ADM-201 dump PMP dumps pdf SSCP exam materials CBAP exam sample questions

神奇的分子机器 – 译学馆
未登录,请登录后再发表信息
最新评论 (0)
播放视频

神奇的分子机器

Your Amazing Molecular Machines

这些是微型分子机器
These are tiny molecular machines,
它们正在你的体内运作着
and they are doing this inside your body right now.
想知道它们如何运作 我们需要从宏观上看
To understand why, we have to zoom out.
每天 在一个成年人体内
Every day, in an adult human body,
五百亿至七百亿的细胞凋亡
50 to 70 billion of your cells die.
它们有可能受调控 被破坏 或仅仅是衰老了
Either they’re stressed, or damaged, or just old.
但这都很正常 事实上 这叫做细胞编程性死亡
But this is normal – in fact, it’s called”programmed cell death”.
但是 为了补充这些失去的细胞
But, to make up for all these lost cells,
现在 数10亿的细胞正在分裂
right now, billions of your cells are dividing,
本质上就是制造新细胞
essentially creating new cells.
而细胞分裂的这一过程 也被成为有丝分裂
And that process of cell division, also called mitosis.
这一过程需要非常多的分子机器
Well, it requires an army of tiny molecular machines.
让我们近距离观察
So, let’s take a closer look.
DNA是一个开始观察的好起点
DNA is a good place to start –
就是我们经常提到的螺旋状大分子
the double helix molecule we always talk about.
这是对DNA十分精确的描述
This is a scientifically accurate depiction of DNA,
由德鲁· 贝里创造
created by Drew Berry
他来自沃尔特和伊丽莎霍尔医学研究所
at the Walter and Eliza Hall Institute of Medical Research.
如果你解开这两条链
If you unwind the two strands,
你可以看到两边都有糖-磷酸骨架
you can see that each has a sugar-phosphate backbone
连接着按顺序排列好的核酸碱基对
connected to the sequence of nucleic acid base pairs,
即A T G和C碱基
known by the letters A, T, G and C.
现在 将两条链反过来
Now, the strands run in opposite directions,
这对DNA复制十分重要
which is important when you go to copy DNA.
复制DNA是细胞分裂的第一步
Copying DNA is one of the first steps in cell division.
现在DNA的两条链被蓝色迷你分子机器
Here, the two strands of DNA are being unwound and separated
——解旋酶解开并分离
by the tiny blue molecular machine called”helicase”.
解旋酶旋转得就跟飞机引擎一样快
Helicase literally spins as fast as a jet engine!
DNA的右链在接连不断地与游离的核苷酸配对组合
The strand of DNA on the right has its complementary strand assembled continuously.
但是另一条链更复杂
But the other strand is more complicated,
因为它是反向复制的
because it runs in the opposite direction.
因此它必须倒过来以环的形式来进行配对组合
So it must be looped out with its complementary strand assembled
一部分一部分地结合
in reverse, section by section.
最终 你会得到两个完全一样的DNA分子
At the end of this process, you have two identical DNA molecules,
每一条都有几厘米长
each one a few centimeters long,
但只有几毫微米宽
but just a couple nanometers wide.
因此 为了避免DNA分子打结混乱
So, to prevent the DNA from becoming a tangled mess,
它会被组织蛋白包裹
it is wrapped around proteins called”histones”,
形成核小体
forming a nucleosome.
这些核小体接连在一起就形成了核染色质
These nucleosomes are bundled together into a fiber known as chromatin,
染色质再螺旋在一起就形成了染色体
which is further looped and coiled to form a chromosome,
——人体中大分子的一种
one of the largest molecular structures in your body.
你可以在显微镜下清晰地看见处于分裂期的细胞中的染色体
You can actually see chromosomes under a microscope in dividing cells.
只有在分裂期它们才会形成特定的形状
Only then do they take on their characteristic shape.
此外 DNA分子在细胞核中会更加散乱
Otherwise, the DNA is more strewn inside the nucleus.
对于哺乳动物 细胞分裂一次需要一小时
The process of dividing a cell takes around an hour in mammals,
因此这一镜头是经过加速的
so this footage is from a time-lapse.
可以看到 染色体是如何在细胞赤道板上排列成一条线的
You can see how the chromosomes line up on the equator of the cell.
现在 一切顺利进行
Now, when everything is right,
它们就会分裂成两个新的子细胞
they are pulled apart into the two new daughter cells,
每个子细胞都有着一样的DNA
each one containing an identical copy of DNA.
就像看上去那样
Now, simple as this looks,
这一过程十分复杂并且需要
the process is incredibly complicated and requires
非常多令人惊叹的微型机器来完成
even more fascinating molecular machines to accomplish it.
让我们来观察一个染色体
So, let’s look at a single chromosome.
一个染色体由两个香肠状的染色单体组成
One chromosome consists of two sausage shaped chromatids,
包含着先前复制的DNA分子
containing the identical copies of DNA made earlier.
每个染色单体都被微管纤维连接着
Each chromatid is attached to microtubule fibers,
这些纤维会引导并帮助它们正确地排成一列
which guide and help align them in the correct position.
这些纤维在着丝粒处与染色单体连接 即被标记为红色的部分
The microtubules are connected to the chromatid at the kinetochore, here colored red.
着丝粒由上百种蛋白质组成
The kinetochore consists of hundreds of different proteins
这些蛋白一起运转以达成多种目的
working together to achieve multiple objectives.
事实上 它是人体中最精细的化学结构之一
In fact, it’s one of the most sophisticated molecular mechanisms inside your body.
着丝粒对染色体的成功分裂至关重要
The kinetochore is central to the successful separation of the chromatids.
它使染色体与微管形成一个动态的连接
It creates a dynamic connection between the chromosome and the microtubules.
这一动态连接的原因尚未有人找出
For a reason no one’s yet been able to figure out,
即着丝粒是如何瞬间形成
the microtubules are constantly being built at one end
并在下一秒又拆解消失
and deconstructed at the other.
当染色体还没有准备好时 着丝粒
While the chromosome is still getting ready, the kinetochore
会给细胞剩余部分发出“停止”的信号
sends out a chemical “stop” signal to the rest of the cell,
这里用红色分子表示
shown here by the red molecules,
通俗来讲 就是“染色体还没准备好分裂”
basically saying,”this chromosome is not yet ready to divide.”
着丝粒在物理上也非常的敏感
The kinetochore also mechanically senses tension.
当分裂的时机到了
When the tension is just right,
染色体的位置和着丝都很完美
and the position and attachment are correct,
所有蛋白都准备好时 这里表示为变绿
all the proteins get ready, shown here by turning green.
在这个时候 停止信号传播系统仍未被关掉!
At this point, the stop signal broadcasting system is not switched off!
反而 它从着丝粒被运走
Instead, it is literally carried away
运出染色体
from the kinetochore, down the microtubules,
由动力蛋白运输——那个走着路的家伙
by a dynein motor – that’s the walking guy.
就像它看起来的样子:
This is really what it looks like:
它有着长长的“腿” 因此它可以跨过障碍并越过驱动蛋白
it has long”legs” so it can avoid obstacles and step over the kinesins,
即反方向行走的分子引擎
molecular motors that walk in the opposite direction.
就自身而言 我真的被这些迷你分子机器所震惊
Personally, I’m astounded by these tiny molecular machines,
它们怎么做到在这一瞬间 在人体里
how they’re able to routinely and faithfully execute their functions billions of times
规律地 忠诚地执行它们的职能上百万次
over inside your body at this exact instant.
我同时也被
I’m also amazed
那些能够弄懂其中机制的科学家们所折服
by the scientists who were able to work out how this happens
这使我们能做出如此真实的描述
in such detail that we could create realistic depictions of them,
就像你在这个视频中看到的动画那样
like you saw in the animations in this video.
但最令人惊叹的事情
But, perhaps, the most amazing thing is
应该还未被发现 比如解决
just how much is left to be discovered, like figuring out
染色单体是如何精确地被引导到细胞两极的问题
how exactly the chromatids are pulled to opposite ends of the cell.
还有很多问题我们都尚未解决
There is still so much that we don’t quite know.
你们都知道 那些在科幻小说中
You know, what I find exciting is,
令人激动的事情 在这几十年里
that in science fiction, for decades,
我们写过将微型纳米机器人注射进入
we’ve been writing about tiny nanobots that will be injected
血液循环系统中来治疗人体
into our blood streams that can heal us.
但 这也同时说明了
But, what this suggests,
在我们人体内部的微型分子机器的存在
the existence of these tiny molecular machines inside us,
证明了不是物理屏障阻止了分子机器的应用
it suggests that there isn’t a physical limit that would prevent that.
因此 我觉得在未来很有可能
And so, I think it’s pretty likely that, in future,
我们会研发出自己的微型分子机器
we will be able to develop our own tiny molecular machines
这些机器会比身体自己更好地修复我们的身体
that will be able to repair our bodies better than they can repair themselves.

发表评论

译制信息
视频概述

神奇的分子机器

听录译者

收集自网络

翻译译者

Licia

审核员

审核员YX

视频来源

https://www.youtube.com/watch?v=X_tYrnv_o6A

相关推荐