Ngā Mahi a te Pūtau Pūtau me tana Whakahaere i ngā Mahi a te Pūtau
Ko te karihi tētahi o ngā whekau tino nui i roto i ngā pūtau eukaryotic—ko ērā e kitea ana i roto i ngā kararehe, ngā tipu, ngā harore, me ngā pūmua. E kiia ana ko te "pokapū whakahaere" o te pūtau nā te mea kei reira te rauemi ira (DNA), e whakahaere ana i te nuinga o ngā tukanga ora o te pūtau. Heoi, ko te mahi a te karihi he mea nui atu i te penapena noa i te DNA. He mahi kaha anō hoki tāna ki te ārahi i te wā e "whakakāhia" ai, e "whakawetohia ai" rānei ētahi ira, me pēhea te whakaputa pūmua, me pēhea te urupare a te pūtau ki ngā huringa taiao. Mā roto i ngā tikanga kua whakaritea, ka whakahaere te karihi i ngā mahi pūtau mai i te tipu me te wehenga ki te whakatikatika me te whakarite i te mate o te pūtau.
Hanganga Karihi: He aha te Hiranga o tōna Āhua?
Hei mārama ki tana mahi, me titiro tātou ki ngā wāhanga matua o te karihi. He porowhita, he porotītaha rānei te āhua o te karihi, ā, he takai karihi tōna e karapotia ana e tētahi taupoki karihi, e rua ngā paparanga o ngā phospholipid. Kāore tēnei taupoki karihi i tino hiritia; engari, kei roto ngā pūwero karihi e mahi ana hei "kūaha" mō ngā ngota pēnei i te RNA me ngā pūmua ki te tomo me te puta.
He maha ngā wāhanga nui o te pūmua:
1. Chromatin: He huinga o ngā pūmua DNA me te histone. Ka taea e te chromatin te whakapoto hei chromosomes ina wehea ngā pūtau.
2. Nucleolus: He hanganga matotoru i roto i te nucleus, koinei te wāhi matua o te hanganga o te ribosome.
3. Nucleoplasm: Ko te wai/pūnaha kei reira te chromatin me te nucleolus, kei roto ngā whākōkī me ngā āhuatanga whakahaere.
4. Papa karihi (papa karihi): He whatunga pūmua e tautoko ana i te āhua o te karihi, ā, e āwhina ana ki te whakarite i te chromatin.
Mā tēnei hanganga ka taea e te karihi te whakahaere pai. Mā ngā pūwero karihi ka tere te whakawhitiwhiti kōrero i waenga i te karihi me te cytoplasm, ā, mā te whakaritenga o te chromatin ka awe i ngā ira ka taea te uru atu hei whakahohe.
Te Mahi Matua o te Pūnaha Matua: Te Rokiroki me te Tiaki i ngā Mōhiohio Ira
Ko te mahi matua o te karihi ko te penapena i te DNA, te mahere o te ora. Ka penapena te DNA i ngā mōhiohio e hiahiatia ana hei hanga i ngā pūmua me te RNA, ā, ko ēnei te mea hei whakatau i te hanganga me te mahi a ngā pūtau. Mena ka pakaru te DNA, ka kore rānei e penapena tika, ka pāngia ngā pūtau e te ngoikore o te mahi, te whakarerekētanga ira, tae noa ki te mate.
Ka tiakina hoki e te karihi te DNA mai i ngā āhuatanga matū o te cytoplasm ka taea te kino i ngā rauemi ira. Nā te noho mai o te kiriuhi karihi, ngā matatini pūmua tiaki, me ngā tikanga whakatika DNA ka waiho te karihi hei wāhi haumaru mō te penapena i ēnei mōhiohio.
Te Pūtake hei Pūtake Whakahaere Ira: Te Whakahaere i te Mahi a te Pūtau
Ko te whakahaere i te mahi a te pūtau ka puta tuatahi mā te whakahaere i te whakaaturanga ira, arā, te tukanga whakatau ko ēhea ira ka whakamahia (ka whakaatuhia) me te wā. Ahakoa he rite tonu te DNA o ngā pūtau katoa o te rauropi (hei tauira, ngā pūtau kiri me ngā pūtau io), he rerekē rawa ā rātou whanonga nā te mea he rerekē te whakahaere a te karihi i ngā ira e mahi ana.
I roto i ngā kupu māmā, ko te rere o ngā mōhiohio koia tēnei:
DNA → RNA → Pūmua
Ko ngā pūmua te hunga e mahi ana i te nuinga o ngā mahi a te pūtau, pērā i te hanga hanganga pūtau, te tere ake i ngā tauhohenga matū (ngā whākōkī), te kawe tohu, me te whakahaere i te kawe. Nō reira, ina whakahaere te karihi i te hanga RNA, koia te mea e whakatau ana ko ēhea ngā pūmua ka hangaia, ā, koia te mea e whakahaere ana i te whanonga o te pūtau.
1. Te Whakamāoritanga: Te Hipanga Tuatahi o te Whakahaere Karihi
Ko te tukanga tuatahi o te whakaaturanga ira ko te whakawhiti ira, arā, ko te hanganga o te RNA mai i te DNA. Ko te whākōkī matua e whai wāhi ana ko te RNA polymerase, e pānui ana i te raupapatanga DNA, ā, e hanga ana i tētahi tārua o taua mea hei RNA (hei tauira, mRNA).
Engari kāore te whakawhiti kupu e puta noa mai. Mā te pūtake e whakahaere mā roto i:
– Ngā kaiwhakatairanga me ngā whakarei ake: Ngā wāhanga o te DNA e whakatau ana mēnā ka tuhia he ira.
– Ngā take whakawhiti kupu: Ngā pūmua whakahaere e piri ana ki te DNA hei āwhina, hei aukati rānei i te RNA polymerase.
– Te whakarerekētanga o te chromatin: He māmā ake te tuhi i te DNA "tuwhera" (euchromatin), ko te DNA "kati" pūmau (heterochromatin) ia he kore mahi.
Ara, ka taea e te karihi te whakaae, te aukati rānei i te "pānui" o ētahi ira ina hiahiatia.
2. Te Tukatuka RNA: Te Tātari i ngā Mōhiohio i mua i te Wehenga atu i te Pūnaha
I roto i ngā pūtau eukaryotic, kāore anō kia rite te RNA hou (pre-mRNA) mō te whakamahi. Me tukatuka i roto i te karihi mā roto i:
– Te tāpiri i te taupoki 5': Ka tiaki i te RNA, ā, ka āwhina i te tukanga whakamāori.
– Te tāpiritanga o te hiku poly-A: Ka whakapiki i te pumau o te RNA.
– Te Honohono: Te tango i ngā intron (ngā wāhanga kāore e whakakōwaetia ana) me te hono i ngā exon (ngā wāhanga whakakōwaetia).
He mea nui te honohono nā te mea ka taea te honohono rerekē, arā, ka taea e te ira kotahi te whakaputa i ngā momo pūmua rerekē. Mā tēnei ka nui te ngāwari o ngā pūtau ki te whakaputa i ngā momo pūmua me te kore e hiahiatia he maha o ngā ira. Ko te tikanga o tēnei, ehara i te mea ko te karihi anake te kaiwhakahaere mēnā he ira hohe engari ko tēhea putanga o te pūmua ka whakaputaina.
3. Te Kawe Whiriwhiri mā roto i ngā Pūwero Karihi
Kia pakari te RNA, me puta atu i te karihi ka tomo ki te cytoplasm kia whakamāoritia e ngā ribosome ki ngā pūmua. Mā ngā pūwero karihi ka taea anake te tomo, te puta atu rānei e ngā ngota tika.
Me tomo ētahi pūmua (pērā i ngā ira whakawhiti) ki roto i te karihi hei whakahaere i ngā ira. He tino whiriwhiri tēnei kawe, mā te whakamahi i ngā "tohu wāhitau" ngota pēnei i ngā tohu taunga karihi (NLS). Mā tēnei tikanga ka taea e te karihi te whakahaere i te rere o ngā mōhiohio me te whakarite kia tika te whakahaere.
Nucleolus: Te Whakahaere i te Hanga Ribosome me te Kaha Hanga Pūmua
Kei roto i te karihi te karihi, koinei te wāhi matua:
– te hanga rRNA (RNA ribosomal)
– Te huihuinga o ngā waeine ribosomal
He "wheketere pūmua" ngā ribosome. Nō reira, mā te whakahaere i te hanga ribosome, ka āwhina te karihi ki te whakatau i te tere o te hanga pūmua e te pūtau. Ina tipu, ina wehea kaha rānei te pūtau, he nui te karihi, ā, he tino kaha te mahi. I tetahi atu taha, i roto i ngā pūtau "mārie", ka heke pea te mahi a te karihi.
Te Tūranga o te Pūtau i roto i te Huringa me te Wehenga Pūtau
Ko te karihi te kaiwhakahaere o te huringa pūtau, arā, te raupapa o ngā wāhanga e tipu ai, e wehea ai hoki ngā pūtau. Ko tēnei whakahaere ko te whakaaturanga o ngā ira e whakahaere ana i ngā pūmua pērā i ngā cyclin me ngā CDK (ngā kinase e whakawhirinaki ana ki te cyclin). Mena ka pakaru te DNA, ka taea e te karihi te whakamutu i te huringa pūtau mō te wā poto kia wātea ai te wā hei whakatika.
I te wā o te wehenga pūtau (mitosis, meiosis rānei), ka tākaihia te DNA ki roto i ngā chromosome kia taea ai te tohatoha ōrite i waenga i ngā pūtau tamahine. He mahi tā te karihi i roto i:
– Te tāruaruatanga o te ira i mua i te wehenga
– Te whakapūpūtanga o te chromatin ki roto i ngā chromosome
– Te aroturuki i ngā hapa wehewehe ira
Ka taea e ngā hapa o tēnei tukanga te arahi ki ngā āhuatanga pēnei i te mate pukupuku (te wehenga kore mana whakahaere) me ngā mate ira nā te nui rawa o ngā ira.
Ngā Tikanga Whakatika DNA: Te Pupuri i te Pūmautanga Ira
He pūnaha whakatikatika DNA matatini anō hoki tō te karihi. Ka puta pea te kino o te DNA mai i te hihi UV, ngā matū, ngā hapa tāruarua rānei. Mēnā ka kitea he kino, ka whakahohehia e te karihi ngā ara whakatikatika pēnei i:
– Te whakatikatika i te takirua turanga (te whakatikatika tapahi turanga)
– Te whakatikatika i te nucleotide (te whakatikatika i te tango i te nucleotide)
– Te whakatikatika i ngā motu o ngā aho takirua
Ki te nui rawa te kino, ka taea e te karihi te whakaoho i te apoptosis, arā, te mate pūtau kua whakaritea. He rautaki tēnei hei ārai i ngā pūtau kua pakaru kei whanake hei pūtau kino.
Whakamutunga
Ko te karihi pūtau he whekau e mahi ana i ngā mahi nui: te penapena, te tiaki, me te whakahaere i te DNA, te puna o ngā mōhiohio ira. Ehara i te mea he "pūranga DNA" noa iho, he mahi nui tā te karihi ki te whakahaere i ngā mahi a te pūtau mā te whakahaere i te whakaaturanga ira, te tukatuka RNA, te whakahaere i te kawe o ngā ngota i roto i ngā pūwero karihi, me te hanganga o ngā ribosome i roto i te karihi. Hei tāpiri, ko te karihi te kaiwhakarite i te huringa pūtau, te whakarite i te wehenga pūtau tika, me te whakatika i ngā kino o te DNA hei pupuri i te pumau o te ira. Mā roto i ēnei tikanga katoa, ko te karihi te pokapū whakahaere, e whakatau ana me pēhea te tipu, te mahi, te urutau, me te ora o ngā pūtau.
Ki te hiahia koe, ka taea e au te tāpiri i tētahi whakaahua o te rere o te "DNA → RNA → pūmua", te hanga rānei i tētahi putanga māmā ake o te tuhinga mō te taumata kura tuarua/kura tuarua, i tētahi putanga pūtaiao ake rānei mō te taumata kāreti.
