab lub luag haujlwm lom neeg. Thiab tseem, tus qauv ntawm tRNA thiab nws lub luag haujlwm hauv cov protein synthesis cuam tshuam li cas?
TRNA yog dab tsi, nws ua haujlwm li cas?
Kev thauj ribonucleic acid yog koom nrog hauv kev tsim cov proteins tshiab. Yuav luag 10% ntawm tag nrho cov ribonucleic acids yog thauj. Txhawm rau kom paub meej tias cov tshuaj molecule yog tsim los ntawm dab tsi, peb yuav piav qhia txog cov qauv ntawm cov qauv thib ob ntawm tRNA. Cov qauv thib ob txiav txim siab tag nrho cov tshuaj lom neeg loj ntawm cov khoom.
Qhov no yog macromolecule uas muaj cov saw hlau polynucleotide. Nitrogenous hauv paus hauv nws txuas nrog hydrogen bonds. Raws li hauv DNA, RNA muaj 4 lub hauv paus nitrogenous: adenine,cytosine, guanine, thiab uracil. Hauv cov tebchaw no, adenine ib txwm cuam tshuam nrog uracil, thiab guanine, raws li ib txwm muaj, nrog cytosine.
Vim li cas cov nucleotide muaj cov npe ribo-? Tsuas yog, tag nrho cov linear polymers uas muaj ribose es tsis txhob ntawm pentose ntawm lub hauv paus ntawm nucleotide hu ua ribonucleic. Thiab hloov RNA yog ib qho ntawm 3 hom ntawm xws li ribonucleic polymer.
Structure of tRNA: biochemistry
Cia saib mus rau hauv cov txheej txheej tob tshaj plaws ntawm cov qauv molecular. Cov nucleotides no muaj 3 yam:
- Sucrose, ribose koom nrog txhua hom RNA.
- Phosphoric acid.
- Nitrogenous puag. Cov no yog purines thiab pyrimidines.
Nitrogenous hauv paus yog sib cuam tshuam los ntawm cov ntawv cog lus muaj zog. Nws yog kev cai los faib cov hauv paus rau hauv purine thiab pyrimidine.
Purines yog adenine thiab guanine. Adenine sib raug rau adenyl nucleotide ntawm 2 lub nplhaib sib txuas. Thiab guanine sib raug rau tib lub "ib lub nplhaib" guanine nucleotide.
YPyramidines yog cytosine thiab uracil. Pyrimidines muaj ib lub nplhaib qauv. Tsis muaj thymine hauv RNA, vim nws tau hloov los ntawm cov khoom xws li uracil. Qhov no yog qhov tseem ceeb kom nkag siab ua ntej saib lwm yam qauv ntawm tRNA.
Type of RNA
Raws li koj tuaj yeem pom, tus qauv ntawm TRNA tsis tuaj yeem piav qhia luv luv. Koj yuav tsum tau delve rau hauv biochemistry kom nkag siab lub hom phiaj ntawm cov molecule thiab nws cov qauv tseeb. Dab tsi lwm cov ribosomal nucleotides paub? Kuj tseem muaj cov matrix lossis cov ntaub ntawv thiab ribosomal nucleic acids. Abbreviated li RNA thiab RNA. Txhua tus 3molecules ua hauj lwm sib ze nrog ib leeg nyob rau hauv lub cell kom lub cev tau txais cov qauv protein globules kom raug.
Nws tsis tuaj yeem xav txog kev ua haujlwm ntawm ib lub polymer yam tsis muaj kev pab ntawm 2 lwm tus. Cov yam ntxwv ntawm tRNAs tau nkag siab ntau dua thaum pom nrog cov haujlwm uas cuam tshuam ncaj qha rau kev ua haujlwm ntawm ribosomes.
Cov qauv ntawm IRNA, tRNA, RRNA zoo ib yam li ntau txoj hauv kev. Txhua tus muaj lub hauv paus ribose. Txawm li cas los xij, lawv cov qauv thiab kev ua haujlwm txawv.
Kev Tshawb Fawb ntawm nucleic acids
Lub Swiss Johann Miescher pom macromolecules hauv cell nucleus hauv xyoo 1868, tom qab hu ua nucleins. Lub npe "nucleins" los ntawm lo lus (nucleus) - lub nucleus. Txawm hais tias me ntsis tom qab nws tau pom tias nyob rau hauv cov tsiaj txhu uas tsis muaj nucleus, cov tshuaj no kuj muaj. Nyob rau hauv nruab nrab ntawm lub xyoo pua 20th, Nobel nqi zog tau txais rau kev tshawb pom ntawm cov synthesis ntawm nucleic acids.
TRNA ua haujlwm hauv protein synthesis
Lub npe nws tus kheej - hloov RNA hais txog lub luag haujlwm tseem ceeb ntawm cov molecule. Qhov no nucleic acid "nqa" nrog nws qhov tseem ceeb amino acid xav tau los ntawm ribosomal RNA los ua ib qho protein.
Lub tRNA molecule muaj ob peb lub luag haujlwm. Qhov thib ib yog kev lees paub ntawm IRNA codon, qhov thib ob muaj nuj nqi yog kev xa cov tsev blocks - amino acids rau protein synthesis. Qee tus kws tshaj lij paub qhov txawv ntawm qhov lees paub ua haujlwm. Ntawd yog, qhov sib ntxiv ntawm cov amino acids raws li txoj cai covalent. Ib qho enzyme xws li aminocil-tRNA synthatase pab "txuas" cov amino acid no.
Tus qauv ntawm tRNA cuam tshuam li cas rau nwsua haujlwm? Qhov tshwj xeeb ribonucleic acid no yog teem nyob rau hauv xws li ib txoj kev uas ntawm ib sab ntawm nws muaj nitrogenous bases, uas yog ib txwm txuas nrog ua khub. Cov no yog cov ntsiab lus uas peb paub - A, U, C, G. Raws nraim 3 "cov ntawv" lossis nitrogenous hauv paus ua rau cov anticodon - cov txheej txheem rov qab uas cuam tshuam nrog codon raws li lub hauv paus ntsiab lus ntawm complementarity.
Qhov qauv tseem ceeb ntawm tRNA ua kom ntseeg tau tias yuav tsis muaj qhov yuam kev thaum txiav txim siab tus qauv nucleic acid. Tom qab tag nrho, nws nyob ntawm qhov tseeb ib ntus ntawm cov amino acids seb cov protein uas lub cev xav tau nyob rau lub sijhawm tam sim no yog tsim kom raug.
Lub tsev nta
Dab tsi yog cov yam ntxwv ntawm tRNA thiab nws txoj haujlwm lom neeg? Qhov no yog ib tug heev ancient qauv. Nws qhov loj me yog qhov chaw nyob ib puag ncig 73 - 93 nucleotides. Qhov hnyav molecular ntawm ib yam khoom yog 25,000–30,000.
Cov qauv ntawm cov qauv theem nrab ntawm tRNA tuaj yeem raug tshem tawm los ntawm kev kawm 5 lub ntsiab lus tseem ceeb ntawm cov molecule. Yog li, qhov no nucleic acid muaj cov hauv qab no:
- enzyme hu rau voj;
- xov rau kev sib cuag nrog ribosome;
- anticodon voj;
- txais qia;
- tus anticodon nws tus kheej.
Thiab kuj faib lub voj me me sib txawv hauv cov qauv thib ob. Ib lub xub pwg nyom hauv txhua hom tRNA yog tib yam - lub qia ntawm ob cytosine thiab ib qho adenosine residues. Nws yog nyob rau hauv qhov chaw no uas muaj kev sib txuas nrog 1 ntawm 20 muaj amino acids tshwm sim. Txhua amino acid muaj ib tug cais enzyme - nws tus kheej aminoacyl-tRNA.
Txhua cov ntaub ntawv uas encrypts tus qauv ntawm txhua tusnucleic acids muaj nyob hauv DNA nws tus kheej. Tus qauv ntawm tRNA nyob rau hauv tag nrho cov nyob creatures nyob rau hauv lub ntiaj teb no yuav luag zoo tib yam. Nws yuav zoo li nplooj thaum pom hauv 2-D.
Txawm li cas los xij, yog tias koj saib hauv ntim, cov molecule zoo li L-shaped geometric qauv. Qhov no suav hais tias yog tus qauv tertiary ntawm tRNA. Tab sis rau qhov yooj yim ntawm kev kawm nws yog ib txwm ua kom pom kev "untwist". Cov qauv tertiary yog tsim los ntawm kev sib cuam tshuam ntawm cov ntsiab lus ntawm cov qauv thib ob, cov seem uas sib koom ua ke.
Lub tRNA caj npab lossis lub nplhaib ua lub luag haujlwm tseem ceeb. Ib sab caj npab, piv txwv li, yuav tsum muaj kev sib txuas tshuaj nrog ib qho enzyme.
Ib tus yam ntxwv ntawm nucleotide yog qhov muaj ntau ntawm nucleosides. Muaj ntau dua 60 hom ntawm cov nucleosides me me no.
qauv ntawm tRNA thiab coding ntawm amino acids
Peb paub tias tRNA anticodon yog 3 molecules ntev. Txhua anticodon sib raug rau ib qho tshwj xeeb, "tus kheej" amino acid. Cov amino acid no txuas nrog tRNA molecule siv lub enzyme tshwj xeeb. Thaum cov 2 amino acids tuaj ua ke, cov ntawv cog lus rau tRNA tau tawg. Txhua cov tshuaj sib xyaw thiab cov enzymes xav tau kom txog rau thaum lub sijhawm xav tau. Qhov no yog li cas cov qauv thiab kev ua haujlwm ntawm tRNA sib cuam tshuam.
Muaj 61 hom ntawm cov molecules hauv cell. Nws tuaj yeem muaj 64 qhov sib txawv ntawm kev ua lej. Txawm li cas los xij, 3 hom tRNA ploj lawm vim qhov tseeb tias cov naj npawb ntawm cov nres codons hauv IRNA tsis muaj anticodons.
Kev sib cuam tshuam ntawm IRNA thiab TRNA
Cia peb xav txog kev sib cuam tshuam ntawm ib yam khoom nrog MRNA thiab RRNA, nrog rau cov yam ntxwv ntawm TRNA. Qauv thiab lub hom phiajmacromolecules yog interconnected.
Tus qauv ntawm IRNA luam cov ntaub ntawv los ntawm ib ntu ntawm DNA. DNA nws tus kheej yog qhov loj heev ntawm kev sib txuas ntawm cov molecules, thiab nws yeej tsis tawm hauv lub nucleus. Yog li ntawd, xav tau ib tus neeg nruab nrab RNA - xov xwm.
Raws li cov kab ke ntawm cov molecules theej los ntawm RNA, ribosome tsim cov protein. Lub ribosome yog cov qauv polynucleotide cais, cov qauv uas yuav tsum tau piav qhia.
Ribosomal tRNA kev sib cuam tshuam
Ribosomal RNA yog ib lub cev loj heev. Nws qhov hnyav molecular yog 1,000,000 - 1,500,000. Yuav luag 80% ntawm tag nrho RNA yog ribosomal nucleotides.
Nws zoo li ntes IRNA saw thiab tos cov tshuaj tiv thaiv uas yuav coj tRNA molecules nrog lawv. Ribosomal RNA muaj 2 subunits: me thiab loj.
Lub ribosome hu ua "lub Hoobkas", vim hais tias nyob rau hauv lub organelle no tag nrho cov synthesis ntawm cov khoom tsim nyog rau lub neej txhua hnub tshwm sim. Nws kuj yog ib lub cell qauv qub heev.
Yuav ua li cas protein synthesis tshwm sim hauv ribosome?
Cov qauv ntawm tRNA thiab nws lub luag haujlwm hauv cov protein synthesis yog sib cuam tshuam. Lub anticodon nyob rau ntawm ib sab ntawm ribonucleic acid yog tsim nyob rau hauv nws daim ntawv rau lub luag hauj lwm tseem ceeb - xa cov amino acids mus rau lub ribosome, qhov chaw uas maj mam sib haum xeeb ntawm cov protein tshwm sim. Qhov tseem ceeb, TRNA ua tus neeg nruab nrab. Nws txoj haujlwm tsuas yog nqa cov amino acid tsim nyog xwb.
Thaum cov ntaub ntawv raug nyeem los ntawm ib feem ntawm IRNA, ribosome txav mus ntxiv raws cov saw hlau. Lub matrix tsuas yog xav tau rau kev sib kisencoded cov ntaub ntawv hais txog kev teeb tsa thiab kev ua haujlwm ntawm ib qho protein. Tom ntej no, lwm tRNA mus txog lub ribosome nrog nws cov nitrogenous bases. Nws kuj txiav txim siab qhov txuas ntxiv ntawm RNC.
Kev txiav txim siab tshwm sim raws li hauv qab no. Nitrogenous bases ua ke raws li lub hauv paus ntsiab lus ntawm complementarity tib yam li hauv DNA nws tus kheej. Raws li, TRNA pom qhov twg nws xav tau "moor" thiab qhov twg "hangar" xa cov amino acid.
Tom qab ntawd nyob rau hauv ribosome, cov amino acids xaiv nyob rau hauv txoj kev no yog chemically khi, ib kauj ruam los ntawm kauj ruam ib tug tshiab linear macromolecule yog tsim, uas, tom qab kawg ntawm synthesis, twists mus rau hauv lub globule (pob). Siv tRNAs thiab IRNAs, tau ua tiav lawv txoj haujlwm, raug tshem tawm ntawm cov protein "lub Hoobkas".
Thaum thawj ntu ntawm codon txuas mus rau anticodon, cov ntawv nyeem tau txiav txim siab. Tom qab ntawd, yog tias vim li cas ib qho kev hloov pauv tshwm sim, ces qee qhov kos npe ntawm cov protein yuav raug tsis lees paub. Lub ribosome tsis tuaj yeem cuam tshuam rau hauv cov txheej txheem no thiab daws qhov teeb meem. Tsuas yog tom qab ua tiav cov txheej txheem, 2 rRNA subunits tau ua ke dua. Qhov nruab nrab, rau txhua 10 4amino acids, muaj 1 yuam kev. Rau txhua 25 cov proteins uas twb tau sib sau ua ke, tsawg kawg yog 1 qhov yuam kev rov ua dua yog qhov tseeb.
TRNA as relic molecules
Vim tias tRNA tuaj yeem muaj nyob rau lub sijhawm ntawm lub hauv paus chiv keeb ntawm lub neej hauv ntiaj teb, nws yog hu ua relic molecule. Nws ntseeg tau tias RNA yog thawj tus qauv uas muaj nyob ua ntej DNA thiab tom qab ntawd hloov zuj zus. RNA World Hypothesis - tsim nyob rau hauv 1986 los ntawm laureate W alter Gilbert. Txawm li cas los xij, los ua pov thawjnws tseem nyuaj. Txoj kev xav tau tiv thaiv los ntawm qhov tseeb tseeb - tRNA molecules tuaj yeem khaws cov ntaub ntawv thaiv thiab siv cov ntaub ntawv no, uas yog, ua haujlwm.
Tab sis cov neeg tawm tsam ntawm txoj kev xav tau sib cav tias lub neej luv luv ntawm cov khoom tsis tuaj yeem lav tias tRNA yog cov khoom thauj zoo ntawm cov ntaub ntawv lom neeg. Cov nucleotides no yog degraded sai heev. Lub neej ntawm tRNA nyob rau hauv tib neeg lub hlwb nyob ntawm ob peb feeb mus rau ob peb teev. Qee hom tuaj yeem kav ntev txog ib hnub. Thiab yog hais tias peb tham txog tib nucleotides nyob rau hauv cov kab mob, ces cov ntsiab lus yog luv luv - mus txog rau ob peb teev. Tsis tas li ntawd, cov qauv thiab kev ua haujlwm ntawm tRNA yog qhov nyuaj heev rau lub molecule los ua lub hauv paus tseem ceeb ntawm lub ntiaj teb biosphere.
