(完整版)細(xì)胞膜—系統(tǒng)的邊界知識(shí)點(diǎn),推薦文檔

1、細(xì)胞膜系統(tǒng)的邊界1. 細(xì)胞膜的成分脂質(zhì)(約 50%)主要是磷脂，還有部分膽固醇，磷脂作為細(xì)胞膜的骨架。蛋白質(zhì)(約 40%)主要作為運(yùn)輸載體。細(xì)胞功能越復(fù)雜，蛋白質(zhì)種類及數(shù)量就越多。糖類(約 2%10%)主要與蛋白質(zhì)和脂質(zhì)結(jié)合形成糖蛋白和糖脂。主要起識(shí)別和信息傳遞的作用。注：細(xì)胞膜的組分也會(huì)發(fā)生變化，如癌細(xì)胞膜上糖蛋白含量下降，產(chǎn)生甲胎蛋白和癌胚抗原等物質(zhì)。2. 細(xì)胞膜的結(jié)構(gòu)(見本單元第 4 章)3. 細(xì)胞膜的功能分析(1) 將細(xì)胞與外界環(huán)境隔開，形成一個(gè)相對獨(dú)立的系統(tǒng)。(2) 控制物質(zhì)進(jìn)出細(xì)胞。細(xì)胞需要的物質(zhì)可進(jìn)入，代謝廢物排出細(xì)胞，細(xì)胞不需要的物質(zhì)不容易進(jìn)入細(xì)胞，控制作用是相對的，某些病毒，

2、病菌等也能進(jìn)入細(xì)胞使生物體患病。(3) 進(jìn)行細(xì)胞間的信息交流物質(zhì)傳遞（間接）：通過細(xì)胞分泌的化學(xué)物質(zhì)，隨血液到達(dá)全身各處，與靶細(xì)胞表面的受體結(jié)合，將信息傳遞給靶細(xì)胞。激素接觸傳遞（直接）：通過相鄰兩細(xì)胞的細(xì)胞膜接觸，使信息從一個(gè)細(xì)胞傳遞給另一個(gè)細(xì)胞如精卵結(jié)合通道傳遞：相鄰兩植物細(xì)胞之間形成通道，攜帶信息的物質(zhì)從一個(gè)細(xì)胞傳遞給另一個(gè)細(xì)胞 胞間連絲實(shí)驗(yàn)：體驗(yàn)細(xì)胞膜制備的方法1. 實(shí)驗(yàn)原理(1) 動(dòng)物細(xì)胞沒有細(xì)胞壁，選擇動(dòng)物細(xì)胞更易制備細(xì)胞膜。(2) 動(dòng)物細(xì)胞在清水(低滲溶液)中易吸水漲破，細(xì)胞內(nèi)的物質(zhì)流出，即可得到細(xì)胞膜。(3) 哺乳動(dòng)物紅細(xì)胞中沒有細(xì)胞核及各種具膜的細(xì)胞器，避免了細(xì)胞膜與核膜、細(xì)

3、胞器膜分離的麻煩，經(jīng)離心即可得到較純凈的細(xì)胞膜。2. 實(shí)驗(yàn)流程制作臨時(shí)裝片：在潔凈載玻片上滴一滴紅細(xì)胞稀釋液后，加蓋蓋玻片。（取得紅細(xì)胞后應(yīng)先用適量的生理鹽水稀釋，目的是：紅細(xì)胞分散開，不易凝集成塊。使紅細(xì)胞暫時(shí)維持原有的形態(tài)。）低倍鏡觀察：尋找觀察點(diǎn)，并移至視野中央，換用高倍鏡（觀察細(xì)胞原有形態(tài)）與后續(xù)實(shí)驗(yàn)對照。引流法：在蓋玻片一側(cè)滴加一滴蒸餾水，同時(shí)在另一側(cè)用吸水紙小心吸引，注意不要把細(xì)胞吸跑。在載物臺(tái)上進(jìn)行。持續(xù)觀察變化：正常形態(tài)凹陷消失細(xì)胞破裂內(nèi)容物流出。3. 如果該實(shí)驗(yàn)過程在試管中進(jìn)行，要想獲得較純凈的細(xì)胞膜，紅細(xì)胞破裂后，還必須經(jīng)過離心，過濾才能成功?！啊薄啊盿t the end,

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