『新东方在线托福听力』为托福考生准备了ETS托福TPO/Official 39 Lec 4听力练习：The professor describes the current method for producing cellulosic ethanol. What are the two important steps she mentions?原文题目答案解析，TPO/Official 39 Lec 4听力原文范文音频翻译。

托福TPO/Official 39 Lec 4听力原文The professor describes the current method for producing cellulosic ethanol. What are the two important steps she mentions?【新东方在线】

旁白：请听一段生物学讲座的节选片段。

Narrator: Listen to part of a lecture in a biology class.

教授：大家今天的阅读材料是关于潜在的能源来源。

Professor: Your reading for today's class was about potential alternative sources of energy.

我今天要做的事情之一就是来讨论其中一种潜在的能源来源之一就是：纤维素。

So one thing I want to do today is consider one of those potential energy sources: cellulose.

谁可以告诉我纤维素是什么？Alan？

学生：纤维素。是的。这是一种由简单糖类构成的坚硬的有机分子。

Student: Cellulose. Yeah. It's a tough organic molecule made of simple sugars.

它被发现在所有的植物细胞里，青草，树木，所有的植物。

It's found in the walls of all plant cells, in grass, trees, all plants.

在地球上，纤维素是最多的有机粒子。

And well, there's more cellulose than any other organic molecule on Earth.

教授：好的。在某种程度上纤维素也是一种大量的潜在能源因为自然界里储量丰富。

Professor: Good. It's also a potential tremendous source of energy in part because there's so much of it.

很多有机体靠消化纤维素产生的能量而生存，就像是很多种类的细菌或者母牛和山羊一样。

Now, many organisms live on the energy they derive from consuming cellulose, like many species of bacteria or cows and goats.

母牛和山羊进化出了高度特殊化的消化系统，这个消化系统可以让它们消化掉纤维素。

Cows and goats have evolved highly specialized digestive systems that allow them to metabolize cellulose.

学生：但是对于大多数物种而言，加工处理纤维素是困难的？

Student: But it's hard for most species to process cellulose?

教授：是的。而且研发出一种在我们控制之下的方式，在实验室里加工处理纤维素让我们使用储存在其中的能量是很难的。

Professor: Yes. And it's been very hard to develop a controlled way to process cellulose in a lab so that we can use the energy that's stored in it.

乙醇是液体，一种酒精，这种物质来自于从植物中产生糖的过程，原料一般是玉米。

Ethanol is a liquid, a kind of alcohol that's derived from processing sugars from plants, often corn.

很多研究者相信，纤维素可以终结人类对于汽油的依赖。

Many researchers believe it is the key to ending the reliance on gasoline.

问题是我们现在从玉米产生的乙醇中获得的能量并没有花在产生它上面的能量多。

The problem is that the amount of energy we get from corn-based ethanol isn't much more than the amount of energy that gets put into making it.

学生：但是从纤维素中制造的乙醇不一样？

Student: But ethanol made from cellulose is different?

教授：是的。产自纤维素的或者纤维素类乙醇的能量，可能质量更好。

Professor: Yes. It's possible to get a vastly better energy yield on cellulose-based or cellulosic ethanol.

学生：好吧。所以为什么我们不直接使用纤维素乙醇呢？

Student: Okay. So why don't we just use cellulosic ethanol?

教授：问题就是，现在的把纤维素加工成乙醇的技术还很贵，而且不能大批量转化。

Professor: Well, the problem is that the current method for processing cellulose into ethanol is very expensive and can't be done on a large scale.

明白了吗？现在这个转化过程主要有两个关键步骤。

See? Currently there are two key steps in the process.

第一步是把纤维素分解成糖类。

The first is breaking the cellulose down into sugars.

这需要通过酶来完成，酶是一种特殊的蛋白质。

This is done with an enzyme, a specific type of protein.

第二点，在酶把纤维素分解了之后，酵母和其他的微生物、细菌等会被加入，来发酵这些糖类，最后生成纤维素乙醇。

And second, after the enzyme has broken down the cellulose, yeast and other microorganisms, microbes are added to ferment those sugars into cellulosic ethanol.

问题是，我们在生产这些分解纤维素的酶的时候并没有很成功。

Thing is, though, we are not too good at producing the enzymes that break down cellulose.

这些蛋白质很难生产，即使是在实验室里。

Those proteins are very difficult to make, to just assemble in a lab.

所以通常来说我们会在产生它们的微生物里直接提取这种酶。

So usually we extract enzymes from microorganisms that produce them naturally.

不幸的是，这个过程很慢，很贵，而且效率不高。

Unfortunately, this is slow, expensive, and just not very efficient.

学生：所以科学家正在努力研发一种生产酶的更好的办法？

Student: So are they trying to develop a better way to make enzymes?

教授：实际上有一家公司觉得他们可以做的更好。

Professor: Actually there's a company that thinks they can do better than that.

把这两个步骤合二为一可以更高效，更经济。

It'd be more efficient and therefore cheaper to combine the two steps I mentioned into one.

意思是，我们可以找到一种有机物，既可以分解纤维素也可以把它转化成乙醇。

That is, have a single organism that breaks down cellulose and then produces ethanol.

所以这家公司做的是在全世界寻找并收集这种自然界中就有的有机物。

So what this company is doing is searching around the world and gathering naturally occurring microorganisms that do both things.

我的意思是，开发纤维素所含能量的关键可能藏在某个丛林里的特殊种类的细菌或者酵母身上。

I mean, the best key to unlocking the power of cellulose may well lie in a rare species of bacteria or yeast in a jungle somewhere.

所以这个公司的研人员已经发现了一些微生物，这些微生物可以把纤维素转化为乙醇。

So researchers at this company have discovered some microorganisms that process cellulose and produce ethanol.

现在他们正忙于加强、改进这些微生物的某种自然特征，通过某种复杂的科技操纵它们，来让它们转化得更有效率。

Now they are working on enhancing, improving certain natural characteristics of these microorganisms, manipulating them with sophisticated technology to make them work even more efficiently.

现在看来已经近在咫尺的目标是设计一个“工程师”，一个超级虫子，一个特定种类的微生物，这个微生物可以使得对于纤维素乙醇的便宜经济的转化变成可能。

The goal, which seems to definitely be within reach, is to design an engineer, a superbug, a specific kind of microbe, that makes cheap, commercial production of cellulosic ethanol a really possibility.

According to the speakers, why is cellulose such a significant potential source of energy?

What is the professor's opinion about corn-based ethanol?

The professor describes the current method for producing cellulosic ethanol. What are the two important steps she mentions?

What does the professor imply about a superbug?

北美留学考试	英联邦留学考试	专业问答
TOEFL	IELTS	雅思专业问答
GRE	A Level	托福专业问答
GMAT	PTE	GRE专业问答
SAT	Interchange	GMAT专业问答
ACT	英本精英计划
AP/SSAT/IB
美高先修课
美本精英计划
美研精英计划