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？768Please respect copyright.ＰＥＮＡＮＡa6fYb2LArf
768Please respect copyright.ＰＥＮＡＮＡUmPinnEo7U
答案是，不會。768Please respect copyright.ＰＥＮＡＮＡvgPFNnybmk
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箇中的原因，就是在於染色體亦即是DNA的運作機制之上。768Please respect copyright.ＰＥＮＡＮＡXWMRwocJbr
768Please respect copyright.ＰＥＮＡＮＡpby5VbaGdO
768Please respect copyright.ＰＥＮＡＮＡkCfcxeX4OB
（圖1）正常人體細胞分裂的時候，染色體的長度會越來越短。768Please respect copyright.ＰＥＮＡＮＡwFTMkT0Wul
768Please respect copyright.ＰＥＮＡＮＡIvxdhalV9w
768Please respect copyright.ＰＥＮＡＮＡG0SXtEHzn6
768Please respect copyright.ＰＥＮＡＮＡu3CflpLWcR
（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。768Please respect copyright.ＰＥＮＡＮＡY8Ukn6z0Dl
768Please respect copyright.ＰＥＮＡＮＡMvp2u3ytnP
768Please respect copyright.ＰＥＮＡＮＡehmEc14wRL
（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。768Please respect copyright.ＰＥＮＡＮＡeEkGDnR2BV
然而，當幹細胞變成正常細胞後，Telomerase的功能便會消失。768Please respect copyright.ＰＥＮＡＮＡAHpx8EWNTz
768Please respect copyright.ＰＥＮＡＮＡQ9lVZXW4dv
768Please respect copyright.ＰＥＮＡＮＡD42mSB5QyX
768Please respect copyright.ＰＥＮＡＮＡejSuLEfgC3
（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。768Please respect copyright.ＰＥＮＡＮＡCfwaLVYzFd
768Please respect copyright.ＰＥＮＡＮＡj02foLvPib
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。768Please respect copyright.ＰＥＮＡＮＡJqLELvj6Iq
768Please respect copyright.ＰＥＮＡＮＡcSp8HrG3Tw
768Please respect copyright.ＰＥＮＡＮＡChatTtvtZx
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？768Please respect copyright.ＰＥＮＡＮＡl0GfMHwnJg
768Please respect copyright.ＰＥＮＡＮＡM4Ggnf5MLg
這個思路並沒有錯，只不過代價就是會增加患癌的風險。768Please respect copyright.ＰＥＮＡＮＡV0Vq6AMmgE
768Please respect copyright.ＰＥＮＡＮＡmHAyRubisV
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。768Please respect copyright.ＰＥＮＡＮＡMyYlJfFtgb
768Please respect copyright.ＰＥＮＡＮＡcaphAcLLGL
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。768Please respect copyright.ＰＥＮＡＮＡtXcImfPFrS
768Please respect copyright.ＰＥＮＡＮＡO1ehXXSIzj
（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？768Please respect copyright.ＰＥＮＡＮＡeSdkhbOr9j
768Please respect copyright.ＰＥＮＡＮＡvsyMP1WNQE
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。768Please respect copyright.ＰＥＮＡＮＡO8dyhF4LLh
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768Please respect copyright.ＰＥＮＡＮＡHw53wc46T5
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；768Please respect copyright.ＰＥＮＡＮＡQgAGFWKjT1
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。768Please respect copyright.ＰＥＮＡＮＡhHCi0qBWAE
768Please respect copyright.ＰＥＮＡＮＡEpeB8EyCWO
人類每年約會減少71單位Telomere的長度，最高壽命為120歲。768Please respect copyright.ＰＥＮＡＮＡzDlXwJmBNW
而老鼠每年會減少7000單位Telomere長度，最高壽命為5歲。768Please respect copyright.ＰＥＮＡＮＡV9GsJCcjLn
768Please respect copyright.ＰＥＮＡＮＡUsVEFtRSI5
人類：每年減少71；120歲768Please respect copyright.ＰＥＮＡＮＡMvIp3e39aO
大象：每年減少109；66歲768Please respect copyright.ＰＥＮＡＮＡpHpGeUfNKw
紅鸛：每年減少105；60歲768Please respect copyright.ＰＥＮＡＮＡ1b1IiyuMDn
海豚：每年減少766；52歲768Please respect copyright.ＰＥＮＡＮＡ4SO5NxrLsM
兀鷲：每年減少209；41歲768Please respect copyright.ＰＥＮＡＮＡXCXsrih1QD
海鷗：每年減少771；25歲768Please respect copyright.ＰＥＮＡＮＡamZU3DaGBJ
馴鹿：每年減少531；22歲768Please respect copyright.ＰＥＮＡＮＡ5H3aVqQg74
山羊：每年減少363；21歲768Please respect copyright.ＰＥＮＡＮＡ3Q7F7tBsmw
老鼠：每年減少7000；5歲768Please respect copyright.ＰＥＮＡＮＡjdOLpozniw
768Please respect copyright.ＰＥＮＡＮＡ9Fmp7YxEsN
768Please respect copyright.ＰＥＮＡＮＡPjr2CxUhw2
龜又是每年減少幾多呢？有待有心人發掘。768Please respect copyright.ＰＥＮＡＮＡfwhda60nh6
768Please respect copyright.ＰＥＮＡＮＡIbtULx87MV
768Please respect copyright.ＰＥＮＡＮＡDRxjwHnUBa
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。768Please respect copyright.ＰＥＮＡＮＡ5isVoZAYMT
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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/toc768Please respect copyright.ＰＥＮＡＮＡUpsxxZA197
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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。768Please respect copyright.ＰＥＮＡＮＡ9cXK4EQncO
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Link:768Please respect copyright.ＰＥＮＡＮＡ8wiw4yKh83
https://www.penana.com/user/27349/%E8%96%AF%E4%BB%94%E8%81%9E%E8%8C%B1%E8%8E%89/portfolio768Please respect copyright.ＰＥＮＡＮＡXQjchs0A61
768Please respect copyright.ＰＥＮＡＮＡctQ0ME0xqh
768Please respect copyright.ＰＥＮＡＮＡ4TicTL65oe
有興趣接收科學資訊的話，歡迎follow IG: potatopigtongue。768Please respect copyright.ＰＥＮＡＮＡqLXy9HNYOM
768Please respect copyright.ＰＥＮＡＮＡLJyHl38krr
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Ref1:https://www.pnas.org/content/116/30/15122768Please respect copyright.ＰＥＮＡＮＡy6f04QBsFr
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