Te Whakaritenga, te Tākai rānei o te DNA i roto i ngā Pūtau
I te taumata ngota, ko te ora i runga i te Ao e hangai ana ki ngā mōhiohio ira kei roto i ngā ngota DNA. Ko te DNA, ko te waikawa deoxyribonucleic rānei, he pūmua e penapena ana i ngā tohutohu koiora e tika ana mō te whanaketanga, te mahi, te tipu, me te whakaputa uri o ngā mea ora katoa. Ahakoa e whā noa iho ngā momo nucleotide o te DNA—adenine (A), thymine (T), cytosine (C), me te guanine (G)—he tino uaua te whakaritenga i roto i ngā pūtau. Me tūhuratia ake te whakaritenga, te tākai rānei o te DNA i roto i ngā pūtau.
Hanganga Taketake o te DNA
He āhua porowhita rua te DNA, i kitea e James Watson rāua ko Francis Crick i te tau 1953. He rite tēnei hanganga ki tētahi arawhata piko, ko ngā takirua turanga hei taumata, ko te tuara huka-phosphate hei kakau. Ko ngā takirua turanga i waenganui i te adenine me te thymine, me te cytosine me te guanine, e honoa ana e ngā hononga hauwai, e whakarato ana i te pumau ki te porowhita takirua.
Ngā Histones me ngā Nucleosomes
I roto i te karihi o te pūtau eukaryotic, ka taea e te ngota DNA te roa i ētahi mita ina totoro katoa. Ko te whakauru i tēnei ngota nui ki roto i te karihi he torutoru noa iho te whānui o te micrometer me whai tikanga takai matatau. Ko tētahi huānga matua o te takai DNA ko ngā pūmua e kiia nei ko ngā histones.
He pūmua taketake ngā histones e nui ana i ngā waikawa amino lysine me te arginine, e āhei ai rātou ki te taunekeneke pai ki te DNA waikawa. Ka takai te DNA ki ngā histones, ka hanga he hanganga e mōhiotia ana ko ngā nucleosome. Kei roto i ia nucleosome he tata ki te 147 ngā takirua turanga o te DNA e takai ana ki tētahi rōpū o ngā histones e waru, ka hanga ko te waeine takai taketake o te chromatin. He rite tēnei mekameka o ngā nucleosome ki tētahi "aho o ngā pīrere" i raro i te karuārai.
Te Chromatin me ngā Chromosome
Ka haere tonu te takai DNA i ngā taumata teitei ake, ka whakaritea ngā nucleosome ki roto i tētahi hanganga kiato ake, kia raupapa ake hoki e kiia nei ko te chromatin. E rua ngā momo matua o te chromatin: te euchromatin me te heterochromatin. Ko te euchromatin te momo tuwhera ake, ā, he kaha ake te whakawhitiwhiti kōrero, ko te tikanga he ngāwari ake te uru atu o te DNA i roto i ēnei rohe ki te mīhini whakawhitiwhiti kōrero. He rerekē, he kaha ake te heterochromatin, ā, he maha ngā wā e hono ana ki te DNA kāore e kaha te whakawhitiwhiti kōrero.
Ko te whakaritenga anō ka hanga i ngā ira-kōromō, arā, ngā hanganga taumata teitei rawa o te takai ira-kōromō, e kitea ana i te wā o te wehenga pūtau. Ko ngā ira-kōromō te momo ira-kōromō tino kiato, ā, ka whakarite i te tāruaruatanga ira-kōromō tika me te kore e ngaro ngā wāhanga nui i te wā o te mitosis me te meiosis. Hei tauira, e 46 ngā ira-kōromō o te tangata i roto i ia pūtau tinana.
Te Ture mō te Tākai DNA
Ehara te takai DNA i te tukanga pumau; he mahi hihiri, ā, he maha ngā āhuatanga e pāngia ana. Ka taea e ngā whakarerekētanga histone, pērā i te acetylation, te methylation, te phosphorylation, me te ubiquitination, te whakarerekē i ngā taunekeneke i waenga i te DNA me ngā histone, ā, ka pā ki te kiato chromatin me te urunga o te DNA mō te tuhi. Hei tauira, ko te acetylation histone e hono ana ki te euchromatin me te tuhi hohe, ko te methylation ka whai wāhi ki te hanganga o te heterochromatin.
Haunga ngā histones, kei reira anō ngā pūmua whakahou chromatin ka taea te neke, te whakaiti, te hanga anō rānei i ngā tūranga nucleosome, ka whakatikatika ake i te urunga ira. Ka mahi tahi ēnei āhuatanga katoa ki te whakapai ake i te whakahaere DNA kia tutuki ai ngā hiahia pūtau hihiri.
Te Tākai DNA i roto i ngā Prokaryote
He rerekē ngā huakita me ētahi atu rauropi prokaryotic i ngā eukaryotes, he porowhita te DNA o ngā huakita me ētahi atu rauropi prokaryotic, kaua i te rārangi, ā, kāore he karihi e herea ana e te kiriuhi. Ahakoa he māmā ake, he rite tonu te hiranga o te takai DNA i roto i ngā prokaryotes. I roto i ngā huakita, ka whakakīia te DNA mā te awhina o ngā pūmua pēnei i te HU me te IHF, e whakau ana i te supercoiling me te whakahaere i te hanganga nucleoid.
Te Hiranga o te Tākai DNA
Ehara i te mea ko te penapena i ngā mōhiohio ira anake te kaupapa o te takai DNA whai hua, engari ko te whakahaere anō hoki i te mahi a te ira. Ka taea e te tūranga me te mātotoru o te chromatin te awe i te whakaaturanga ira, ā, koinei te kaupapa matua o te rangahau nui i roto i te epigenetics. Mā te ako i ngā tauira epigenetics ka taea te whakarato māramatanga ki ngā momo āhuatanga hauora me ngā mate, tae atu ki te mate pukupuku me ngā mate whanaketanga.
Hei tauira, ko ngā panonitanga o ngā tauira tākai DNA ka arahi pea ki te whakaputanga ira rerekē, e hono ana ki te whanaketanga o te mate pukupuku. Ko ngā rongoā e aro ana ki ngā whakarerekētanga histone, ki te hanganga chromatin rānei, e whakaatu ana i te kaha ki te rongoā i ngā mate i puta mai i te ngoikore o te whakahaere epigenetic.
Whakamutunga
He tukanga uaua, taipitopito hoki te whakahaere, te takai rānei i te DNA i roto i ngā pūtau, he mahi nui tēnei i roto i te oranga. Ehara i te mea ko te takai DNA anake te mea e pā ana ki te pumau o ngā ira i te wā o te wehenga pūtau, engari he kaiwhakahaere matua anō hoki, e whakahaere ana i ngā ira e whakaatuhia ana i te wā tika me te nui tika. Mā te mārama ki ngā taipitopito o te takai DNA ka puta he māramatanga hohonu ki ngā kaupapa matua o te koiora pūtau, ā, ka whakatakoto i te ara mō te whanaketanga o ngā rongoā hou mō ngā mate ira me ngā mate epigenetic. Hei tētahi o ngā mea ngaro tino whakamere i roto i te koiora ngota, ka haere tonu te rangahau i tēnei wāhanga ki te tuku i ngā wero me ngā whai wāhitanga whakahihiri mō ngā kaipūtaiao puta noa i te ao.
