Te Whakakotahitanga Ira i roto i te Koiora Ngota
Ko te whakakotahitanga ira tētahi o ngā tukanga tino taketake o te koiora ngota, e āhei ai ngā rauemi ira ki te whakawhiti, ki te whakarite anō, ki te whakakotahi anō rānei. He mahi nui tā tēnei tukanga ki te waihanga i ngā rerekētanga ira, ki te pupuri i te pumau o te ira, me te whakatika i ngā kino o te DNA. I roto i ngā rauropi ora—mai i te huakita ki te tangata—he taputapu taiao te whakakotahitanga hei pupuri i te oranga me te urutau ki ngā huringa taiao. I roto i te horopaki o te koiora ngota hou , ko te mārama ki te whakakotahitanga ira te pūtake mō ngā hangarau maha pērā i te hangarau ira, te mahere ira, me te rongoā ira.
Te Mārama ki te Whakakotahitanga Ira
I te whakarapopototanga, ko te whakakotahitanga ira te tukanga whakawhiti ira i waenga i ngā ngota DNA e rua, i ngā ira-ira rānei e rua. Ko te hua he huinga ira hou e rerekē ana i te whakaritenga o mua. Ka taea te whakakotahitanga māori i roto i ngā pūtau (hei tauira, i te wā e hangaia ana ngā kēmu i roto i ngā eukaryote) ka taea rānei te hanga i roto i te taiwhanga (hei tauira, mā te whakamahi i ngā tikanga DNA whakakotahi).
He mea nui tēnei tukanga nā te mea ehara te DNA i te hanganga pumau. He uaua tonu te aro atu ki ngā wero o te ira: te tāruaruatanga kāore i te tino tika, te pānga ki te irahiko, ngā matū, me ngā pēhanga kōwhiringa. Mā te whakakotahitanga anō ka taea te wikitoria i ēnei wero mā te whakatika me te whakarite anō i ngā mōhiohio ira.
Ngā Momo Whakakotahitanga Ira
I roto i te koiora ngota , ka wehea te whakakotahitanga ira ki ētahi momo matua:
1. Te Whakakotahitanga Taurite
Ka puta te whakakotahitanga ōrite i waenga i ngā ngota DNA e rua he tino ōrite, he ōrite rānei ngā raupapatanga. He tikanga nui tēnei i roto i te meiosis i roto i ngā eukaryote, e whakaputa ana i te rerekētanga ira i roto i ngā uri. Hei tāpiri, he mahi nui anō hoki tā te whakakotahitanga ōrite. i roto i te whakatikatika DNA, inā koa i roto i te whakatika i ngā motu o te aho takirua.
Ko te tauira tino rongonui ko te "whiti" i te wā o te prophase I o te meiosis, ina whakawhiti wāhanga ngā ira ōrite. Ka whakanui ake tēnei whakawhiti i te kanorau ira, ā, ka āwhina i te wehenga ira kia haere tonu i te āhua noa.
2. Whakakotahitanga Kore-Homologous
Kāore i rite ki te whakakotahitanga ōrite, kāore e hiahiatia he ōritetanga raupapa teitei mō te whakakotahitanga kore-taurite. Ka taea e tēnei tukanga te whakaputa i ngā huringa nui ki te ira, pērā i te mukunga, te tāruarua, te hurihanga, te whakawhiti rānei. I ētahi wā, ka taea e te whakakotahitanga kore-taurite te whakaputa i ngā hua kino, arā, te whakaoho i ngā whakarerekētanga ira, i ngā hapa ira rānei.
Ko tētahi tikanga e pā ana ko te Non-Homologous End Joining (NHEJ), he tikanga mō ngā pūtau ki te whakatika tere i ngā pakaru DNA aho-rua mā te hono tika i ngā pito o te DNA. Ahakoa he whai hua, he nui ake te mōrearea o te NHEJ nā te mea ka puta he hapa iti pēnei i te ngaronga, te tāpiri rānei o ētahi nucleotides.
3. Whakakotahitanga motuhake ki te pae
Ka puta tēnei whakakotahitanga i ngā wāhi DNA motuhake e mōhiotia ana e ngā whākōkī motuhake. He mea noa tēnei tikanga i roto i ngā huaketo, ngā plasmid, me ngā huakitaHei tauira, ina whakaurua e te phage (he huaketo kitakita) tōna ira ki roto i te chromosome kitakita, ko ngā whākōkī e whai wāhi ana ka kiia ko ngā recombinases, e tapahi ana, e hono ana i te DNA i te raupapa ūnga.
He mea nui te whakakotahitanga motuhake ki tētahi pae i roto i te hangarau koiora nā te mea ka taea te whakahaere tika ake i te DNA, hei tauira i roto i te pūnaha Cre-Lox e rongonui ana i roto i te rangahau ira.
Te Tikanga Whakakotahitanga o te Ngota
Hei mārama ki te whakakotahitanga ira, he mea nui kia mārama ki ōna tikanga i te taumata ngota. Ahakoa he rerekē ngā taipitopito i runga i te momo whakakotahitanga, ka taea te whakamārama i ētahi mahi whānui.
I roto i te whakakotahitanga ōrite, ka tīmata te tukanga me te wehenga o te DNA aho-rua. Kātahi ka "tukatuka mutunga" te pūtau hei whakaputa i ngā pito DNA aho-kotahi. Ka rapu ēnei pito i ngā raupapa ōrite i runga i ētahi atu ira-ira, ka hua ake te whakaekenga o ngā aho, ka hanga i ngā hanganga e rite ana ki ngā "koropiko-D." Kātahi ka hanga he hononga Holliday, he hanganga DNA honohono ka taea te tapahi me te hono anō, ka puta he huinga ira hou.
Ko ngā pūmua nui o tēnei tukanga ko te RecA i roto i ngā huakita me te Rad51 i roto i ngā eukaryote. Ka āwhina ēnei pūmua i te whakahāngaitanga o ngā raupapatanga ōrite, ā, ka āwhina hoki i te whakawhiti i ngā aho DNA.
I roto i te NHEJ, ka kitea ngā pito o ngā wehenga DNA e ngā pūmua here-pito, kātahi ka whakarārangihia, ka honoa anō. Kāore tēnei tikanga e hiahia ki tētahi tauira ōrite, ka tere ake engari kāore i te tino tika.
Te Tūranga o te Whakakotahitanga i roto i te Kanorau Ira
Ko te whakakotahitanga tētahi pūtake nui o te rerekētanga ira i roto i ngā taupori. I roto i ngā eukaryote, ka puta mai i te meiosis ngā gametes me ngā huinga rerekē o ngā ira. Mā te whakawhiti ka puta mai ngā ira e kawe ana i te ranunga o ngā ira mai i ngā mātua e rua. He mea nui tēnei mō te whanaketanga nā te mea ko te rerekētanga ira te "rauemi mata" mō te mahi a te kōwhiringa taiao.
I roto i ngā huakita, ahakoa kāore e pāngia e te meiosis, ka puta tonu te whakakotahitanga mā roto i ngā tukanga whakawhiti ira whakapae pērā i te whakawhiti (te tango i te DNA mai i te taiao), te whakawhiti (ka haria e ngā huaketo), me te whakawhiti (te whakawhiti i ngā plasmid i waenga i ngā pūtau). Mā ēnei tukanga ka taea e ngā huakita te tere whiwhi i ngā āhuatanga hou, pērā i te ātete ki ngā paturopi.
Te Whakakotahitanga me te Whakatikatika i te DNA
Ehara i te mea ko te whakakotahitanga ira anake te mea ka puta he rerekētanga engari he mahi anō hoki ki te pupuri i te pumau o te ira. Ko ngā pakaru DNA aho-rua tētahi o ngā momo kino tino morearea nā te mea ka taea e rātou te arahi ki te ngaronga o ngā mōhiohio ira me te mate pūtau. Ka taea e te whakakotahitanga homologous te whakatika tika i ēnei pakaru mā te whakamahi i ngā chromatids tuahine hei tauira. Nō reira, ko te whakakotahitanga he tikanga "tiaki" nui mō te oranga o ngā rauropi.
Ka taea e ngā hapa i roto i te whakakotahitanga te arahi ki ngā momo mate. I roto i te tangata, ko te whakakorenga o ngā tikanga whakatika DNA mā te whakakotahitanga ka piki ake te mōrearea o te mate pukupuku nā te kohikohinga o ngā whakarerekētanga ira. Hei tauira, ko ngā whakarerekētanga ira i roto i ngā ira BRCA1 me BRCA2 e pā ana ki te ngoikore o te whakatikanga DNA me te pikinga o te mōrearea o te mate pukupuku ū me te mate pukupuku whatukuhu.
Te Whakakotahitanga i roto i te Hangarau Koiora me te Hangarau Ira
Ko te kupu "DNA hangarua" e whakamahia whānuitia ana i roto i te hangarau koiora, e pā ana ki te DNA i honoa mai i ngā pūtake rerekē e rua. Mā tēnei tikanga ka taea te whakauru i ngā ira motuhake ki roto i ngā plasmid, kātahi ka whakaurua ki roto i ngā huakita, ki ētahi atu pūtau rānei hei whakaputa. Mā tēnei, ka taea e te tangata te whakaputa i ngā pūmua nui pērā i te insulin, ngā homoni tipu, ngā kano kano rānei.
Hei tāpiritanga, ka whakamahia hoki te whakakotahitanga i roto i te hanganga o ngā rauropi whakawhiti ira, te mahere ira, me te whakaputa hua he āhuatanga pai ake (hei tauira, te ātete ki ngā pepeke, te manawanui rānei ki te tauraki). I roto i ngā rangahau, mā ngā tikanga whakakotahitanga motuhake ki te wāhi pērā i te pūnaha Cre-Lox ka taea e ngā kaipūtaiao te "whakaweto" te "whakakā" rānei i ngā ira motuhake i ngā kiko me ngā wā motuhake, kia taea ai te ako tika ake i te mahi a te ira.
Kei roto hoki i te whanaketanga o te hangarau CRISPR-Cas9 te whakakotahitanga anō. I muri i te tapahi o te DNA e Cas9, ka taea e ngā pūtau te whakatika i te pakaru mai i te NHEJ, te homology-directed repair rānei (HDR), e whakamahi ana i ngā mātāpono o te whakakotahitanga ōrite hei whakauru i te raupapatanga e hiahiatia ana.
Whakamutunga
Ko te whakakotahitanga ira i roto i te koiora ngota he tukanga nui e hono ana i te rerekētanga ira, te whakatikatika DNA, me te pumau o te ira. Mā te whakakotahitanga ira kotahi ka āwhina i te whakaputa i te kanorau me te whakatika tika i ngā kino o te DNA, ko te whakakotahitanga kore-ira kotahi me te whakakotahitanga motuhake he mahi nui ki ngā whanaketanga ira me ngā taunekeneke i waenga i ngā rauropi pēnei i te huakita me te huaketo. I tēnei wā hou, kua hua ake te māramatanga ki te whakakotahitanga i te whānuitanga o ngā tono hangarau koiora, mai i te hanga rongoā ki te whakatika ira. I te haere tonu o te rangahau i tēnei mara, ka noho tonu te whakakotahitanga ira hei kaupapa matua i roto i te māramatanga ki te ora i te taumata ngota me te whakawhanake i ngā otinga mō ngā wero hauora me te kai ā muri ake nei.
