Te Hanganga me te Mahi a te DNA i roto i ngā Mea Ora
Ko te DNA (Deoxyribonucleic Acid) te ngota matua e penapena ana i ngā tohutohu ira i roto i te nuinga o ngā mea ora. Mai i ngā huakita māmā ki te tangata, ka mahi te DNA hei "pukapuka ārahi" e ārahi ana i te tipu o ngā pūtau, te wehewehe, te whakahaere i ngā mahi pākia, me te tuku i ngā āhuatanga mai i tētahi whakatipuranga ki tētahi whakatipuranga. Ko te mārama ki te hanganga me te mahi a te DNA he tūāpapa nui mō te koiora hou, te rongoā, te ahuwhenua, me te hangarau koiora.
Te Mārama ki te DNA me tōna Tūranga i te Ora
Ko te DNA te rauemi ira e kitea ana i roto i ngā pūtau . I roto i ngā rauropi eukaryotic pērā i ngā tipu, ngā kararehe, me ngā harore, ko te DNA te mea nui e rongoa ana i roto i te karihi pūtau (ngā ira-ira), ā, kei roto hoki i ngā whekau pērā i ngā mitochondria me ngā chloroplast. I roto i ngā rauropi prokaryotic pērā i ngā huakita, kei roto te DNA i tētahi wāhi o te cytoplasm e kiia nei ko te nucleoid.
Ko te mahi matua a te DNA he penapena i ngā mōhiohio ira. Kei roto i ēnei mōhiohio te "waehere" mō te hanga pūmua, arā, ngā ngota e mahi ana i te nuinga o ngā mahi koiora o te tinana: te hanga hanganga pūtau, te whakahaere i ngā tauhohenga matū mā roto i ngā whākōkī, me te whakahaere i te tipu me te whakatikatika kiko.
Hanganga Taketake o te DNA: Ngā Nucleotides hei Poraka Hanga
Ko te hanganga o te DNA he mea hanga mai i ngā waeine iti e kiia nei ko ngā nukleotida. E toru ngā wāhanga matua o ia nukleotida:
1. Ko te huka deoxyribose, he huka waro-rima tēnei, koia te "anga" o ngā nucleotides.
2. Ngā rōpū phosphate, e hono ana i tētahi nucleotide ki tētahi nucleotide e whai ake nei hei hanga i tētahi mekameka roa.
3. Ngā turanga hauota, he wāhanga nui ēnei o te kawe i ngā mōhiohio ira.
E whā ngā momo o ngā turanga hauota DNA:
– Āteneni (A)
– Taimini (T)
– Te Hitosina (C)
– Kuanīni (G)
Ko te raupapatanga o ēnei pūtake hauota te mea e pupuri ana i ngā mōhiohio ira. Ki te kī, he rite ngā pūtake hauota ki ngā reta i roto i te arapū, ā, ko tā rātou raupapatanga he hanga "kupu" me "rerenga kōrero" hei tohutohu koiora.
Te Tauira Takirua: He Kitenga Matua i roto i te Koiora
Ko te hanganga DNA tino rongonui ko te helix takirua, i whakamāramahia whānuitia i muri i te rangahau a James Watson rāua ko Francis Crick i te tau 1953, me te tautoko a ngā raraunga diffraction hihi-X mai i a Rosalind Franklin rāua ko Maurice Wilkins. Ko te DNA he miro e rua e takai ana tetahi ki tetahi i roto i te porowhita, he rite ki te arawhata miro.
I roto i tēnei tauira:
– Ko te wāhanga huka-phosphate te taha "kakau" o te arawhata (tuarā).
– Ka hangaia e ngā turanga hauota he "kaupapa" e honoa ana tetahi ki tetahi.
He motuhake ngā takirua turanga:
– Ka honoa tonutia te Adenine (A) me te Thymine (T)
– Ka honoa tonutia te Cytosine (C) ki te Guanine (G)
Ka puta te hononga hauwai i waenga i ngā takirua turanga, ahakoa he ngoikore te hononga takitahi, he tino pumau nā te mea he maha i te taha o te ngota DNA.
Ngā Āhuatanga Tāpiri me te Aronga o ngā Aho DNA
E rua ngā aho DNA he whakakīkī, arā, ko te raupapatanga turanga i tētahi aho ka whakatau i te raupapatanga turanga i tētahi atu. Mena kei tētahi aho te raupapatanga ATCG, ko tōna takirua whakakīkī ko TAGC. He mea nui tēnei āhuatanga mō te tāruaruatanga DNA me te tuku iho ira.
Hei tāpiritanga, ka rere ngā aho DNA e rua i ngā ahunga rerekē, e kiia nei he antiparallel. Ka rere tētahi aho mai i te 5' ki te 3', ko tētahi atu mai i te 3' ki te 5'. Ka rite tēnei ahunga ki te tūranga o ngā ngota waro i runga i te huka deoxyribose, ā, ka whakatau i te mahi a ngā whākōkī i te wā e tārua ana i te DNA.
Te DNA i roto i ngā Chromosome: Te Tākai i ngā Mōhiohio Ira
I roto i ngā rauropi eukaryotic, kāore te DNA e noho noa engari ka whakapotohia ki roto i ngā chromosome. Kei roto i tēnei tukanga whakapoto ngā pūmua histone. Ka takai te DNA i ngā histone hei hanga i ngā hanganga e kiia nei ko ngā nucleosome, kātahi ka whakapikohia anō ki roto i ngā muka chromatin, ā, i te mutunga ko ngā chromosome. He mea nui tēnei takai kia uru te DNA roa ki roto i te karihi pūtau iti, ā, ka āwhina hoki ki te whakahaere i te urunga atu o ngā ira ki te whakaputa, ki te "pānui" rānei e te pūtau.
He rerekē te maha o ngā ira ira i waenga i ngā momo. E 46 ngā ira ira o te tangata (23 ngā takirua), engari he nui ake pea i ētahi tipu.
Te Mahi Matua o te DNA: Te Rokiroki me te Tuku Iho i ngā Mōhiohio
1. Ngā Tohutohu mō te Rokiroki i te Hanga Pūmua
Ka rongoatia e te DNA ngā ira, arā, ngā wāhanga motuhake kei roto ngā tohutohu mō te hanga pūmua mahi, ngā ngota RNA rānei. I roto i te tukanga whakaputa ira, ka "whakamāoritia" te DNA mā roto i ngā wāhanga matua e rua:
– Te Whakawhiti: Ka tāruatia te DNA ki roto i te RNA (ina koa ko te mRNA).
– Te whakamāoritanga: ka whakamāoritia te mRNA ki roto i tētahi raupapa o ngā waikawa amino hei hanga pūmua.
Ko ngā pūmua e whakaputaina ana e whakatau ana i ngā āhuatanga me ngā mahi a ngā pūtau. Hei tauira, ko ētahi ira e whakahaere ana i te hanganga o te hemoglobin i roto i ngā toto toto whero, ko ētahi e whakahaere ana i ngā whākōkī nakunaku.
2. Te Whakakapinga DNA mō te Wehenga Pūtau
I mua i te wehenga o ngā pūtau, me tārua te DNA kia ōrite te tārua o ngā mōhiohio ira ki ia pūtau tamahine. Ka kiia tēnei tukanga he tāruatanga DNA, ā, ka puta i roto i te āhua ā-pūmau: ko ia ngota DNA hou he aho tawhito kotahi me te aho hou kotahi.
Kei roto i te tāruarua ngā whākōkī nui maha, pērā i:
– Helicase, e wetewete ana i te DNA.
– Ko te DNA polymerase, e tāpiri ana i ngā nucleotide hou e ai ki ngā takirua turanga.
– Ko te Ligase, e hono ana i ngā kongakonga DNA, inā koa i te miro e whakaroa ana.
He tino tika te tāruarua nā te mea he āheinga whakatikatika ā-tuhi tō te DNA polymerase ki te whakatika i ngā hapa.
3. Te Whakahaere i te Mahi Pūtau mā te Whakahaere Ira
Ehara i te mea he hohe tonu ngā ira katoa. He tikanga ā ngā pūtau hei whakakā, hei whakaweto rānei i ngā ira ina hiahiatia. Ka kiia tēnei ko te whakahaere ira. Hei tauira, ka whakahohehia e ngā pūtau ate ngā ira e pā ana ki te tango paitini, ko ngā pūtau io ia ka whakahohehia e ngā ira e tautoko ana i te tuku tohu.
Ka awehia hoki te whakahaere ira e ngā āhuatanga epigenetic, arā, ngā huringa kāore e whakarerekē i te raupapa DNA engari e pā ana ki tōna whakaaturanga—pērā i te methylation DNA me ngā whakarerekētanga histone.
Ngā Huringa Ira DNA: He Pūtake o te Rerekētanga me te Take o te Mate
Ka taea e te DNA te whakarerekē i tōna raupapatanga turanga, e kiia nei ko ngā whakarerekētanga ira. Ka puta ngā whakarerekētanga ira nā ngā hapa tāruarua, te pānga ki te irahiko, ngā matū, ngā huaketo rānei. He rerekē ngā pānga:
– Kāore e taea e ngā whakarerekētanga ira te noho pūmau (kāore he pānga).
– He pai ngā whakarerekētanga ira (me whakarato ētahi urutaunga).
– Ka kino pea ngā whakarerekētanga ira, ā, ka puta hoki ngā mate ira.
Ko tētahi tauira o te whakarerekētanga ira e pā ana ki te tangata ko te mate toto totoka, he mate e puta mai ana i ngā huringa o te ira hemoglobin. Heoi, i roto i te horopaki whanaketanga, ko ngā whakarerekētanga ira he pūtake nui hoki o te rerekētanga ira e āhei ai te kōwhiringa taiao ki te mahi.
Te DNA me te Whanaketanga o te Pūtaiao
He maha ngā putanga hou kua puta mai i ngā rangahau DNA, pērā i:
– Whakamātautau ira hei kite i ngā mate tuku iho, i ngā mōrearea rānei.
– Ngā rangahau DNA mō te tautuhi takitahi.
– Te hangarau ira i roto i te ahuwhenua (ngā hua ātete ki ngā riha) me te rongoā (te hanga insulin).
– Te rongoā ira me te hangarau CRISPR-Cas9, e āhei ai te whakatika i te DNA kia tika ake.
E whakaatu ana tēnei whanaketanga ehara i te mea he ariā koiora noa iho te DNA, engari ko te tūāpapa hoki o ngā hangarau o muri mai.
Whakamutunga
He ngota ngota te DNA mō te ora nā te mea ka rongoa, ka tuku, ka whakaatu hoki i ngā mōhiohio ira. Nā tōna hanganga takirua-porowhita, te takirua turanga tautoko, me te takai i roto i ngā ira-kōroma ka taea e te DNA te mahi pumau me te whai hua. Kei roto i ngā mahi a te DNA te hanga pūmua, te tāruarua i te wā o te wehenga pūtau, me te whakahaere i te mahi pūtau mā te whakaaturanga ira. I tētahi atu taha, ka taea e ngā whakarerekētanga ira i roto i te DNA te waiho hei pūtake o te kanorau ira me te take o te mate. Me ngā whanaketanga o te pūtaiao, kei te whakatuwhera tonu te mārama ki te DNA i ngā whai wāhitanga nui mō te hangarau koiora, te rongoā, me te whakaoti rapanga tangata.
Ki te hiahia koe, ka taea hoki e au te tāpiri i tētahi hoahoa māmā (hei whakaahuatanga) ka taea rānei e au te hanga i tētahi putanga "rongonui" ake o tēnei tuhinga mā ngā ākonga kura waenga/kura tuarua.
