逻辑关系

转折 、因果 、提问(?) 、强调(!) 、否定(-) 、对比 、举例(ex) 、

[ 理论课 - 讲座 ]

Teacher: I'm sure most of you know that we've been able to extract certain compounds from plants for use in medicine, Um, compounds like proteins. Proteins from some plants can be used in medicines as antibodies in vaccines. And we can even cause some plants to produce certain proteins by incorporating DNA into the plants' cells, usually in the leaves. We then extract the proteins to use as antibodies.

However(转折), we've never been able to produce enough protein to make the process worthwhile. It hasn't been practical, until now. Now it appears that it is possible to get a large amount of useable protein from plants. Some researchers have recently succeeded in doing this by using plant seeds to produce these proteins, rather than the leaves or the other parts of the plant.

Now there are a number of advantages to getting protein from plant seeds to produce antibodies. But(转折) we have to be sure that these proteins are just as effective as human proteins, and so far the research has shown they are. That antibodies produced from plants seed proteins are effective in humans, which is great. Because typically antibodies for vaccines and medicines too are produced from microorganisms like yeasts or bacteria and it's a rather complicated process.

Okay, so what(提问) makes plant seeds good production units? Well, for one thing(并列), there's lots of them right? One plant can produce a lot of seeds. And then(并列) there's the issue of storage. Seeds can be stored for long periods of time, and the protein retains its effectiveness. Now that's not true with other parts of the plant. Leaves for instance, you can't store them very long which means that you have to get that protein out right away, as soon as it's produced. But using plant seeds as production units, allows you to isolate the protein whenever you need it. And you can transport seeds all over the world. Even to places where refrigeration might be a problem. Not so for yeast or bacteria. But with seeds, it seems quite possible that we'll be able to supply vaccines to places that need them. Whereas before, transporting and preserving these products over long distances simply wasn't feasible.

And another major(强调) benefit of extracting plant proteins for medical use, it's cost-effective. Unlike the production of proteins for medicinal purposes using yeast or bacteria, like insulin which is a vital protein used in medications, extracting protein from seeds doesn't(否定) require high-tech production labs with all kinds of equipment. And since refrigeration is not crucial for maintenance or transport, it's just much less expensive to store and maintain plant seeds than other sources of protein. We estimate the total production cost to be 10 to 100 times lower.

1 What is the lecture mainly about

The costs of extracting proteins from plants to make vaccines

The modification of seeds to increase plant reproduction

The benefits of using plant seeds to obtain proteins for vaccines

The use of proteins in animal cells to produce vaccines

2 According to the professor, what did the researchers learn about proteins produced from plant seeds

They produce antibodies that are effective in humans.

They are difficult to extract.

They are more suitable for medicinal use than antibodies produced from bacteria and yeasts.

They do not survive as long as proteins produced from leaves.

3 According to the professor, what is an advantage of using plant seeds rather than plant leaves to extract proteins

Proteins can be extracted more quickly from seeds than from leaves.

Proteins from seeds are more effective as medication.

Seeds can be stored without the proteins' losing their effectiveness.

A single seed provides more protein than a single leaf.

4 Why does the professor mention insulin

To give an example of a protein that is used as medicine

To point out the most common protein produced from plant seeds

To give an example of a medication that can be stored for a long period

To explain why it is difficult to extract proteins from plants

5 Why does the professor discuss refrigeration

To emphasize the expense of producing proteins from plant seeds

To point out the cost-effectiveness of transporting seeds

To illustrate the difficulty of preserving some vaccines made from seed proteins

To emphasize the need for more high-tech laboratories for extracting plant proteins

6 Why does the professor say this:

To remind students of a lab experiment they recently completed

To encourage students to provide a summary of a previous lecture

To point out something that she thinks the students might not know

To use common knowledge to establish a starting point for the lecture

        medicine  n. 医学;药;(尤指)药水

        extract  vt. 摘录;提取;提炼;索取

        antibody  n. 抗体(血液中抵抗疾病或当某些物质进入身体时产生反应的物质)

        leaves  n. 叶;叶片;叶子; - leaf

        incorporate  vt. 合并;包含;将…包括在内;吸收;使并入;注册成立

        worthwhile  adj. 值得的;重要的;

        practical  adj. 实际的;真实的;客观存在的;切实可行的;有用的;适用的;明智的

        appear  v. 显得，看来，似乎;出现，呈现，显现;

        typically  adv. 典型的;通常;一般;典型地;具有代表性地;不出所料;果然

        so far  目前为止，迄今为止;（只能到）如此程度，这个地步

        retain  vt. 保持;保留;持有

        effectiveness  n. 有效性;效率（果，力，用，能，应）

        as soon as  一…就…

        right away  马上

        Not so  不是这样

        quite  adv. 相当地;相当;很;非常;十分;完全;

        cost-effective  adj. 性价比高的;划算的;有最佳利润的;有成本效益的

        lab  n. 实验室;同 laboratory;实验大楼;实验课;化学厂，药厂

        10 to 100 times  10到100倍

笔记

proteins enough- seeds+

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adv seed = human

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① lot

② storage+

③ cost-effective lab-