10中山大學(xué)本科生細(xì)胞生物學(xué)復(fù)習(xí)資料全-在線瀏覽
2025-06-28 22:04本頁面
【正文】 to Gm protein causing a conformational change in the Gsa protein and release ofthe bound GDP. GTP then binds to Gsa which causes release of the GTPGsa plex from the b and 161。主動(dòng)運(yùn)輸涉及物質(zhì)輸入和輸出細(xì)胞和細(xì)胞器,并且能夠逆濃度梯度或電化學(xué)梯度。② 能夠?qū)⒓?xì)胞內(nèi)的各種物質(zhì),如分泌物、代謝廢物以及一些離子排到細(xì)胞外,即使這些物質(zhì)在細(xì)胞外的濃度比細(xì)胞內(nèi)的濃度高得多。概括地說，主動(dòng)運(yùn)輸主要是維持細(xì)胞內(nèi)環(huán)境的穩(wěn)定,以及在各種不同生理?xiàng)l件下細(xì)胞內(nèi)環(huán)境的快速調(diào)整, 這對(duì)細(xì)胞的生命活動(dòng)來說是非常重要的。4. 胰高血糖素和腎上腺素是如何使靶細(xì)胞中的cAMP 的濃度升高的?答: 胰高血糖素和腎上腺素作為第一信使作用于靶細(xì)胞的膜受體, 通過G 蛋白偶聯(lián)細(xì)激活腺苷酸環(huán)化酶,將ATP生成cAMP。6. 為什么說水是細(xì)胞中優(yōu)良的熱緩沖體系？答：使一克水的溫度上升一攝氏度所需要的能量是1 卡。水吸收的大部分能量被用來破壞分子間氫鍵，這些氫鍵是由于水分子的極性和不對(duì)稱性造成的。在此種意義上，環(huán)境溫度的變化可以在細(xì)胞中被緩沖。(簡要說明，不需詳細(xì)步驟。1. Some integral membrane enzymes depend upon the lipids in their microenvironment not only for scaffolding, butfor enzymatic activity. The Na+K+ ATPase is one example. Please design an experiment to test the influence ofmembrane fluidity on the velocity of the Na+K+ ATPase.Answers:1. Identify a tissue that would serve as a good source of the enzyme of interest, ., the plasma membranes of nervetissue. Solubilize the Na+K+ ATPase from its native membrane using detergents. Reconstitute the enzyme intoliposomes of simple and welldefined position, then assay the enzyme for activity. By synthesizing a variety ofliposomes with different amounts of saturated and unsaturated fatty acids, the fiuidity of the liposome can be altered,and the enzyme can be tested under conditions of different fiuidity. (To measure the fiuidity of the liposomes directly,without having to infer it from the fatty acid position, either FRAP or SPT techniques can be applied.)2. 如何證明RNA 聚合酶Ⅲ進(jìn)行5S rRNA 基因轉(zhuǎn)錄時(shí), 使用的是內(nèi)部啟動(dòng)子?可通過基因操作。實(shí)驗(yàn)結(jié)果表明: 將5S rRNA 基因的5＇側(cè)的上游序列完全除去并不影響5S rRNA 基因的轉(zhuǎn)錄。如果將5S rRNA 基因的內(nèi)部啟動(dòng)子序列插入到基因組的其它部位，會(huì)使插入的部位形成一個(gè)新的轉(zhuǎn)錄起點(diǎn)。表明5S rRNA 基因的啟動(dòng)子位于5S 基因內(nèi)部的控制區(qū)。例如,放射性標(biāo)記的胰島素與受體的結(jié)合不會(huì)受葡萄糖或ACTH(促腎上腺皮質(zhì)激素)的抑制,但是能夠被非放射性標(biāo)記的胰島素或胰島素衍生物所抑制(圖E52)。與胰島素?zé)o關(guān)的激素不會(huì)與放射性標(biāo)記的胰島素競爭質(zhì)膜受體。六、分析、計(jì)算與思考(20 分)1. “解鈴還需系鈴人”這句諺語在細(xì)胞活動(dòng)中能找到對(duì)應(yīng)的故事嗎？請(qǐng)說明。2. 計(jì)算題（5 分）① The average molecular weight of proteins in the cell is about 30,000daltons. A few proteins, however, are very much larger. The largest knownpolypeptide chain made by any cell is a protein called titin (madeby muscle cells), and it has a molecular weight of 3,000,000 daltons.Estimate how long it will take a muscle cell to translate an mRNA codingfor titin (assume the average molecular weight of an amino acid to be 120,and a translation rate of two amino acids per second for eucaryotic cells).② Transcription occurs at a rate of about 30 nucleotides per second. Is itpossible to calculate the time required to synthesize a titin mRNA fromthe information given here?2. Answer:① A titin molecule is made of 25,000 amino acids. It therefore takes about hours to synthesize a single molecule of titin in muscle cells.② To calculate the time it takes to transcribe a titin mRNA, you would needto know the size of its gene, which is likely to contain many introns.Transcription of the exons alone requires about 42 minutes. Becauseintrons can be quite large, the time required to transcribe the entiregene is likely to be considerably longer.2. 綜合思考(10 分, 按答題最多者計(jì)算每題得分)① 物質(zhì)運(yùn)輸是一個(gè)耗能過程，請(qǐng)舉例說明有哪些能量來源？答：①自由能；②ATP；③光能；④磷酸烯醇式丙酮酸；⑤動(dòng)力勢(shì)（協(xié)同）②． What is the advantage of having an extracellular signal transmittedby a cascade of sequential events?Answer②:Transduction of an extracellular signal via a cascade of sequential events is advantageousbecause of the amplification of the signal. The binding of a few molecules to a receptor can resultin the synthesis of
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