Hanganga RNA i roto i te Pūnaha Ira
Ko te waikawa ribonucleic (RNA) he ngota matua i roto i te pūnaha ira o ngā mea ora katoa. Ahakoa e kiia ana te DNA ko te "rokiroki" o ngā mōhiohio ira, he mahi hihiri ake tā te RNA: ka tārua, ka kawe, ka whakamāori, ā, ka whakarite i aua mōhiohio kia taea ai te whakamāori ki ngā mahi koiora. Ko te ahurei o te RNA ehara i te mea ko tana mahi anake engari ko tōna hanganga ngāwari me te kanorau. Mā te hanganga o te RNA ka taea e tēnei ngota te mahi i ngā mahi maha i te wā kotahi, mai i te takawaenga i te whakaaturanga ira ki te whakaoho i ngā tauhohenga matū koiora. Ka matapakihia e tēnei tuhinga te hanganga o te RNA me tōna whanaungatanga ki tana mahi i roto i te pūnaha ira.
1. Te Mārama ki te RNA me ōna wāhanga
He pūhui te RNA i titoa mai i ngā waeine tāruarua e kiia nei ko ngā nucleotide. E toru ngā wāhanga matua o ia nucleotide RNA: he huka ribose, he rōpū phosphate, me te turanga hauota. Kei roto i ngā turanga hauota i roto i te RNA ko te adenine (A), te guanine (G), te cytosine (C), me te uracil (U). Ko ngā rerekētanga nui mai i te DNA ko te whakamahinga o te uracil hei utu mō te thymine me te momo huka e whakamahia ana (ribose i roto i te RNA, te deoxyribose i roto i te DNA).
Nā te noho mai o te rōpū hydroxyl (-OH) i runga i te ngota waro 2' o te ribose ka nui ake te tauhohenga o te RNA, ā, ka iti ake te pumau i te DNA. Heoi, he pai tēnei "kore pumau" i roto i ngā horopaki koiora nā te mea he maha ngā wā ka hangaia te RNA hei ngota rangitahi ka tere te hanga, ka tere hoki te pakaru i te mea e hiahiatia ana e te pūtau.
2. Hanganga tuatahi: te raupapatanga nucleotide hei waehere mōhiohio
Ko te hanganga tuatahi o te RNA e pā ana ki te raupapatanga o ngā nucleotide i te mekameka RNA. Ka rongoatia e tēnei raupapatanga ngā mōhiohio—hei tauira mō te hanganga pūmua, hei tohu whakahaere hoki. I roto i te RNA karere (mRNA), ka whakaritea te raupapatanga nucleotide ki roto i ngā codon turanga-toru ka whakamāoritia ki roto i te raupapatanga waikawa amino o te pūmua. I roto i ētahi atu momo RNA, pērā i te rRNA, te tRNA rānei, ka whakatau hoki te hanganga tuatahi i te tūranga o ngā rohe matua e hanga ana i ngā takai āhuatanga me ngā wāhi mahi.
Kāore te hanganga tuatahi e mahi takitahi. I roto i te RNA, ka taupatupatu ngā mōhiohio "waehere" me te "hanganga": ehara i te mea ko te raupapatanga turanga anake te mea e whakatau ana i te karere ira engari e whakatau ana hoki i te kaha o te RNA ki te hanga i ngā takirua turanga ā-roto e whakaputa ana i ngā hanganga taumata teitei ake.
3. Hanganga tuarua: ngā takirua turanga me ngā takai noa o te RNA
Ko te hanganga tuarua o te RNA ko te tauira o ngā takirua turanga ā-roto e hanga ana i ngā huānga pēnei i ngā porowhita, ngā titi makawe, ngā koropiko, ngā pupuhi, me ngā hononga. Ko te kaupapa matua o te takirua turanga i roto i te RNA e whai ana i te ture tāpiri: he takirua A me te U, me ngā takirua G me te C. Hei tāpiri, he maha ngā wā ka hangaia e te RNA ngā takirua turanga kore-tika pēnei i te wiri G–U, he tino pumau, he mea nui hoki mō te mahi a te maha o ngā RNA.
Ka puta te takai tuarua nā te mea ka taea e te aho RNA kotahi te takai anō me te hanga hononga hauwai i waenga i ngā turanga tautoko i ngā wāhi rerekē. He mea nui tēnei hanganga tuarua nā te mea:
1. Whakaū i ngā ngota RNA i roto i te taiao pūtau hihiri.
2. Te hanga i ngā wāhi mōhio mō ētahi atu pūmua, RNA rānei.
3. Te whakahaere i ngā tukanga koiora, hei tauira te whakatau mēnā he ngāwari te whakamāori, te aukati rānei i te mRNA.
Ko tētahi tauira mārama ko te tRNA, he hanganga tuarua tōna e rite ana ki te "rau kōwhai." He maha ngā ringa o tēnei hanganga, tae atu ki te ringa anticodon me te ringa kaiwhiwhi waikawa amino, ā, he mahi motuhake tā ia ringa.
4. Hanganga tuatoru: āhua toru-ahu e whakatau ana i te mahi
Ko te hanganga tuatoru o te RNA he āhua toru-ahu e puta mai ana i ngā taunekeneke atu i waenga i ngā wāhanga o te hanganga tuarua. I tēnei wā, ka hangaia e te RNA he takai matatini mā roto i ngā kaha maha, pērā i ngā here hauwai tāpiri, ngā taunekeneke whakapūpū turanga, me te āwhina o ngā katote (hei tauira, Mg²⁺) e whakakore ana i te utu kino i runga i te tuara phosphate.
He mea nui te hanganga tuatoru nā te mea he maha ngā mahi RNA e whakawhirinaki ana ki tōna āhua toru-ahu. Hei tauira:
– He āhua-L te āhua o te tRNA i roto i te wāhi toru-ahu. Mā tēnei āhua ka taea te whakanoho tika i te pito here-waikawa amino ki te anticodon e pānui ana i te codon mRNA.
– Ko te rRNA te pūtake hanganga o te ribosome, ā, ko tōna kopa tuatoru ka hanga i tētahi "wheketere" whakamāoritanga tika.
– Ko ngā ribozyme, he RNA whakakorikori, e whakawhirinaki nui ana ki ngā momo tuatoru hei waihanga i ngā pae hohe pērā i ngā whākōkī pūmua.
Nō reira, ehara te RNA i te "karere" noa iho. Ka taea e ia te noho hei hanganga koiora matatau, kaha hoki.
5. Ngā momo RNA me ngā whanaungatanga hanganga-mahi
I roto i te pūnaha ira, he maha ngā momo matua o te RNA e tino mōhiotia ana:
a. mRNA (RNA karere)
Ka haria e te mRNA ngā mōhiohio ira mai i te DNA i roto i te karihi (i roto i ngā eukaryote) ki ngā ribosome i roto i te cytoplasm hei whakamāoritanga ki ngā pūmua. Ko te hanganga o te mRNA eukaryotic he taupoki 5', he rohe kāore i whakamāoritia (UTR), he anga pānui (ORF), me te hiku poly-A i te pito 3'. Ka pāngia e ēnei huānga te pumau o te mRNA, te pai o te whakamāoritanga, me te taunga i roto i te pūtau.
b. tRNA (RNA whakawhiti)
Ka mahi te tRNA hei urutau e hono ana i ngā codon mRNA ki ō rātou waikawa amino e rite ana. Mā te hanganga tuarua o te rau cloverleaf me te hanganga tuatoru āhua-L ka taea e te tRNA te: (1) mōhiotia e te whākōkī aminoacyl-tRNA synthetase, (2) tomo ki te ribosome, me te (3) hono tika i ngā anticodon ki ngā codon.
c. rRNA (RNA ribosomal)
He wāhanga matua te rRNA o ngā ribosome, ā, he mahi nui tāna i roto i te tukanga whakamāori. He mea whakamīharo, he "ribozymes" nunui ngā ribosome: ko te wāhanga whakatere o te hanganga hononga peptide ka mahia e te rRNA, ehara i te pūmua. Ko te mahi angitu o ngā ribosome e whakawhirinaki nui ana ki te hanganga matatini o te rRNA.
d. RNA whakahaere
Haunga ngā momo matua e toru, he maha ngā RNA iti e mahi ana ki te whakahaere i te whakaaturanga ira, pērā i te miRNA (microRNA), te siRNA (RNA iti e pokanoa ana), me te lncRNA (RNA roa kāore e whakakōwaea). He maha ngā wā kei roto i ngā hanganga RNA whakahaere he titi makawe, he rohe takirua-pūtake rānei, e āhei ai rātou ki te here ki ngā mRNA ūnga me te aukati i te whakamāoritanga, te whakaoho rānei i te pakaru o te mRNA.
6. RNA i roto i te tāruarua, te tuhi, me te tukatuka ira
Kei roto i te RNA ngā wāhanga rerekē o te rere o ngā mōhiohio ira. I te wā o te tuhi, ka hangaia e te RNA polymerase te RNA i runga i te tauira DNA. I roto i ngā eukaryote, ka tukatukahia te RNA hou (pre-mRNA): te tāpiri taupoki, te honohono intron, me te polyadenylation. Ka taea e te hanganga RNA te awe i te honohono, nā te mea ka taea e ētahi kopa te huna, te whakanui rānei i ngā wāhi honohono.
Kei roto hoki te RNA i te tāruarua o ētahi huaketo. I roto i ngā huaketo RNA, ko te rauemi ira ko te RNA, nō reira he maha ngā wā ka hangaia te hanganga RNA huaketo kia tino whai hua: ka taea te mahi hei ira me te mRNA. Ka whakamahia e ētahi huaketo ngā hanganga RNA motuhake hei karo i te pūnaha parepare o te pūtau, hei whakanui ake rānei i te whai huatanga o te tāruarua.
7. Te tirohanga whanaketanga: Te ariā o te ao RNA
Ko tētahi o ngā ariā matua o te koiora whanaketanga ko te ariā "ao RNA". E kī ana tēnei ariā i ngā wāhanga tōmua o te ora, tera pea i mahi te RNA i ngā mahi takirua hei putunga mōhiohio ira me te whakakorikori mō ngā tauhohenga, i mua i te wehenga hei DNA (he pumau ake mō te rokiroki) me ngā pūmua (he rerekē ake mō te whakakorikori). Ko te ngāwari o te hanganga RNA e tautoko ana i tēnei ariā, i te mea ka taea e te RNA te whakakōrero mōhiohio i te wā e takai ana ki ngā pae hohe whakakorikori.
Whakamutunga
Ko te hanganga o te RNA te mea nui ki tana mahi i roto i te ira. Mai i tōna hanganga tuatahi, e pupuri ana i ngā raupapatanga nucleotide, ki tōna hanganga tuarua, e hanga ana i ngā kopa rite ki te titi makawe, ki tōna hanganga tuatoru, e hanga ana i ngā mahi matatini e toru-ahu, ka whakaatuhia e te RNA ngā āheinga ahurei hei ngota maha-mahi. Mā ngā āhua kanorau o te RNA ka taea e ia te mahi hei kaikawe mōhiohio, hei urutau whakamāoritanga, hei kaihanga ribosome, hei kaiwhakahaere whakaaturanga ira, tae noa ki te whakakorikori koiora. Ko te mārama ki te hanganga o te RNA ko te mārama ki tētahi o ngā turanga taketake o te ora, e whakatakoto ana i te ara mō ngā tono hangarau koiora me te hauora pēnei i ngā maimoatanga e hangai ana ki te RNA, ngā kano kano mRNA, me te whakahaere tika i te whakaaturanga ira.
