今天上午作了presentaion的预讲 - 未名空间MITBBS历史存档

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今天上午作了presentaion的预讲

今天上午作了presentaion的预讲# Biology - 生物学

s*e2000-02-23 08:02

1 楼

老板把关,结果超时, 而且不够清楚. 本周末再次预讲, 之后就是真正去APS 2000年会
讲了. 我重新整理了一下, 这里用中文说说, 看看大家有什么建议.THX...
Type II Topoisomerases 能够改变环状DNA的拓扑结构. 它可以附着在DNA上, 在附着
点把DNA的双链切开一个口, 使的这个DNA分子的其它部分能够穿越这个口子. 然后
TOPO II就把这个口子修复. 这就是所谓TOPO II的gate模型. 虽然反应过程中切口和修复
都不需要ATP释放的能量, 但是ATP被发现参与了整个反应过程.一般认为ATP的能量用来使
TOPO II复位.
最简单的也是一向被广泛接受了反应模型模型是"自由穿越模型:
K1----->U1 with transition rate R(K->U)
K1K)
其中K1代表一个knot DNA分子,有一个TOPO II附着在上面; U1代表一个Unknot DNA
分子,有一个TOPO II附着在上面. 用C(K),C(U)分别表示Knotted/Unkn

s*k2000-02-23 08:02

2 楼

请允许我这个半瓶醋插两句嘴:-)
大家知道在细菌里染色体是环形的,质粒也是环形的.
那么当它们复制的时候,到了最后关头,就会形成一种
两环互相套在一起的局面. (这个在数学上好象叫knot
我不大敢肯定,希望专家指正) 这时候,正是Topo II
挺身而出,解决了这一尴尬局面,将两个环彻底分离.
ATP若是参与到这个反应,没看文献,按照我的猜测可能
用于断开双链DNA,即形成一个dsDNA-->2ATP的中间体,
以打断DNA.当另一双链DNA穿过dsDNA的断端,酶再将
ATP水解会来,所以整个反应没有ATP的净消耗.
现在教主面临的问题是:
反应既然没有能量的消耗,为什么反应产物却不是处于
统计上的平均分布?
Roca 的工作从酶的作用机理和DNA的超螺旋性上这一
微观角度来解释这一问题.
而教主的工作是从热力学和分子动力学这一宏观角度
解释这一问题.
不知道以上我的这些说法是不是漏洞百出,还请专家斧正.

s*e2000-02-23 08:02

3 楼

自由模型里面,酶对反应过程不作功,所以适合用热力学的原理.最终分布也就是
平衡态分布. 可是根据实验的结果,酶催化的这个反应远离平衡态, 这样就不是
平衡态物理学适用的了. 所以最终分布由反应的稳态(就是个组份的浓度不随
时间变化)决定的. 酶就象个电池,一直在主动的干扰反应过程. 能量来自它
带的ATP. 98年有个实验,表明一个反应的cycle中,这个酶要使用两个ATP. 这
是为什么我们文章里面有两个ATP催化的单向过程.
所以这个反应是个被外界驱动的反应, 不能用能量最低原理来讨论.

m*m2000-02-23 08:02

4 楼

不懂，但是顶牛人！

H*g2000-02-23 08:02

5 楼

Just my two cents... Sorry I am not in your field, and do not know how long
your talk is supposed to be. I assume it is 20 min (18min for talk and 2min
for questions).
While for every talk that I attend, I am always expecting the speaker starts
from the big picture. For your case and from your description, I guess you
may start from an even bigger picture. Basically, why should I care about
your research? Do not start with something about topoisomerase, try to start
from something everyone knows and gradually points out what is currently
missing in the big picture.
For the body of your presentation, you may drop some of the details but show
your logic. It seems you focused two much on details (unless you have one-
hour slot for your talk). Especially how your discovery fills in the gap and
how this would change how we understand biology. If anyone is more
interested, they will ask questions in the question session, or go to your
poster, or check with you later.
Try to make a story and draw a model at the end and GO BACK to the big
picture with your contributions.
I guess if you could drop some details and accomplish the above points, you
could at least get rid of the 'Not Clear' and 'Over Time' issues which you
mentioned in your first sentence. Good luck.
One more thing which always annoys me, please do not read what you put in
the slides during your talk. Everyone at the talk can read.

w*a2000-02-23 08:02

6 楼

这帖子回的...

long
2min
starts
you
start
show

【在 H*g 的大作中提到】

: Just my two cents... Sorry I am not in your field, and do not know how long
: your talk is supposed to be. I assume it is 20 min (18min for talk and 2min
: for questions).
: While for every talk that I attend, I am always expecting the speaker starts
: from the big picture. For your case and from your description, I guess you
: may start from an even bigger picture. Basically, why should I care about
: your research? Do not start with something about topoisomerase, try to start
: from something everyone knows and gradually points out what is currently
: missing in the big picture.
: For the body of your presentation, you may drop some of the details but show

H*g2000-02-23 08:02

7 楼

What's up? He does not ask about science. He asks how to improve his
presentation.

【在 w***a 的大作中提到】

: 这帖子回的...
:
: long
: 2min
: starts
: you
: start
: show

x*h2000-02-23 08:02

8 楼

这坟挖的……排骨同学都天牛了，当初挖坑的时候这里很多人都还在高中做着 21 世纪
是某某世纪的美梦吧，哈哈。

H*g2000-02-23 08:02

9 楼

这坑挖的……

i*s2000-02-23 08:02

10 楼

Agree with Hug. It is very important to give a big picture at the very
beginning. Otherwise why should the audience care about your work?

C*e2000-02-23 08:02

11 楼

2000年的帖子为什么给翻出来了？
谁挖的？

修复
来使

【在 s***e 的大作中提到】

: 老板把关,结果超时, 而且不够清楚. 本周末再次预讲, 之后就是真正去APS 2000年会
: 讲了. 我重新整理了一下, 这里用中文说说, 看看大家有什么建议.THX...
: Type II Topoisomerases 能够改变环状DNA的拓扑结构. 它可以附着在DNA上, 在附着
: 点把DNA的双链切开一个口, 使的这个DNA分子的其它部分能够穿越这个口子. 然后
: TOPO II就把这个口子修复. 这就是所谓TOPO II的gate模型. 虽然反应过程中切口和修复
: 都不需要ATP释放的能量, 但是ATP被发现参与了整个反应过程.一般认为ATP的能量用来使
: TOPO II复位.
: 最简单的也是一向被广泛接受了反应模型模型是"自由穿越模型:
: K1----->U1 with transition rate R(K->U)
: K1K)