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  • Every human being starts out the same way:

    每個人生命都有相同的開始:

  • two cells,

    分別來自父親和母親

  • one from each parent,

    的兩個細胞

  • found each other and became one.

    相遇並合而為一。

  • And that one cell reproduced itself,

    接著這個細胞複製自己,

  • dividing,

    分裂、

  • and dividing,

    分裂、

  • and dividing

    再分裂

  • until there were 10 trillion of them.

    直到達到十兆個細胞。

  • Do you realize there are more cells in one persons body

    你知道人身體細胞的數目

  • than there are stars in the Milky Way?

    比銀河裡的星星還多嗎?

  • But those 10 trillion cells are not just sitting there in a big pile.

    但這十兆個細胞不只是隨便堆成一堆。

  • That would make for a pretty boring human being!

    這樣的人類應該看起來很無趣吧!

  • So what is it that says a nose is a nose,

    那什麼決定鼻子要成為鼻子、

  • and toes is toes?

    腳趾成為腳趾呢?

  • What is it that says this is bone,

    什麼決定這個成為骨頭、

  • and this is brain,

    那個成為大腦、

  • and this is heart,

    那個成為心臟、

  • and this is that little thing in the back of your throat

    和那個在你喉嚨深處的東西—─

  • that you can never remember the name of?

    那個你一直記不起名稱的東西?

  • Everything that you are or ever will be made of

    任何組成你的部份

  • starts as a tiny link of instructions

    都來自一份小小的、

  • found in each and every cell.

    可在任何細胞中找到的說明書。

  • Every time your body wants to make something,

    每次你的身體想要建造什麼東西時,

  • it goes back to the instruction book,

    都會回去看這本說明書

  • looks it up, and puts it together.

    再進行建造。

  • So how does one cell hold all that information?

    那細胞是如何保存這些資訊呢?

  • Let's get small.

    讓它壓縮變小。

  • I mean, really small,

    我是說,非常小、

  • smaller than the tip of a sewing needle.

    比針尖還小。

  • Then we can take a journey inside a single cell

    如果我們能走進細胞

  • to find out what makes up the book of you,

    去探究這本書的組成,

  • your genome.

    我們會發現:你的基因體。

  • The first thing we see is that the whole genome,

    首先我們要瞭解基因體,

  • all your DNA,

    也就是你所有的DNA,

  • is contained inside its own tiny compartment

    是被存放在一個叫做細胞核

  • called the nucleus.

    的小地方。

  • If we stretched out all the DNA in this one cell

    如果我們把一個細胞的 DNA 拉直

  • into a single thread,

    成一條線,

  • it would be over 3 feet long!

    這條線會超過 3 英尺(約 91 公分)!

  • We have to make it fit in a tiny compartment

    我們比須把它局限在一個

  • that is a million times smaller.

    僅百萬分之一倍的小空間。

  • We could just bunch it up like Christmas lights,

    我們可以把它亂捲一通,像聖誔燈一般,

  • but that can get messy.

    但這樣就太凌亂了。

  • We need some organization.

    我們需要一些整理方法。

  • First, the long thread of DNA wraps around proteins

    首先,線狀的 DNA 會纏繞一些蛋白質

  • clustered into little beads called nucleosomes,

    變成稱為核小體的小珠子,

  • which end up looking like a long, beaded necklace.

    它會看起來像是一條長長的串珠項鏈。

  • And that necklace is wrapped up in its own spiral

    接著,這條項鏈會繞成

  • like an old telephone cord.

    像是電話線一樣的螺旋。

  • And those spirals get layered on top of one another

    再來,這些螺旋會相互交疊

  • until we get a neat little shape that fits inside the nucleus.

    直到可以整齊地放進細胞核中。

  • Waaah! Three feet of DNA squeezed into a tiny compartment.

    哇!3 英尺的DNA就這樣擠進小小的空間。

  • If only we could hire DNA to pack our suitcases!

    真希望我們可以用相同的機制打包行李!

  • Each tiny mass of DNA is called a chromosome.

    每一小團 DNA 被成為染色體。

  • The book of you would have 46 chapters,

    在這本說明書中有 46 章

  • one for each chromosome.

    每一章就是一條染色體。

  • 23 chapters of your book came from your mom,

    說明書的其中 23 章來自你的母親,

  • and 23 chapters came from your dad.

    另外則來自你的父親。

  • Two of those chapters, called "X" and "Y",

    其中被稱為 X 和 Y 的兩章,

  • determine if you are male, "XY",

    會決定你是男生,也就是 XY;

  • or female, "XX".

    或是女生,也就是 XX。

  • Put them together and we get two almost identical

    它們會組成兩套幾乎相同

  • but slightly different sets of 23 chapters.

    卻又有些微差異的23章。

  • The tiny variations are what makes each person different.

    這些微差異就造成了人與人之間的不同。

  • It's estimated that all the chapters together

    如果把所有的章節都列入計算

  • hold about 20,000 individual instructions, called genes.

    大約會有兩萬筆說明,也就是基因。

  • Written out, all those 20,000 instructions

    如果把這兩萬筆說明全部寫下來

  • are 30 million letters long!

    會長達三千萬個字母!

  • If someone were writing one letter per second,

    如果人可以一秒鐘寫一個字母,

  • it would take them almost an entire year to write it once.

    那也需要花將近一年才能寫完一次。

  • It turns out that our genome book is much, much longer

    然而,我們的說明書比

  • than just those 30 million letters,

    三千萬個字母還長出許多—

  • almost 100 times longer!

    將近是它的一百倍!

  • What are all those extra pages for?

    那這些多餘的書頁又寫了些什麼呢?

  • Well, each page of instructions has a few pages of nonsense inserted

    嗯,每部份的說明都會插入幾頁無意義的編碼。

  • that have to be taken out before we end up with something useful.

    我們必須先將這些亂碼移除才能看到有意義的資訊。

  • The parts we throw out, we call introns.

    這部份我們移除的亂碼被稱為內插子。

  • The instructions we keep, we call exons.

    而保留下來的資訊被稱為外顯子。

  • We can also have hundreds of pages in between each gene.

    我們的基因與基因之間也可能有幾百頁的亂碼。

  • Some of these excess pages were inserted

    有些是在我們的祖先被病毒感染時

  • by nasty little infections in our ancestors,

    所插入的多餘頁面。

  • but some of them are actually helpful.

    但也有些看似無意的頁面是有用的。

  • They protect the ends of each chapter from being damaged,

    它們可以保護章節的頭尾免於破壞,

  • or some help our cells find a particular thing they are looking for,

    或當作索引,

  • or give a cell a signal to stop making something.

    也有可能是當作停止製造的訊號。

  • All in all, for every page of instructions

    總而言之,在每部份說明中

  • there is almost 100 pages of filler.

    大約包含了一百頁的內容。

  • In the end, each of our books' 46 chapters

    最後,我們書的 46 章

  • is between 48 and 250 million letters long.

    會介於 4.8 千萬到 2.5 億個字母長。

  • That's 3.2 billion letters total!

    共計三十二億個字母!

  • To type all that copy, you would be at it for over 100 years,

    若以打字方式複製,你需要花上一百年,

  • and the book would be over 600,000 pages long.

    而且這本書會超過六十萬頁。

  • Every type of cell carries the same book,

    每一種細胞都帶有相同的說明書,

  • but each has a set of bookmarks that tell it exactly

    但是會有不同的索引幫助搜尋

  • which pages it needs to look up.

    它們需要看的頁面。

  • So a bone cell reads only the set of instructions it needs to become bone.

    所以骨細胞只會看和生成骨頭相關的指引。

  • Your brain cells,

    你的腦細胞

  • they read the set that tells them how to become brain.

    會閱讀組成大腦所需的部份。

  • If some cells suddenly decide to start reading other instructions,

    如果一個細胞突然開始閱讀其他的指引

  • they can actually change from one type to another.

    他們就可以從一種細胞轉換成另一種。

  • So every little cell in your body is holding on to an amazing book,

    你身體裡每一個細胞都帶著這本神奇的書,

  • full of the instructions for life.

    這本書充滿對生命所有的註解。

  • Your nose reads nose pages,

    你的鼻子閱讀關於鼻子的部份,

  • your toes read toes pages,

    你的腳趾則閱讀關於腳趾的部份,

  • and that little thing in the back of your throat,

    而你喉嚨深處的那個小東西

  • it's got its own pages too.

    也有屬於自己的章節。

  • They are under uvula.

    就是標示「懸雍垂」的那幾頁。

Every human being starts out the same way:

每個人生命都有相同的開始:

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B1 中級 中文 TED-Ed 細胞 字母 腳趾 章節 鼻子

【TED-Ed】關於你的DNA (DNA: The book of you - Joe Hanson)

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    VoiceTube 發佈於 2013 年 05 月 06 日
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