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Download The job of this mRNA is to carry the gene`s message from the DNA
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ThejobofthismRNAistocarrythegene’smessagefromtheDNAoutofthenucleustoa ribosomeforproductionofaparticularproteinthatthisgenecodesfor.Therecanbeseveral millionribosomesinatypicaleukaryoticcell.ThesecomplexcatalyticmachinesusethemRNA copyofthegeneticinformationtoassembleaminoacidbuildingblocksintothethree dimensionalproteinsthatareessentialforlife.Let'sseehowitworks.Theribosomeis composedofonelargeandonesmallsubunitthatassemblearoundthemessengerRNA,which thenpassesthroughtheribosomelikeacomputertape.Theaminoacidbuildingblocks(that's thesmallglowingredmolecules)arecarriedintotheribosomeattachedtospecifictransfer RNA's(that'sthelargergreenmoleculesalsoreferredtoastRNA).Thesmallsubunitofthe ribosomepositionsthemRNAsothatitcanbereadingroupsof3lettersknownasacodon. EachcodononthemRNAmatchesacorrespondinganticodononthebaseofatransferRNA molecule.Thelargersubunitoftheribosomeremoveseachaminoacidandjoinsitontothe growingproteinchain.AsthemRNAisratchetedthroughtheribosomethemRNAsequenceis translatedintoanaminoacidsequence.Therearethreelocationsinsidetheribosome designatedtheAsite,thePsite,andtheEsite.Theadditionofeachaminoacidisa3step cycle.First,thetRNAenterstheribosomeattheAsiteandistestedforcodon-anticodonmatch withthemRNA.Next,providedthereisacorrectmatch,thetRNAisshiftedtothePsiteand theaminoaciditcarriesisaddedtotheendoftheaminoacidchain.ThemRNAisalso ratchetedon3nucleotides,or1codon.Thirdly,thespenttRNAismovedtotheEsiteandthen ejectedfromtheribosometoberecycled.Astheproteinsynthesisproceedsthefinishedchain emergesfromtheribosome.Itfoldsupintoapreciseshapedeterminedbytheexactorderof aminoacids.ThusthecentraldogmaexplainshowthefourletterDNAcodeisquiteliterally turnedintofleshandblood.
