2018年4月13日SAT阅读每日一题 5月sat备考ing

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为广大SATer带来2018年4月13日的SAT阅读每日一练，考察语篇阅读中的行文理解能力，先有针对性在文章出题去做快速阅读，再做推断，最后通读全文，积累词汇。反复咀嚼，岂不妙哉。

4月13日SAT阅读每日一练

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.

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.

In the first paragraph, the example of an opera house primarily serves to

_________

在第一段中，举歌剧院的例子主要用来做什么

A. clarify the reader's understanding of the role of a cell's membrane

channels.

B. highlight differences between the structural components of buildings and

the structural components of cells.

C. help the reader visualize the size of a glycerol facilitator relative to

that of a cell.

D. suggest the complexity of the process by which cell membranes develop.

答案：A

解析：

Choice A is the best answer. The author uses the familiar concept of a

building with different entrances -- in this case, an opera house with one door

for the audience and another door for the performers -- to help the reader

understand that cell membrane channels are entrances that allow different

molecules into a cell.

4月13日SAT阅读每日一练推荐词汇

block[blɔk]n. 街区，木块，石块 . 阻塞(物), 障

bond[bɔnd]n. 债券，结合，粘结剂，粘合剂 vt. 使结

configuration[kən.figju'reiʃən]n. 结构，布局，形态，格式塔心理完形 [计算机] 配置

filter['filtə]n. 筛选，滤波器，过滤器，滤色镜 v. 过滤

highlight['hailait]n. 加亮区，精彩部分，最重要的细节或事件，闪光点

bacterium[bæk'tiəriəm]n. 细菌

exclusive[iks'klu:siv]adj. 独占的，唯一的，排外的 n. 独家

protein['prəuti:n]n. 蛋白质

cell[sel]n. 细胞，电池，小组，小房间，单人牢房，(蜂房的)巢室

understand[.ʌndə'stænd]vt. 理解，懂，听说，获悉，将 ... 理解为，认为

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