無病無痛,沒有任何交通或人為意外的話,人類是否會進入不死永生狀態呢?633Please respect copyright.PENANAcuoCQq7uBs
633Please respect copyright.PENANA0AxsG23LJJ
答案是,不會。633Please respect copyright.PENANACSSWEbnCvd
633Please respect copyright.PENANAGDpLQmkqbQ
箇中的原因,就是在於染色體亦即是DNA的運作機制之上。633Please respect copyright.PENANAAy9P5e4So7
633Please respect copyright.PENANAbm0YCDKbTx
633Please respect copyright.PENANA9V2aqdLgLL
(圖1)正常人體細胞分裂的時候,染色體的長度會越來越短。633Please respect copyright.PENANAxBqTxqQUwe633Please respect copyright.PENANALuJfyMgQr9
633Please respect copyright.PENANAgQYDwQUs77
633Please respect copyright.PENANAcX73Ku0IOY
(圖2)染色體的頂端區域,我們稱之為Telomere。正常細胞分裂後,Telomere的長度便會越來越短,所以導致染色體的總長度亦會有所減少。633Please respect copyright.PENANAiSAallWlRG633Please respect copyright.PENANA2AgMjMsWQi
633Please respect copyright.PENANAHSy4KIWehh
(圖3)而幹細胞進行分裂的時候,則會有著Telomerase的協助,導致Telomere的長度便並不會有所減少。633Please respect copyright.PENANAovqqP11nef
然而,當幹細胞變成正常細胞後,Telomerase的功能便會消失。633Please respect copyright.PENANAoJJnCtwpkf633Please respect copyright.PENANAlmXUhcFY6e
633Please respect copyright.PENANAnLaDrqBKJ2
633Please respect copyright.PENANAH1T7H7lOHI
(圖4)當Telomere長度削減到一定程度的時候,細胞便會自行啟動機制滅亡,又或者陷入衰老(Senescence)狀態。633Please respect copyright.PENANAM3gVvCw8PI
633Please respect copyright.PENANAPOwTXJmS4U
細胞滅亡或衰老的話,器官的功能便會衰退,最後亦會支撐不住,無法正常運作,促成死亡。633Please respect copyright.PENANAKIKejvGZgw633Please respect copyright.PENANAGXtDeb3F2w
633Please respect copyright.PENANAQuz1HlDSNv
你可能會問,現在科技如此倡明,那麼我們只要學習幹細胞的那一套方式,動用外力重啟Telomerase功能,那不就能踏入永生嗎?633Please respect copyright.PENANArn254FTBvj
633Please respect copyright.PENANAMZrLO7X5Kv
這個思路並沒有錯,只不過代價就是會增加患癌的風險。633Please respect copyright.PENANA4qhpIpAqZb
633Please respect copyright.PENANAhMRrCFDQPQ
事實上,不少癌細胞的特徵就是Telomere長度非常之短,但又有著一定水平的Telomerase功能穩定維持著Telomere的長度,逃避進入滅亡的命運。633Please respect copyright.PENANA5msgPsSU7O
633Please respect copyright.PENANAxohCYFiDji
另一方面的想,如果細胞真的是踏入「永生」狀態的話,終有一天無可避免會累積各種的DNA變異,促成癌細胞的誕生。633Please respect copyright.PENANAh7RjSIFBAe
633Please respect copyright.PENANA5ERoOuyaEy
(圖5)既然Telomere對細胞的壽命有著重要影響的話,那麼一些較為長壽的物種是否擁有較長的Telomere呢?633Please respect copyright.PENANA8BGpjdlw9R
633Please respect copyright.PENANAy9gqYYQ7C7
科學家比較各物種的Telomere後(Ref1),發現海豚的起始Telomere長度比人類高出6倍以上,但壽命長度始終是人類佔優。633Please respect copyright.PENANA9FcG9r8sXq633Please respect copyright.PENANAgriJA3QlpG
633Please respect copyright.PENANAnzpc56lecY
反而,決定物種壽命長度的其中一種因素,則是Telomere衰減的速度;633Please respect copyright.PENANAiuSBRC13Iw
Telomere衰減的速度只是一個參考性的指標,並非絕對。物種的大小、新陳代謝機制的不同等等均會對壽命長度有著影響。633Please respect copyright.PENANAWACTEqN6DT
633Please respect copyright.PENANAYuu0aw76st
人類每年約會減少71單位Telomere的長度,最高壽命為120歲。633Please respect copyright.PENANA9WODSC0et5
而老鼠每年會減少7000單位Telomere長度,最高壽命為5歲。633Please respect copyright.PENANAeW5gxM2bxp
633Please respect copyright.PENANAOmB7iKOSqq
人類:每年減少71;120歲633Please respect copyright.PENANAfWqMQ0SYwj
大象:每年減少109;66歲633Please respect copyright.PENANAW6DnTnecx2
紅鸛:每年減少105;60歲633Please respect copyright.PENANAOmbmc2C8OG
海豚:每年減少766;52歲633Please respect copyright.PENANAo7qVCKiby4
兀鷲:每年減少209;41歲633Please respect copyright.PENANADos49f1ZJC
海鷗:每年減少771;25歲633Please respect copyright.PENANAxbwC2xkVS5
馴鹿:每年減少531;22歲633Please respect copyright.PENANAThvooqFMTw
山羊:每年減少363;21歲633Please respect copyright.PENANAzNGHOjov8T
老鼠:每年減少7000;5歲633Please respect copyright.PENANASi1axQsJ6a
633Please respect copyright.PENANAmFdMUofo0x
633Please respect copyright.PENANA8YPTZkg3Kd
龜又是每年減少幾多呢?有待有心人發掘。633Please respect copyright.PENANARvYc949Rfz
633Please respect copyright.PENANAov1cY5xtjj
633Please respect copyright.PENANALMuV2TphTV
如果想我快啲出文的話,請入去Penana網站科普專欄–薯不揀單俾一個like以及Bookmark,這對我非常之重要。633Please respect copyright.PENANANi64L49RBt
633Please respect copyright.PENANAV48al7hICr
Link: https://www.penana.com/story/66244/%E7%A7%91%E6%99%AE%E5%B0%88%E6%AC%84-%E8%96%AF%E4%B8%8D%E6%8F%80%E5%96%AE/toc633Please respect copyright.PENANAwIhqU4MM9M
633Please respect copyright.PENANAFJ5fSjtAj5
同時亦可以在Penana網站裡按「買一嚿/半嚿薯仔」,以課金的方式推動我繼續搜羅資料寫文,多謝。633Please respect copyright.PENANAq9OY5y1jAc
633Please respect copyright.PENANAYj9hDqy40N
Link:633Please respect copyright.PENANALoaFOFBI96
https://www.penana.com/user/27349/%E8%96%AF%E4%BB%94%E8%81%9E%E8%8C%B1%E8%8E%89/portfolio633Please respect copyright.PENANAAMZsXT2KWl
633Please respect copyright.PENANAAwfdRnJMvB
633Please respect copyright.PENANAbEecMzrXaQ
有興趣接收科學資訊的話,歡迎follow IG: potatopigtongue。633Please respect copyright.PENANAXxA3mMSuPx
633Please respect copyright.PENANAUDEhGtAwhZ
633Please respect copyright.PENANAehWCPS1Te7
Ref1:https://www.pnas.org/content/116/30/15122633Please respect copyright.PENANAoaqaGSUPyC