lori asked in 科學及數學生物學 · 1 decade ago

請英文高手幫下手翻譯~~急!急!急!

請翻譯做英文!!

大部分成熟的植物細胞,都有一個很大的液泡(vacuole),當液泡內充滿水分時,就壓迫周圍的細胞質,使它緊緊貼向細胞壁,而給予細胞壁一種壓力,這就是膨壓。膨壓使得細胞壁處於繃緊狀態,像吹滿了氣的氣球一樣。液泡內所含的有機和無機物質,它們濃度的高低,決定滲透壓的高低,而滲透壓的高低可以決定水分擴散的方向。當液泡濃度增高時,滲透壓增加,水分由胞外向胞內擴散而進入液泡,增加細胞的膨壓,使細胞鼓脹;反之,細胞則萎縮。這種過程只能造成緩慢的運動,例如氣孔的開合等,但是當胞膜的半透性發生霎時的變化時,卻也可以引起相當迅速的動作。

在平常,由於細胞膜和液泡膜的差異通透性及主動運輸之作用,將氯離子(Cl-)向細胞內,陽離子向細胞外運送,使得胞膜和鄰近地區保持一定的電位差,叫做靜止電位(resting potential)。我們也可以說胞膜是處在一種極化狀態(polarized)下。因為是陰離子聚集在細胞內,所以胞膜的電位是負的。當外界刺激超過某一定限度時,這種差異通透性會突然改變,鈣離子 (Ca++)大量涌進細胞,鉀離子(K+)卻向相反方向進行,使膜內電位增高,甚至成為正電位,於是產生了動作電位(action potential),這種現象叫做「去極化」(depolarization)現象。動作電位可由接受刺激的部位向四方傳遞,使整個細胞都產生去極化現象,然後再傳到下一個細胞,這樣動作電位可以一直不斷地傳遞下去。當細胞到達動作電位時,也就是產生去極化現象時,胞膜的差異通透性消失,原來蓄存於液泡內之水分遂在瞬間排出,使細胞失去膨壓,變得癱軟。

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  • Anonymous
    1 decade ago
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    Most ripe plant cells, all have a very big vacuole (vacuole) ,When full of moisture in the vacuoling, oppress the cytoplasm around, make it stick to the cell wall tightly, and offer the pressure of one kind of cell walls, this is to expand and is pressed. It makes the cell wall in the state of tightening to expand and press, like blowing the balloon of all over air. The organic and inorganic substance included in the vacuole, the level of their thickness, determine to permeate the level pressed, and permeating the level pressed can determine the direction in which the moisture spreads. When the vacuole thickness increases, permeate and press and increase, the moisture spreads and enters the vacuole from the export-oriented afterbirth of afterbirth, increase the expanding and pressing of cells, make cells ballooning; On the contrary, cells wither. This kind of course can only cause slowly sports, for example the air vent is opened and shut etc., but sex take place change in a twinkling,

    請英文高手幫下手翻譯

    Source(s): 天之心
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