Name: 舊的和奇怪的。Archaea, Bacteria & Protists - CrashCourse Biology #35 (Old & Odd: Archaea, Bacteria & Protists - CrashCourse Biology #35)
Uploaded: 2021-01-14T05:39:26.000Z
Duration: 12 min 17 s

We've spent the past few months talking about animals

在過去的數星期的Crash Couse中我們都在談論動物

here on Crash Course, specifically human animals, because...

尤其是人類這種動物，因為.....

well, because humans... we love talking about ourselves,

and also because animals are just really interesting.

But it's high time that we talked about the rest of the living world.

但是現在是該我們討論世界上其他動物的時候了

Because I hate to break it to ya, but most of the alive things on

我不太想要粉碎你的想像，但事實上地球上大多數的生物

And by "most of the alive things" I mean that these organisms

關於大多數生物這點，我是指這些生物

make up two of the three taxonomic domains of all life,

I'm talking about archaea, bacteria and protists.

我指的是古菌、細菌、以及原生生物

With the exception of a few protists, they're all unicellular,

除了少數的原生生物之外，上述生物都是單細胞生物

and they are, by far, the most abundant and diverse organisms on Earth.

而且這些生物，就目前所知，是地球上最繁盛且最多樣的生物

More important, they lay claim to the world's oldest

最重要的是，這些生物有著世界上最古老

and earliest living lineages, dating back to the very first twinkle of life on this planet.

且最早期的血統，可以追溯至這星球的生命起源

因此藉由了解這三個域中的生物

you begin to truly understand life on earth, its origins,

你將真正地了解地球上的生命、它的起源

and how everything that came after them, including us, came to be.

以及世間萬物是如何接替出現 － 這也包括了我們

What's more, because their heritage is so ancient,

不僅如此，因為這些生物是如此古老

these organisms often take weird, cool forms

that don't look like life as we think about it,

它們與我們熟知的生物大庭相逕

Some not only live but thrive in environments that would kill you, me, and everything we hold dear.

它們之中有些棲息在你我以及我們熟知的一切都無法生存的嚴酷的環境中

And others make their living by invading organisms,

Then there are those that do the opposite, making life possible by,

還有一部分則使用相反的作法，它們的生存是依靠

fixing nitrogen from the atmosphere and helping animals digest food.

將大氣中的氮氣固定(轉化成含氮化合物)或者協助其他動物消化食物

Members of these groups have names like Sailor's Eyeballs

這些族群中的成員大多數都有著像是"水手的眼球"

and Dog Vomit Slime Mold, and they can take the shape of rods, blobs, corkscrews or coils.

以及"狗嘔吐物似的黏菌"的俗稱，同時他們也具有多種形狀，像是桿狀、泡泡狀、螺旋狀、或是捲曲狀

Kinda like the doddering, eccentric relatives

有點像老態龍鍾、行為怪異的親戚

you're forced to spend some holiday with once a year,

但你每年逢年過節卻還是得要跟它們見一次面。

the archaea, bacteria and protists are our oldest, oddest relatives.

古菌、細菌以及原生生物是我們最老、最怪異的的親戚們

And it's about time you got to know them.

現在正是你好好了解它們的時候

There's no denying it: Every multicellular organism on this planet,

無可否認的是：這星球上所有的多細胞生物

whether it be a mushroom or a vampire bat,

And while some of these single celled organisms evolved to populate

雖然部分的單細胞生物演化成了犀牛或者榕樹

the world as rhinos and strangler figs, others found happiness in the unicellular lifestyle,

並棲息在世界各地，剩下的傢伙們仍然很享受它們的單細胞生活

and they haven't changed much in the past few billion years.

並且它們在過去的數百萬年間都沒有什麼改變

Today, nearly all unicellular organisms are either archaea, bacteria or protists.

直至今日，幾乎所有的單細胞生物都是古菌、細菌或原生生物

Protists, you'll recall, are eukaryotic organisms

如果你還記得的話，原生生物屬於真核生物

that make up the kingdom Protista under the domain Eukarya.

原生生物界位在真核生物域的底下

Bacteria and Archaea, meanwhile, are their own prokaryotic domains.

細菌以及古菌，都屬於原核生物並各成一域

And I hope you haven't forgotten this, the big difference

between prokaryotes and eukaryotes is that eukaryotic organisms,

原核生物以及真核生物之間有很大的不同

including you and the plants, and fungi and animals that you know,

真核生物包括你、你熟知的植物、真菌以及動物

have cells with a nucleus that hold their genetic information,

都具有細胞核，並把基因訊息都儲存在細胞核中

while prokaryotic cells don't have a nucleus or any organelles to speak of.

而原核生物則沒有細胞核和膜狀胞器

These two groups do have some important things in common,

like having plasma membranes that are filled with cytoplasm,

像是都具有細胞膜，膜裡面充滿著細胞質

and ribosomes that contain RNA and synthesize proteins.

以及具有包含著RNA並負責製造蛋白質的核醣體

And they both have DNA that carries the instructions for operating the cell.

而且這兩個類群都具有DNA，調控著整個細胞的生理運作

But eukaryotic DNA comes in strands in the form of chromosomes,

但真核生物的DNA會束在一起，纏繞成為染色體

while prokaryotic DNA is found in rings called plasmids.

而原核生物的DNA則為在環狀的質體上 (實際上是散落在細胞質中，質體只是一部分DNA)

再來整理一次，這次要放入感情：

Protists are mostly single-celled eukaryotic organisms.

原生生物大多數是單細胞的真核生物

Archaea and bacteria are single-celled prokaryotic organisms.

古菌以及細菌是單細胞的原核生物

The word "prokaryote" actually means before the nucleus,

which is a clue that prokaryotes are an older form of life.

這暗示著原核生物的起源更為古早

And we literally cannot find anything older than Archaea.

我們也確實沒發現有比古菌更早的生物

The first Archaea fossils date back 3.5 billion years ago

最早的古菌化石可以追朔到三十五億年前

I'm talking just a billion years after the Earth formed

而這只是地球形成的十億年之後

and was still bombarded by comets and meteors,

當時仍受到小行星以及隕石的轟炸

But in the midst of all that, archaea were just chillaxing.

而在這樣的環境中，古菌卻是怡然自得

Earth's climate has calmed down since then, so today

之後，地球的環境逐漸冷卻穩定，到了今天

archaea are found in some of the world's most extreme environments:

古菌僅生存於地球上最極端的環境中

In underwater hydrothermal vents, oil wells, volcanic hot springs,

例如海底熱泉、石油井、火山熱泉

Archaea were probably the earliest living things,

and their adaptability is probably what allowed them

to take root in Earth's early, kind of grody environment.

於地球早期生存，當時的環境較為惡劣

One key group of the archaea are the methanogens.

古菌中的一大類別是甲烷生成菌

These guys prefer more moderate environments, like mud,

這些傢伙偏好相較溫和的環境，像是泥地、

swamps and your intestines, but they derive their energy from hydrogen gas and carbon dioxide,

沼澤以及你的腸道。它們利用氫氣和二氧化碳來獲得能量

which is pretty cool and they emit methane as their waste product.

這相當特別，另外在這過程中它們會排出副產物甲烷

We know that waste as swamp gas, and also, other kinds of gas.

我們都知道那個副產物甲烷就是沼氣，同時也可以算是瓦斯

The other groups are extremophiles, which not only tolerate

另一個類別是嗜極端菌，它們不僅是忍耐力超強

而是根本就喜歡住在險惡的環境中

The most famous of these are the thermophiles,

which live in temperatures that would melt your face off.

他生活的環境溫度可以融掉你的臉

I mean, serious: Pyrolobus fumarii, a species of archaea

我沒在開玩笑，Pyrolobus fumarii 是古菌的一種，

discovered in the late 1990's in a hydrothermal vent,

live at temperatures around 113 degrees celsius.

Significantly above the boiling point of water!

Most organisms can't take heat like that,

大多數的生物根本無法忍受這樣的高溫

because it causes their DNA to unwind and their proteins to denature

因為這會使得生物的DNA解旋，並使得蛋白質變性

But thermophiles have evolved adaptations that keep them stable

但嗜熱菌演化出了適應方式來保持DNA和蛋白質的穩定

There are also halophiles, or salt lovers, which live in places

另外還有所謂的嗜鹽菌，或稱鹽類偏好生物，它們住在

like the Dead Sea or the Great Salt Lake, and probably Daniel Tosh's mouth.

像是死海或者大鹽湖之類的地方，又或者是Daniel Tosh的嘴中

Most halophiles breathe oxygen and are heterotrophic,

多數的嗜鹽菌呼吸氧氣並且是異營生物

but there are some bizarro outliers, like species that use sunlight

但總有特例，像是有些種類會利用陽光

來產生能量，但用的方式卻跟植物不同

they have light-harvesting pigments in their membranes

它們的細胞膜上具有能吸收光的色素

that react with light and enable the cell to make ATP for energy.

可以與光進行反應使得細胞能獲得ATP作為能量