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SAT考试:SAT阅读真题详解

760人浏览 2018-11-13 分享到|

  现在有许多的小伙伴都在备考SAT考试,而有很多的人都觉得SAT阅读很难拿高分,那有没有什么可以提高SAT阅读分数的方法呢?其实还真有,那就是刷题,多做练习,那么今天小编就大家带来了一道SAT阅读题,一起来做做吧。

  Like an opera house, which has its public entrance separate from that for the performers, a cell has different doors for different molecules. Each gets scrutinized at its door before it can enter the cell. Now researchers from the University of California at San Francisco have revealed in the journal Science the three-dimensional structure of one such door, or membrane channel, that specializes in granting entry to a membrane component known as glycerol. Specifically the channel is called the glycerol facilitator (GlpF), from the bacterium Escherichia coli.


SAT考试:SAT阅读真题详解


  Bearing three alcohol groups, glycerol is a basic building block for the cell membrane. (Other components include fatty acids and small charged molecules.) And not just in E. coli. Indeed, although the channel the researchers studied is from a bacterium, it belongs to a large protein family dubbed the aquaporins, which are found in species ranging from bacteria to humans.

  GlpF is highly specific for glycerol and similar polyalcohols. Somehow, even though water molecules are much smaller, they cannot enter. The new study reveals why. In order for glycerol to clear the four-channel configuration in the cell membrane, it must pass through a narrow selectivity filter in the center of a channel. Here it is surrounded by amino acids that closely match its own structure, which is hydrophilic ("water-loving") on one side and hydrophobic ("water-fearing") on the other. Water molecules, in contrast, can only pass through this area in single file, which is not energetically favorable, because they like to bond to one another. And ions, which are charged, are unable to pass the "water-fearing" side of the channel. This cell entrance, it seems, is truly exclusive.

  The underlined word "granting" most nearly means __________

  与granting意思最接近的单词是

  A. consenting.

  B. fulfilling.

  C. permitting.

  D. transferring.

  答案:C

  解析:

  Choice C is the best answer. The context makes it clear that when the author says the membrane channel specializes in "granting entry to a membrane component," she means that the membrane channel's job is to permit entry to the membrane component, or to allow the membrane component to move into the cell.

  以上就是小编今天带来的全部内容,希望大家是否做对了呢?想了解更多关于SAT阅读真题SAT美国历史真题的内容,可以关注微信公众号kewo11。


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SAT考试:SAT阅读真题详解

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