二氧化硅在细胞中可降解

Degradation of hollow mesoporous silica nanoparticles in human umbilical vein endothelial cells

Wanyin Zhai,1Changliang He,2Lei Wu,3Yue Zhou,4Hangrong Chen,1Jiang Chang,1

Hongfeng Zhang2

1State Key Laboratory of High Performance Ceramics and Super?ne Microstructure,Shanghai Institute of Ceramics,

Chinese Academy of Sciences,Shanghai200050,People’s Republic of China

2School of Life Science,East China Normal University,Shanghai200062,People’s Republic of China

3State Key Lab of Transducer Technology,Shanghai Institute of Microsystem and Information Technology,Shanghai200050, People’s Republic of China

4Med-X Research Institute,Shanghai Jiao Tong University,Shanghai200030,People’s Republic of China

Received25November2011;revised20February2012;accepted11March2012

Published online7May2012in Wiley Online Library(https://www.wendangku.net/doc/db10338426.html,).DOI:10.1002/jbm.b.32711

Abstract:Hollow mesoporous silica nanoparticles(HMSNs) are considered a potential drug delivery system owing to their recognized advantages in drug loading and releasing.However, whether HMSN could be degraded inside the cells remains unknown.In this study,based on the observations by transmis-sion electron microscopy,?uorescence staining,enzymatic pro-teolysis,and inductively coupled plasma atomic emission spectroscopy,HMSNs were proved to be degradable in human umbilical vein endothelial cells.The degradation?rst took place in cytoplasm and lysosomes,and secondly in lysosomes only.The Si content in culture medium increased as the time increases,suggesting that the degradation product inside the cells could be excreted into the culture medium.The degrading rate is fast in the?rst2days and slow after2days.The present results provided a clue to further research on the metabolic way and cytotoxicity of silica nanoparticles.V C2012Wiley Periodicals, Inc.J Biomed Mater Res Part B:Appl Biomater100B:1397–1403,2012.

Key Words:mesoporous silica nanoparticles,endothelial cell, degradation,cytoplasm,lysosome

How to cite this article:Zhai W,He C,Wu L,Zhou Y,Chen H,Chang J,Zhang H.2012.Degradation of hollow mesoporous silica nanoparticles in human umbilical vein endothelial cells.J Biomed Mater Res Part B2012:100B:1397–1403.

INTRODUCTION

Biodegradable organic and inorganic nanomaterials have been considered as drug delivery systems in many applica-tions.One could speculate that,ideally,the drug carrier sys-tem is able to degrade inside the cells,releasing the cargo completely and suf?ciently exerting the effect of the loaded https://www.wendangku.net/doc/db10338426.html,anic biodegradable materials can,to some extent, controllably release pharmaceutical drugs upon the struc-tural degradation.However,it is dif?cult to achieve‘‘zero’’premature release of the drugs as they are‘‘soft’’materials with unstable structures.1In recent years,‘‘solid’’drug deliv-ery systems,such as mesoporous silica nanomaterials(silica nanoparticles,SNps),have attracted extensive attentions.1,2 They can be loaded and release medicines,such as ibupro-fen,3–7gentamycin,8captopril,9camptothecin,10,11pro-teins,12,13salvianolic,14DNA,15and other therapeutic agents, enhancing delivery ef?cacy,minimizing deleterious side effects,heightening bioavailability,improving patient’s com-pliance,and protecting sensitive drugs from enzymatic or acidic degradation in the gastrointestinal tract.1,2‘‘Solid’’drug delivery systems are thought to be hardly degradable and may overcome the premature release.However,uneasy degradation may prevent them from metabolism,excreting away from body and complete drug release.Although highly charged mesoporous SNps can be excreted from the liver into the gastrointestinal tract,16whether these‘‘solid’’drug delivery systems could be degraded eventually in and excreted from cells is a critical question which relates to potential toxicity and thus needs to be answered before the clinical applications of these materials.1,17

Hollow mesoporous silica nanoparticle(HMSN)is one of the excellent candidates among the‘‘solid’’drug delivery system.They have tunable particle size,uniform and tuna-ble pore size with a narrow distribution,large surface area, and large pore volume.4,5,8,18–20Especially,HMSNs have a huge hollow core,as compared to conventional mesoporous SNps,for extraordinarily high-drug loading capacity.4,5,8Usu-ally,these hollow sphere nanoparticles are made within the

Correspondence to:J.Chang;e-mail:jchang@https://www.wendangku.net/doc/db10338426.html,

Contract grant sponsor:The National Hi-Tech Project of China(863Program);contract grant number:2007AA03Z317

Contract grant sponsor:The National Basic Science Research Program of China(973Program);contract grant number:2005CB522704

Contract grant sponsor:The Basic Science Research Program of State Key Laboratory of High Performance Ceramics and Super?ne Microstructure,Shanghai Institute of Ceramics,Chinese Academy of Sciences;contract grant number:SKL200910SIC

V C2012WILEY PERIODICALS,INC.1397

diameter of300–400nm,suitable for intravenous injec-tion.21Although mesoporous SNps have been proved to be uptaken into the cells within30min,1,10,22–26their degrada-tion behavior after being uptaken is still unknown.In this study,we explored the distribution and degradation of HMSN in human umbilical vein endothelial cells(HUVECs) to elucidate the possible metabolic way of HMSN. MATERIALS AND METHODS

Preparation of HMSN and FITC-conjugated HMSN HMSNs were prepared according to our previous report.27 Brie?y,1.0g polyvinylpyrrolidone(K30)and0.46g NaOH were dissolved into120-mL H2O with stirring.Then,1.40g cetyltrimethylammonium bromide(CTAB)was added.After CTAB being dissolved completely,5.6-mL TEOS was poured into the above solution under vigorous stirring.After24h stirring,the solution was heated at80 C for48h.The solid product was recovered by?ltration,dried under vacuum at room temperature,and calcined in air at550 C for10h to remove the templates.Finally,the prepared HMSNs were washed by75%ethanol solution and sterilized by ultravio-let radiation.FITC-conjugated HMSN was prepared accord-ing to the following procedure.First,20l L of3-aminopro-pyltriethoxysilane(APTES)was added into FITC(5mg,3 mL)ethanol solution under dark conditions and stirred for 24h to produce FITC-APTES.Second,HMSNs(20mg)were reacted with FITC-APTES stock solution(1mL)under dark conditions for24h.The FITC-conjugated HMSNs were col-lected by centrifugation at4000rpm and washed with 100%ethanol several times to remove the unreacted FITC-APTES.At the end,the FITC-conjugated HMSNs were dried under vacuum at room temperature.N2adsorption–desorp-tion isotherms were obtained on Micromeritics Tristar3000 at77K under a continuous adsorption condition to charac-terize the mesoporous structure.BET and BJH analyses were used to determine the pore volume.

Cell culture

If the HMSNs are intravenous injection as were reported earlier,21they will?rst touch and interact with the blood cells and vascular endothelial cells.In the present study,we choose a type of endothelial cell,HUVEC,as a model to investigate the HMSN degradation inside the cell.HUVECs were obtained from Invitrogen(Carlsbad,CA)and cultured in DMEM(Invitrogen,Carlsbad,CA)supplemented with2 mM glutamine,100U/mL penicillin,100mg/mL streptomy-cin,and10%fetal bovine serum(Sijiqing,Hangzhou,China). The cell cultures were carried out in an incubator in a humidi?ed atmosphere(5%CO2and95%air)at37 C. Distribution and morphological change of HMSNs

inside cells

To study the distribution and morphological change of HMSNs,cells(105cells/well)were inoculated in six-well plates and the medium was changed to HMSN solution(25 l g/mL in complete culture medium)after culturing for24 h.At1and2days,the cells were washed with phosphate buffered saline(PBS),?xed with glutaraldehyde and sec-tioned into slices.The morphology of HMSNs inside cells was observed by transmission electron microscopy(TEM; JSM-2100,JEOL,Tokyo,Japan).27To further explore the dis-tribution of HMSN,HUVECs were cultured on cover slips in culture dishes(U55mm)and treated with FITC-conjugated HMSNs(25l g/mL)for2,4,and7days.At2and4days, the cells were washed three times with PBS to stop the interaction of the HMSNs and stained by Lyso-Track Red for lysosome staining(Molecular Probes)and Hoechst33342 (Beyotime)for cell nucleus staining.The green?uorescence of the FITC-conjugated HMSN can be observed at488nm laser excitation and the red?uorescence on the lysosome can be observed at590nm by a laser scanning confocal microscope(LSM GB-200;Olympus,Tokyo,Japan).At7 days,the cells were washed with PBS,?xed with0.2%glu-taraldehyde in PBS,and observed by the laser scanning con-focal microscope to explore the degradation results. Degradation of HMSNs in cells

The cells in six-well plates(105cells/well)were incubated with125l g/well HMSN in DMEM supplemented with10% FBS for30min.After the incubation period,the medium with the excessive HMSN was removed.The cells were then washed with PBS for?ve times and culture medium was refreshed.At selected time points(5min,1day,2,3,4,5,6, and7days),culture medium was collected for measuring Si content.During the HMSNs degradation period(if they were),it is reasonable to speculate that there were both degraded(Si ions)and degrading HMSNs(small pieces of HMSN)simultaneously existing in the cells at each time point.The degraded and degrading HMSNs could be frac-tioned from the cell lysates by centrifugation at certain speed to yield HMSN-small pieces containing fractions.To con?rm the degradation of the HMSNs,at each time point,cells were sampled for Si content analysis according to the following procedure.After removing the culture medium,the cells were washed with PBS and frozen promptly underà18 C in a refrigerator.At the end of the experiment,all the samples were thawed and treated by1mL collagenase(1.5mg/mL in PBS,Sigma-Aldrich,C6885)for12h followed by proteinase XXIII(5mg/mL,Sigma-Aldrich,P4032)for6h to avoid the possible interfering of the proteins to the measurement of Si content.For separation of the product of degraded HMSNs, the cell lysates were divided in half to centrifuge(Jouan A14, France)at different speeds and for different times.One half of the sample was centrifuged at5600g for1min and the other half was centrifuged at11,000g for15min,yielding two supernatants referred as lysates-5600g and lysates-11,000g,respectively.In these supernatants,the HMSN-small pieces were theoretically bigger and in higher amount in lysates-5600g than in lysates-11,000g.Finally,the silicon content of the samples(1mL)obtained from both the cul-ture medium and the supernatant of the centrifuged cell lysates was directly determined by the inductively coupled plasma atomic emission spectroscopy(ICP-OES;Perkin Elmer,Optima3000DV,USA)without dilution.The samples collected after culturing for5min with HMSNs were used as the control group(day0samples).

1398ZHAI ET AL.DEGRADATION OF HOLLOW MESOPOROUS SILICA NANOPARTICLES IN HUMAN CELLS

Statistics

All data are presented as mean 6standard deviation.At minimum,three samples were represented for each data point.Statistical signi?cance between groups was calculated using two-tailed analysis of variance,performed with a com-puter statistical program (Student’s t -test)and p <0.05were considered statistically signi?cant.

RESULTS

Distribution of HMSN in cells

The prepared HMSNs were uniform in particle size with the diameter of 300–430nm (Figure 1),and have pore volume of 1.04cm 3/g and highly ordered mesoporous structure with a diameter from 2to 3nm similar to our previous report.5After culturing HUVECs with HMSN for 1day,HMSNs were observed in cytoplasm of the cells [Figure 2(b),indicated by arrows].Moreover,there were free par-ticles in the cytoplasm [Figure 2(b,c)]and accumulated par-ticles in the endocytic vesicles [Figure 2(d)],suggesting that the nanoparticles were able to enter the cells either by dif-fusion or by endocytosis.HUVEC cultured in the absence of HMSNs was presented as the negative control [Figure 2(a)].

Fluorescent staining showed that after 2days of culture,most of the HMSNs were located in the lysosomes of the cells [Figure 3(a–d)].After 4days of culture,all HMSNs were still accumulated in the lysosomes without any pieces of HMSNs being exocytosed [Figure 3(e–h)],indicating the transfer of HMSNs from cytoplasm into lysosomes from days 1to 4of culture.

Degradation of HMSN in cells

After 2days,some of HMSNs were found in different sizes either in or outside of lysosomes within cytoplasm [Figure 4(a)].Some of the HMSNs <200nm in diameter were found both outside [Figure 4(a)]and in lysosome [Figure

4(b)],

FIGURE 1.TEM morphology of

HMSN.

FIGURE 2.TEM micrographs of HMSN being uptake by HUVECs after 24h of culture.(a)Control;(b)HMSNs distributed into cytoplasm of an HUVEC;(c)HMSNs located in cytoplasm;(d)HMSNs endocytosed and collected by lysosome (N:nucleus;Nm:nuclear membrane;Cp:cyto-plasm;Cm:cell membrane;Mi:mitochondria;Ly:lysosome).Arrows in the image indicate the location of HMSN in the cells.Bar in (a)and (b)is 1l m,in (c)and (d)0.5l m.

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which were much less than that of the original HMSNs,indi-cating that HMSNs were undergoing degradation within the cytoplasm or lysosomes through gradual dissolution.After 4days of culture,HMSNs were degraded at higher extent than that after 2days of culture both in cytoplasm [Figure 4(c)]and in lysosome [Figure 4(d)].After 7days of culture,besides ?uorescent-labeled small HMSNs,low-density ?uo-rescence was observed in whole cytoplasm of the cells.indi-cating the release of FITC molecules and the degradation of HMSNs (Figure 5).

To quantitatively study the HMSN degradation,the Si content in cell culture medium was measured by ICP-OES and the result showed that cells excreted Si ions to the me-dium through the culture period with a fast release in the ?rst 2days and a slow release rate after 2days of culture [Figure 6(a)].Moreover,the accumulative Si content increased with the increase of the culture time [Figure 6(b)],indicating a continuous Si ion excretion from the cells.During the whole experiment period,all the silicon content outside the cells (in culture medium)was accumulated to 57.86l g,about 46.29%(57.86/125l g)of initial amount of HMSNs [Figure 6(b)].

To con?rm the degradation of the HMSNs in cells,at selected time point,the cells were digested using enzyme to release the degraded Si ions and small pieces of HMSNs.The samples centrifuged at 5600g for 1min and at 11,000g for 15min to yield two supernatant samples were referred as

lysates-5600g and lysates-11,000g ,respectively.The HMSNs without degradation and the big pieces of degraded HMSNs were excluded to the precipitation by centrifugation.The Si content in the supernatant of cell lysates represented the free Si ions or small pieces of the degraded HMSNs and was analyzed by ICP-OES.The result showed that the Si content in lysates-5600g fractions varied between 8.05and 11.40l g/mL,indicating that the HMSNs being decomposed into small pieces during the culture periods (Figure 7).The Si content in lysates-11,000g fractions varied between 6.25and 7.07l g/mL,showing that the amount of ?nal degradation product of HMSNs was almost constant either in cytoplasm or in lysosomes.The Si content in Lysates-5600g was found higher than that in lysates-11,000g at each time point.The explanation for this phenomenon is that the samples of lysates-5600g contained small pieces of HMSN,which con-tributed to the ionic Si when measured by ICP-OES.These small pieces could be further separated by higher speed cen-trifugation at 11,000g ,so that the Si content of lysates-11,000g was lower than that of lysates-5600g .

DISCUSSION

It is conceivable that after nanoparticles being intravenous injection,the cells,that ?rst in touch and interact with nanoparticles,might be the blood cells and vascular endo-thelial cells.In the present study,we demonstrated that HMSNs could be uptaken by HUVECs,and distributed in

the

FIGURE 3.The distribution of HMSNs in cells after 2days (a–d)and 4days (e–h)of culture.Images (a–d)showed that most of the HMSNs were located in the lysosomes of the cell.Images (e–h)show that all HMSNs were still accumulated in the lysosomes without any pieces of HMSNs being exocytosis.The green,red,and blue ?uorescence indicate HMSNs (a,e),lysosome (b,f),and cell nucleus (c,g),respectively.(d)The merged image from (c)and phase contrast micrograph of the cell,(h)from (g)and the phase contrast micrograph of the cell.Bar is 5l m.[Color ?gure can be viewed in the online issue,which is available at https://www.wendangku.net/doc/db10338426.html,.]

1400ZHAI ET AL.DEGRADATION OF HOLLOW MESOPOROUS SILICA NANOPARTICLES IN HUMAN CELLS

cytoplasm and lysosome,similar to the up-taking of other mesoporous SNps by HeLa cells 22,23,26and human mesen-chymal stem cells.25Here,HMSNs,being a special kind of mesoporous SNps,was for the ?rst time demonstrated to be degradable inside the cells.Figure 8shows a possible pro-cess accounting for HMSNs degradation in HUVECs.Recently,it was reported that mesoporous silica can be degraded in simulated body ?uid.32Therefore,it is specu-lated that HMSNs might be degradable,at some extent,in cytoplasm.This speculation was con?rmed in the present study by TEM observation,confocal microscope observation,and ICP-OES measurements.The original size of the

HMSNs

FIGURE 4.Degradation of HMSNs outside and within lysosomes in HUVEC after 2(a and b)and 4(c and d)days of culture.(a)HMSNs degrad-ing inside and outside lysosomes with the diameters <200nm after 2days of culture.(b)HMSNs degrading inside lysosome with diameters <200nm after 2days of culture.(c)HMSNs were degrading into small pieces in cytoplasm after 4days of culture.(d)HMSNs were degrading into small pieces which mixed with protein in lysosome after 4days of culture.Mi:mitochondrion;Ly:lysosome.White arrow heads showing HMSNs inside of lysosomes;Black arrows showing nondegraded HMSNs (outside lysosome in (a),inside lysosome in (b));black arrow heads showing small pieces of degraded HMSNs (degrading HMSNs)with the diameters <200nm;Bar in (a)is 1l m,in others 500

nm.

FIGURE 5.Partly degradation of FITC-conjugated HMSNs in cytoplasm of HUVECs after 7days of culture.(a)Two cells under bright ?eld;(b)The partly degraded FITC-conjugated HMSNs (green,indicated by red arrows)among numerous small pieces of degraded product;(c)The merged image from A and B.Bars ?20l m.[Color ?gure can be viewed in the online issue,which is available at https://www.wendangku.net/doc/db10338426.html,.]

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is in the range of 300–430nm.Based on TEM observation,the diameter of HMSNs was reduced to <200nm either in cytoplasm or in lysosomes during the culture period.The ICP-OES results further showed that the Si was detected in the supernatant of cell lysates and the accumulative Si con-tent continuously increased in culture medium.These data clearly demonstrated that HMSNs were degraded to small pieces by releasing or excreting Si ions out of the cells.Recent research has reported that a ?uorescent mesoporous SNps can also be endocytosed in cancer cells (HeLa),but the internalized particles seem to be mostly exocytosed from cells within 96h almost without degradation.28This result suggests that nanoparticle degradation inside the cells may partly depend on the cell type and probably partly depend on the particle nature.29

It is known that many kinds of hydrolytic enzymes resided inside the lysosome at low pH environment to digest the endocytosed substrates.30It was reported that this environment may result in cleavage of covalent bonds between the loaded drug and SNps,leading to the complete release of drugs.26Iron oxide nanoparticles have been shown to be solubilized in the absence of any enzymes at a pH similar to that found in endosomes and lysosomes.31But in the present study,the hydrolytic enzyme and the

acidic

FIGURE 6.The Si content in old medium refreshed from the cell cultures at different times (a)and the accumulative Si content (b)during differ-ent period.*p <0.05when compared with the value at day 0.[Color ?gure can be viewed in the online issue,which is available at

https://www.wendangku.net/doc/db10338426.html,.]

FIGURE 7.The Si content in cell lysates-5600g and cell lysates-11,000g during different periods.After 1day of culture,the Si con-tents were almost constant in lysates-11,000g during different periods.Lysates-5600g and lysates-11,000g :the supernatants of the cell lysates which were centrifuged at 5600g for 1min and at 11,000g for 15min,respectively.[Color ?gure can be viewed in the online issue,which is available at

https://www.wendangku.net/doc/db10338426.html,.]

FIGURE 8.Illustration of a possible process accounting for HMSNs degradation in HUVECs.[Color ?gure can be viewed in the online issue,which is available at https://www.wendangku.net/doc/db10338426.html,.]

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environment seemly had little effect on the HMSNs degrada-tion after being endocytosed in lysosomes as showed by laser scanning confocal microscopy,as the Si-content in lysates-11,000g from degraded HMSNs inside cells was rela-tively constant(Figure7).However,further experiments need to be designed to fully elucidate the process and the mechanisms of the HMSNs degradation.

The present result also showed that the degraded prod-uct can be excreted from the cells.The fast accumulation of Si content outside the cells in the?rst2days may be owing to the release of Si ions from the degraded HMSNs in cyto-plasm,which may be easily excreted through cytomem-brane.After2days of culture,the HMSNs were endocytosed in lysosomes(Figures3and4)and the degraded product had to defuse through the lysosome membrane,the cyto-plasm,and the cytomembrane to excrete.This process was much more complex and might result in a decrease of the Si accumulation after2days of culture.

Based on our experiments,HMSN is proved to be degradable in HUVEC?rst in cytoplasm and lysosomes and secondly only in lysosomes.The degradation product inside the cells can be excreted into the culture medium.The deg-radation rate is fast in the?rst2days and slowed down af-ter2days.Data from this investigation provide a clue for further study on the metabolic way and cytotoxicity of SNps as drug carrier or for diagnostic applications.Furthermore, the present results suggested that HMSN might be able to release loaded drugs inside cells through degradation. REFERENCES

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蛋白质的降解知识讲解

蛋白质的降解

第六章蛋白质的降解及其生物学意义 ?第一节蛋白质降解的概述 ?第二节参与蛋白质降解的酶类 ?第三节蛋白酶体-泛素系统及其功能 ?第四节蛋白质降解的生物学意义 蛋白质降解是生命的重要过程 ?维持细胞的稳态。 ?清除因突变、热或氧化胁迫造成的错误折叠的蛋白质，防止形成细胞内凝集。 ?及时终止不同生命时期调节蛋白的生物活性。 ?蛋白质的过度降解也是有害的，蛋白质的降解必须受到空间和时间上 蛋白质降解的体系 ?蛋白质消化分解为被机体吸收的营养物质。 ?研究蛋白质结构时，用蛋白酶降解肽链。 ?蛋白质新生肽链生物合成以及新生肽链折叠的过程中，质量的控制都与“次品”的降解有关。 ?蛋白质在行使功能时，很多调节控制都与肽键的断裂有关，如前肽的切除、无活性的前体蛋白质的激活等。 第一节蛋白质降解的概述 蛋白质的寿命 ?细胞内绝大多数蛋白质的降解是服从一级反应动力学。半衰期介于几十秒到百余天，大多数是70～80d。 ?哺乳动物细胞内各种蛋白质的平均周转率为1 ～ 2d。代谢过程中的关键酶以及处于分支点的酶寿命仅几分钟，有利于体内稳态在情况改变后快速建立。 –大鼠肝脏的鸟氨酸脱羧酶半衰期仅11min，是大鼠肝脏中降解最快的蛋白质。 –肌肉肌动蛋白和肌球蛋白的寿命约l～2w。 –血红蛋白的寿命超过一个月。 ?蛋白质的半衰期并不恒定，与细胞的生理状态密切相关。 蛋白质寿命的N端规则 ?N端规则：细胞质中蛋白质的寿命与肽链的N端氨基酸残基的性质有一定的关系。 ?N端的氨基酸残基为D、R、L、K和F的蛋白质，其半衰期只有2~3min。 ?N端的氨基酸残基为A、G、M和V的蛋白质，它们在原核细胞中的半衰期可超过10h，而在真核细胞中甚至可超过20h。 酿酒酵母蛋白质代谢特点 ?酿酒酵母中不稳定蛋白的N端氨基酸残基有12个： Asn（B）、Asp（D）、Glu（E）、Phe （F）、His（H）、Ile（I）、Leu（L）、Lys（K）、Arg（R）、Trp（W）、Tyr（Y）和Gln （Z）。 ?酵母中存在切除N端甲硫氨酸的氨肽酶，它作用的蛋白质底物的N端第二个氨基酸一定是N端规则中的氨基酸残基。 PEST假设 ?PEST（Pro-Glu-Ser-Thr）假设：认为含有序列为PEST肽段的蛋白质，在细胞质中很快被降解，在这个亲水的区域附近常有碱性残基。 ?PEST肽段的缺失，可以延长此突变蛋白质的寿命。 ?在22个快速降解的蛋白质中有20个是含有PEST序列。

观察植物细胞的基本结构

观察植物细胞的基本结构 与动物细胞比较，植物细胞的体积一般比动物细胞的体积大，但是植物细胞也不能直接在显微镜下观察，需要经过处理制成装片和切片标本，才能观察。【活动目标】 1．练习制作植物细胞临时装片； 2．用显微镜观察植物细胞的形态和结构； 3．练习绘制植物细胞结构图。 【材料器具】 洋葱鳞片叶、番茄果实、水绵装片、衣藻装片、蚕豆下表皮装片、其他植物玻片；清水、碘液、显微镜、载玻片、盖玻片、刀片、镊子、解剖针、干净纱布、吸水纸。 【方法步骤】 1．制作和观察洋葱表皮细胞临时装片 (1)用干净纱布将载玻片、盖玻片擦拭干净。 (2)在载玻片中央滴一滴清水。 (3)取一块洋葱鳞片叶的内表皮，置于载玻片的清水中，展平，盖上盖玻片，制成临时装片。 (4)在低倍镜下观察，可以看到的结构有（）。 在视野中选择一个清楚的细胞绘图记录如下，注明细胞结构的名称。 2．制作番茄果肉细胞临时装片 (1)用干净纱布将载玻片、盖玻片擦拭干净。 (2)在载玻片中央滴一滴清水。 (3)用解剖针在切开的番茄果实中挑取少许成熟的果肉，将果肉均匀地涂抹在载玻片的清水中，盖上盖玻片。 (4)在低倍镜下观察，可以看到番茄果肉细胞的结构有（）。 选择1～2个细胞，绘图如下： 番茄果肉细胞(绘图) 《构成植物体的细胞》教学设计

课题：构成植物体的细胞 教材分析： 本课教材是北师大版《生物学》七年级上，第3章第1节《细胞的基本结构和功能 》中的内容，本节主要是介绍细胞的基本结构和功能方面的知识。要了解细胞这样小的结构，必须借助一定的工具，因此显微镜的使用也是本节学习的重点内容。本节内容的设计是让学生在熟悉显微镜的过程中认识不同类型的细胞，发现不同类型的细胞形态结构的共同特点和不同特点，在此基础上进一步了解细胞的功能。本教案是第三课时《构成植物体的细胞》的教学设计。 教学目标： 1.知识目标： （1）区别植物细胞的基本结构。 （2）说明制作临时装片的基本方法步骤。 2.能力目标： （1）尝试自己制作临时装片。 （2）运用显微镜观察生物细胞

蛋白质的降解

第六章蛋白质的降解及其生物学意义 ?第一节蛋白质降解的概述 ?第二节参与蛋白质降解的酶类 ?第三节蛋白酶体-泛素系统及其功能 ?第四节蛋白质降解的生物学意义 蛋白质降解是生命的重要过程 ?维持细胞的稳态。 ?清除因突变、热或氧化胁迫造成的错误折叠的蛋白质，防止形成细胞内凝集。 ?及时终止不同生命时期调节蛋白的生物活性。 ?蛋白质的过度降解也是有害的，蛋白质的降解必须受到空间和时间上 蛋白质降解的体系 ?蛋白质消化分解为被机体吸收的营养物质。 ?研究蛋白质结构时，用蛋白酶降解肽链。 ?蛋白质新生肽链生物合成以及新生肽链折叠的过程中，质量的控制都与“次品”的降解有关。 ?蛋白质在行使功能时，很多调节控制都与肽键的断裂有关，如前肽的切除、无活性的前体蛋白质的激活等。 第一节蛋白质降解的概述 蛋白质的寿命 ?细胞内绝大多数蛋白质的降解是服从一级反应动力学。半衰期介于几十秒到百余天，大多数是70～80d。 ?哺乳动物细胞内各种蛋白质的平均周转率为1 ～2d。代谢过程中的关键酶以及处于分支点的酶寿命仅几分钟，有利于体内稳态在情况改变后快速建立。 –大鼠肝脏的鸟氨酸脱羧酶半衰期仅11min，是大鼠肝脏中降解最快的蛋白质。 –肌肉肌动蛋白和肌球蛋白的寿命约l～2w。 –血红蛋白的寿命超过一个月。 ?蛋白质的半衰期并不恒定，与细胞的生理状态密切相关。 蛋白质寿命的N端规则 ?N端规则：细胞质中蛋白质的寿命与肽链的N端氨基酸残基的性质有一定的关系。 ?N端的氨基酸残基为D、R、L、K和F的蛋白质，其半衰期只有2~3min。 ?N端的氨基酸残基为A、G、M和V的蛋白质，它们在原核细胞中的半衰期可超过10h，而在真核细胞中甚至可超过20h。 酿酒酵母蛋白质代谢特点 ?酿酒酵母中不稳定蛋白的N端氨基酸残基有12个：Asn（B）、Asp（D）、Glu（E）、Phe（F）、His（H）、Ile（I）、Leu（L）、Lys（K）、Arg（R）、Trp（W）、Tyr（Y）和Gln（Z）。 ?酵母中存在切除N端甲硫氨酸的氨肽酶，它作用的蛋白质底物的N端第二个氨基酸一定是N端规则中的氨基酸残基。 PEST假设 ?PEST（Pro-Glu-Ser-Thr）假设：认为含有序列为PEST肽段的蛋白质，在细胞质中很快被降解，在这个亲水的区域附近常有碱性残基。 ?PEST肽段的缺失，可以延长此突变蛋白质的寿命。 ?在22个快速降解的蛋白质中有20个是含有PEST序列。 ?在35个慢速降解的蛋白质中有32个不含PEST序列。 分泌到细胞外蛋白质的寿命 ?分泌到细胞外的蛋白质，它们的寿命都比较长，如胶原蛋白、眼睛中的晶体蛋白。

动物细胞基本结构

动物细胞 编辑 动物细胞立体结构图组成动物体的细胞称为动物细胞，植物细胞和动物细胞大体上相同，都有细胞核、细胞质和细胞膜。但是也有不同的地方：这就是植物细胞在细胞膜外面，有一层厚而坚硬的细胞壁，而动物细胞是没有细胞壁的；植物细胞中有扁球状的叶绿体．而动物细胞里没有这种结构，植物细胞中有囊状的液泡，而动物细胞里的液泡却不明显。 目录 1简介 2结构特征 3培养 4培养液的成分 5培养液的特点 6培养 7基本过程 8动植物组织培养区别 9动物细胞培养的应用 10相关词条 1简介 动物细胞立体结构图组成动物体的细胞称为动物细胞，人体或动物体的各种细胞虽然形态不同，基本结构却是一样的，都有细胞膜、细胞质和细胞核。 2结构特征

中心粒 核糖体 滑面内质网 高尔基小泡 高尔基体 微绒毛 核仁 细胞核 核被 粗面内质网 溶酶体 线粒体 质膜 滑面内质网 动物细胞有细胞核、细胞质和细胞膜，没有细胞壁，液泡不明显，含有溶酶体,动物细胞的结构有细胞膜、细胞质、细胞器、细胞核；它们的主要作用是控制细胞的进出、进行物质转换、生命活动的主要场所、控制细胞的生命活动。细胞内部有细胞器：细胞核，双层膜，包含有由DNA和蛋白质构成的染色体。内质网分为粗面的与滑面的，粗面内质网表面附有核糖体，参与蛋白质的合成和加工；光面内质网，表面没有核糖体，参与脂类合成。

3培养 细胞培养是指细胞在体外条件下的生长，动物细胞在培养的过程中不再形成组织。 概念：从动物机体中取出相关的组织，将它分散成单个细胞，然后放在适宜的培养基中，让这些细胞生长和增殖。 4培养液的成分 葡萄糖、氨基酸、无机盐、维生素和动物血清等。动物细胞培养成功的关键在于培养液中是否含有动物血清，因为由于动物细胞生活的内环境还有一些成分尚未研究清楚，所以需要加入动物血清以提供一个类似生物体内的环境，此外动物血清中也包含了一些动物的激素和酶，可以促进细胞的发育。 5培养液的特点 液体培养基、含动物血清。 6培养 .动物细胞培养液的成分：体外细胞培养所需营养物质与体内基本相同，例如，需要糖、氨基酸、无机盐、促生长因子、微量元素等。将细胞所需的上述物质按其种类和所需数量严格配制而成的培养基，称为合成培养基。由于动物细胞生活的内环境还有一些成分尚未研究清楚，所以需要加入动物血清以提供一个类似生物体内的环境，因此在使用合成培养基时，通常需加入血清、血浆等一些天然成分。 2.动物细胞培养液的特点：液体培养基、通常含动物血清。 3.动物细胞培养的条件： ①无菌、无毒的环境：对培养液和所有培养用具进行无菌处理，通常还要在培养液中加入一定量的的抗生素，以防被污染。此外应定期更换培养液，以便清除代谢产物防止细胞代谢产物累积对细胞自身产生危害。 ②营养物质：无机物（无机盐、微量元素等），有机物（糖、氨基酸、促生长因子等）。 ③血清和血浆(提供细胞生长必须的营养成份) 。 ④温度和pH（36.5±0.5℃，7.2~7.4）。 ⑤气体环境（95%的空气+5%CO 2的混合气体）。 其中5%CO2气体是为保持培养液的pH稳定。

真核细胞内蛋白质的降解途径

真核细胞内蛋白质的降解途径 作者:valley 日期:2009-3-9 11:13:00 1 推荐 真核细胞内蛋白质的降解途径主要有三种，溶酶体途径、泛素化途径和胱天蛋白酶(caspase)途径。 1、溶酶体途径：蛋白质在同酶体的酸性环境中被相应的酶降解，然后通过溶酶体膜的载体蛋白运送至细胞液，补充胞液代谢库。胞内蛋白：胞液中有些蛋白质的N端含有KFERQ信号，可以被HSC70识别结合，HSC70帮助这些蛋白质进入溶酶体，被蛋白水解酶降解。胞外蛋白：通过胞吞作用或胞饮作用进入细胞，在溶酶体中降解。 2、泛素-蛋白水解酶途径：一种特异性降解蛋白的重要途径，参与机体多种代谢活动，主要降解细胞周期蛋白Cyclin、纺锤体相关蛋白、细胞表面受体如表皮生长因子受体、转录因子如NF-KB、肿瘤抑制因子如P5 3、癌基因产物等；应激条件下胞内变性蛋白及异常蛋白也是通过该途径降解。该通路依赖ATP，有两步构成，即靶蛋白的多聚泛素化?多聚泛素化的蛋白质被26S蛋白水解酶复合体水解。 (1)、物质基础： 泛素(ubiquitin)：一种76个氨基酸组成的蛋白质，广泛存在于真核生物中，又称遍在蛋白。在一系列酶的作用下被转移到靶蛋白上，介导靶蛋白的降解。 蛋白水解酶(proteasome)：识别、降解泛素化的蛋白质的复合物，由30多种蛋白质及酶组成，其沉降系数为26S，又称26S蛋白酶体，由20S的圆柱状催化颗粒和19S的盖状调节颗粒组成，是一个具有胰凝乳蛋白酶、胰蛋白酶、胱天蛋白酶等活性的多功能酶。所有蛋白酶体的活性中心都含有Thr残基。经泛素化的底物蛋白可以被26S蛋白酶体的盖状调节颗粒识别，并被运送到20S的圆柱状核心内，在多种酶的作用下水解为寡肽，最后从蛋白酶体中释放出来。泛素则在去泛素化酶的作用下与底物解离后回到胞质重新利用。 (2)、具体过程： ①靶蛋白的多聚泛素化：泛素激活酶E1利用ATP在泛素分子C端Gly残基与其自身的半胱氨酸的SH间形成高能硫脂键，活化的泛素再被转移到泛素结合酶E2上，在泛素连接酶E3的作用下，泛素分子从E2转移到靶蛋白，与靶蛋白的Lys的ε-NH2形成异肽键，接着下一个泛素分子的C-末端连接到前一个泛素的lys48上，完成多聚泛素化(一般多于4个) ②多聚泛素化的蛋白质被26S蛋白水解酶复合体水解：经泛素化的底物蛋白可以被26S蛋白酶体的盖状调节颗粒识别，并被运送到20S的圆柱状核心内，在多种酶的作用下水解为寡肽，最后从蛋白酶体中释放出来。泛素则在去泛素化酶的作用下与底物解离后回到胞质重新利用。 3、胱天蛋白酶(caspase)途径：细胞凋亡的蛋白质降解途径。 Caspase的含义指该类蛋白酶的活性部位为极为保守的半胱氨酸(cysteine)及特异性切割底物的天冬氨酸(aspase),简称caspase。根据其具体功能分为调控caspase(caspase1,2,4,5,8,9,10)和效应caspase(caspase3,6,7,11)。 Caspase以酶原形式存在于正常细胞中，细胞凋亡启动后被激活。一条途径是由死亡信号分子和受体结合后的

实验一植物细胞的基本结构

实验一植物细胞的基本结构 类型：演示性 指导教师：张景景 一、目的与要求 1.掌握植物细胞的基本结构。 2.熟悉光学显微镜的构造、性能和使用。 3.学习表皮制片法及绘制植物细胞图的基本技巧。 二、实验原理 通过制作表皮临时装片，使用光学显微镜观察植物细胞的基本结构。 三、仪器与材料 1.仪器、用品：显微镜、镊子、刀片、解剖针、培养皿、载玻片、盖玻片、蒸馏水、吸水纸、稀碘液 2.材料：洋葱鳞茎、番茄果 四、方法与步骤 1.光学显微镜的使用和注意事项。 （1）使用：①取、放显微镜； ②对光； ③放置标本与调节； ④低倍镜的使用； ⑤高倍镜的使用； ⑥油镜的使用； ⑦用毕复原和存放。 （2）注意事项：①正确操作，自觉保养。

②不用手触摸光学镜面，不擅自拆卸。 ③观察时先低倍镜，后高倍镜。 ④上升或下降时，注意镜头不接触盖玻片。 2.洋葱表皮细胞和番茄果肉的制作。 ①拭擦玻片； ②载玻片中央加水滴； ③材料放入水滴并展平； ④盖盖玻片：用镊子夹起盖玻片，使盖玻片一边先放下，接触到水，然后再轻轻放平，以免产生气泡。 ⑤吸去多余水分：观察临时装片时一定要加盖盖玻片，并将其四周溢出的水擦干。 ⑥显微镜下观察。 3.观察植物细胞的基本结构：细胞壁、细胞质、细胞核、液泡。 4.植物显微构造绘图技术。 ①要求：科学性、真实感、精美、文字标注清晰。 ②基本步骤：其构图包括位置、结构特点、大小、比例等。 勾画轮廓； 用清晰的线条和圆点完成全图； 标注：引线、结构名称、图的名称、放大倍数。 注意：必须使用铅笔。 五、实验报告 绘出洋葱鳞叶的内表皮细胞2-3个，并注明细胞各部分名称。 六、分析与讨论

泛素调节的蛋白质降解

泛素标记的蛋白质降解 ——探索生命活动中化学过程的又一成果 李静雯陆真 （南京师范大学化学教育研究所南京 210097） 摘要：本文主要介绍了2004年诺贝尔化学奖--泛素调节蛋白质降解的原理、模型及应用实例。该成果将有助于科学家从分子水平对细胞控制蛋白质分裂进行研究，并有利于研发新型药物，从而造福人类。 关键词：2004诺贝尔化学奖泛素标记蛋白质降解 2004年10月16日瑞典皇家科学院将本年度诺贝尔化学奖授予以色列科学家阿龙·切哈诺沃、阿夫拉姆·赫什科和美国科学家欧文·罗斯，以表彰他们在泛素调节的蛋白质降解研究领域中的卓越成就。 图1 2004年诺贝尔化学奖获得者，从左至右依次为阿龙·切哈诺沃、阿弗拉姆·赫尔什科、欧文·罗斯 阿龙·切哈诺沃1947年出生在以色列城市海法，现年57岁，1976-1981年间在赫什科指导下攻读博士学位，1981年获得以色列工学院医学博士学位，曾在麻省理工学院从事研究，后返回以色列工学院任教；阿弗拉姆·赫尔什科1937年出生在匈牙利，犹太后裔，13岁移民以色列，现年67岁，1969年在耶路撒冷希伯来大学获得医学博士学位，曾在旧金山加州大学从事研究，1972年起在以色列工学院任教；来自美国的欧文·罗斯现年78岁，1952年在芝加哥大学获得博士学位，现就职于美国加利福尼亚大学欧文分校。三名获奖者自20世纪70~80年代以来就一直致力于这一领域的研究。1970年代末，赫什科借着带薪休假的机会，带着当时还是博士后的切哈诺沃，到美国费城福克斯·蔡斯癌症研究中心的罗斯实验室进行访问研究，在那里完成了三位获奖者的大部分合作研究，发表了一系列生物化学论文。 1 泛素调节的蛋白质降解的生物学概述 蛋白质是包括人类在内各种生物体的重要组成成分。对于生物体而言，蛋白质的生成与降解至关重要。过去几十年来，生物化学界对于细胞如何制造出各种蛋白质有很多解释，但是对蛋白质降解的研究还很少，上世纪80年代初期这三名学者深入蛋白质降解过程的研究领域，进而发现了细胞最重要的循环过程以及有规律的蛋白质降解活动。

植物细胞教案

第一章细胞是生命活动的基本单位第二节植物细胞 一、教学目标 （一）知识方面 1、举例说出玻片标本的基本类型 2、认识植物细胞的基本结构及其作用 二、能力目标学会制作植物细胞装片的基本方法 三、情感态度与价值方面 通过观看录像，掌握制作临时装片的全部过程 四、教学重点和难点 （一）教学重点 1、通过观看录像并学会制作临时装片 2、植物细胞的基本结构及其作用 （二）教学难点 未在亲自练习制作植物细胞临时装片，但必须要掌握临时装片的规范操作。 五、导入新课 通过提问问题（一颗草莓能放在显微镜的载物台上直接观察吗？）导入新课六、教学过程 （一）玻片的种类和组成师：一颗草莓能放在显微镜的载物台上直接观察吗？生：不能，只能观看“薄而通明”的标本，光线穿透标本才可以

师：那好，例如，皮肤、肠、血液、黄瓜、洋葱等物体怎样才能制成薄而透明的呢？生：需要切成薄片、撕下一块或涂抹。。。。师：好，同学们说了很多，那好，看看你们回答的正确吗？为了做到“薄而透明” 我们对材料进行处理，并制成玻片标本。 常用的有三种： 切片—用从生物体上切去的薄片制成（皮肤、肠。。）涂片—用液体的生物材料经涂抹制成（血液。。。）装片—用撕下或挑取的少量生物材料制成（黄瓜、洋葱。。。）根据玻片标本的保存期长短可以分为永久玻片（可长期保存）和临时玻片（不能长期保存）玻片标本由载玻片（托住标本的玻璃片）和盖玻片（覆盖标本的玻璃片）组成。 （二）制作并观察植物细胞临时装片 1、目的要求：制作植物细胞临时装片, 学习制作临时装片的基本方法。认识植物细胞的基本结构。 练习画细胞结构简图。2、制作洋葱鳞片叶内表皮细胞临时装片（重点）材料用具 洋葱鳞片叶，新鲜的黄瓜，苦草（黑藻），清水，碘液，镊子，刀片，滴管，纱布，吸水纸，载玻片，盖玻片，显微镜 方法步骤（擦、滴、取、展、盖、染、吸） 1）擦——用洁净的纱布把载玻片和盖玻片擦拭干净。 （注意：顺一个方向擦，不能来回擦拭） 2）滴——把载玻片放在实验台上，用滴管在载玻片的中央滴一滴清水。（目的：保持材料新鲜，保持细胞形状。） 注意：一滴水要适量不能过多，水多容易污染显微镜，水少了易产生气泡）3）取一一用镊子从洋葱鳞片叶内侧撕取一小块透明薄膜一一内表皮。 （注意：大小为0.5cm X 0.5cm ） 4）展——把撕下的内表皮浸入载玻片上的水滴中，用镊子把它展平。

七年级生物上册 细胞的基本结构和功能动植物细胞的结构及区别课后习题北师大版

第2课时动植物细胞的结构及区别 知能演练提升 能力提升 1.制作人体口腔上皮细胞临时装片时,取材前漱口的目的是( ) A.清洁口腔上皮细胞 B.清除口腔中的食物碎屑 C.使上皮细胞容易刮取 D.以上都不正确 2.采几片红色苋菜叶放入盛有少量清水的烧杯中,加热至沸腾,可见杯中的水变成了红色。这种红 色的色素主要来自苋菜细胞的( ) A.细胞膜 B.细胞质 C.细胞核 D.液泡 3.植物细胞一般具有立方体或多面体的形状,这是因为植物细胞具有( ) A.细胞质 B.细胞膜 C.液泡 D.细胞壁 4.制作口腔上皮细胞临时装片时,在载玻片中央滴一滴生理盐水,其作用是( ) A.保持细胞的正常形态 B.使细胞皱缩 C.使细胞涨破 D.离散口腔上皮细胞 5.显微镜视野内可以看清洋葱鳞片叶表皮细胞的细胞壁和细胞核,但看不清液泡。为了能显示细胞质与液泡的界面,可以换用( ) A.凹面反光镜和较大光圈 B.平面反光镜和较大光圈 C.凹面反光镜和较小光圈 D.平面反光镜和较小光圈 6.在显微镜下观察成熟的植物细胞,会发现许多细胞核不在细胞的中央,而是位于细胞的一侧。造 成这种现象的原因是( ) A.细胞质的流动 B.细胞的分裂 C.细胞核的活动 D.液泡的挤压 7.在制作洋葱表皮细胞临时装片时,正确的做法是( ) A.尽量将标本撕得薄一些 B.盖上盖玻片后可直接将稀碘液滴在盖玻片上 C.若有气泡,则用手轻压赶走 D.将盖玻片垂直于载玻片后迅速放下

8.某同学在观察口腔上皮细胞临时装片时,发现视野中的细胞有重叠现象,不易观察。此时,他可采取的方法是( ) A.换用高倍目镜或物镜重新观察 B.移动装片,寻找合适的观察视野 C.选用较小的光圈和平面反光镜 D.换凹面镜并稍微调节细准焦螺旋 9.(2018·山东淄博中考)小刚同学欲使用显微镜判断某临时装片取材于动物还是植物,则( ) A.对光时,应使用高倍物镜迅速找到视野 B.观察时,应使用粗准焦螺旋使镜筒缓慢下降,直到看清物像 C.若发现细胞中有细胞壁,该装片一定取材于植物 D.若未发现细胞中有叶绿体,该装片一定取材于动物 10.某校七年级学生小强制作了人的口腔上皮细胞临时装片和洋葱鳞片叶表皮细胞临时装片,在显微镜下看到的情况如下图所示,据图回答下列问题。 (1)小强所观察到的人的口腔上皮细胞与洋葱表皮细胞具有细胞膜、细胞核、细胞质等共同结构,但也观察到人的口腔上皮细胞不具有、液泡和叶绿体等结构。 (2)制作人的口腔上皮细胞临时装片的主要步骤:擦拭载玻片和盖玻片,滴生理盐水,用消毒牙签刮口腔内侧壁,涂抹,盖盖玻片,染色。图A中出现气泡,是由制作临时装片步骤的 “”操作不规范引起的。 (3)已知小强观察图B使用的目镜是5×,物镜是10×,则该物像被放大了50倍。若想在视野中观察到更多的细胞,小强应选择物镜放大倍数为(填“8×”“10×”或“15×”)的镜头,转动图C显微镜中标号所示结构更换物镜,进行观察。 探究创新 11.根据“观察人的口腔上皮细胞”实验,回答下列问题。 (1)在准备本实验的材料用具时,不需要准备图1中的(填标号),还需要添加的材料用具有。 图1 图2 (2)观察时如果视野过亮,除了调节显微镜的光圈外,还可以调节哪一结构?请在图1的显微镜上标注该结构的名称。 (3)图2是某同学所绘的人体口腔上皮细胞结构图,请你指出图中存在的错误或不妥之处。

观察动植物细胞(实验报告)

实验二观察动物细胞和植物细胞 一、实验目的 1.练习使用显微镜和制作临时装片； 2.进一步认识细胞的基本结构并了解动植物细胞的区别； 3.学习如何绘制生物显微图。 二、实验原理 实验室常用的光学显微镜是根据凸透镜成像的原理制成的，因此使用光学显微镜时光必须能透过物体，才能利用显微镜进行观察。因而在制作装片时，被观察的物体必须薄且透光。 三、实验器材 显微镜、载玻片、盖玻片、镊子、滴管、牙签、吸水纸、纱布、刀片、水、红墨水（或碘液）、0.01%亚甲基蓝溶液、0.9%的生理盐水、洋葱鳞片。 四、实验步骤（补充步骤）和结果记录 （一）观察洋葱表皮细胞 1.擦：___________________________________________________________ _____ 2.滴：___________________________________________________________ _____ 3.撕：

_____ 4.展：___________________________________________________________ _____ 5.盖：___________________________________________________________ _____ 6.染：___________________________________________________________ _____ 7.观察 （1）将在显微镜下观察到的洋葱表皮细胞绘制在下面的空白框内，画图时注意如下几点：将结构图画在中部偏左部分，在标注细胞中的结构时，需用尺引出水平线，并将相应的结构名称标注在线的右边；画图时只能采用点、线、面，明暗部分用铅笔点出疏密不同的细点表示；最后在结构图下方标注所画图形的名称（如洋葱表皮细胞）

动植物细胞的结构

专题复习二 细胞的基本结构和功能 （第2课时：动植物细胞的结构） 中考提纲：（1分钟） 1 人体口腔上皮细胞临时装片的制作：擦→滴→刮→涂→盖→染。 2 洋葱表皮细胞临时装片的制作：擦→滴→撕→展→盖→染。 3 动植物体细胞结构的比较：植物细胞特有的结构是：细胞壁、液泡、叶绿体复习目标（1分钟） 1 动植物细胞各部分结构名称和功能。 2 如何制作人体口腔上皮细胞临时装片。 3 如何制作洋葱表皮细胞临时装片。 4 比较动植物细胞的结构。 复习指导一 看课本的P36-45页，掌握下列知识点。（7分钟） 1 制作口腔上皮细胞临时装片的过程是怎样的？ 2 怎样制作洋葱表皮细胞临时装片？ 3 在以上试验中，要注意哪些注意事项？ 4 动植物细胞之间有哪些主要的区别？ 复习检测一（8分钟） 1．生物体的结构和功能的基本单位是( ) A．细胞B．组织C．器官D．系统 2．下列除哪项外其他都是单细胞生物( ) A．衣藻B．草履虫C．变形虫D．玉米 3．当你发现显微镜镜头不清洁时，除去污物的正确方法是( ) A．用纱布擦B．用手擦C．用纸巾擦D．用擦镜纸擦 4．制作人的口腔上皮细胞装片时，滴加0．9％的生理盐水的目的是( ) A．杀菌观察效果好B．易盖盖玻片

C ．易染色 D ．维持细胞的正常形态 5．制作口腔上皮细胞时，漱口的目的是( ) A ．清除口臭 B ．冲刷下口腔上皮细胞 C ．清除口腔中的食物残渣 D ．防止口腔发炎 6．在低倍镜下看到的人口腔上皮细胞是( ) A ．方形 B ．扁平圆形 C ．立方形 D ．圆柱形 7．制作洋葱表皮细胞临时装片时，正确的盖盖玻片的方法是( ) A ．将盖玻片的一边先接触载玻片上的水滴，然后轻轻盖上 B ．将盖玻片的一边先接触载玻片上的水滴，然后快速盖上 C ．将盖玻片放在载玻片上，推向中央 D ．将盖玻片迅速盖在载玻片上 8．在植物细胞中，控制物质出入细胞的结构是( ) A ．细胞膜 D ．细胞壁 C ．细胞质 D ．细胞液 9．动物细胞同植物细胞明显的区别是( ) A ．呈圆形 B ．有细胞间质 C ．没有细胞壁 D ．细胞形态差别很大 10．下列结构属于植物细胞特有的是 ( ) A ．细胞膜 B ．细胞质 C ．细胞核 D ．叶绿体 11．右图是植物细胞的结构图，请据下图回答： (1)写出图中各结构的名称： ①_________；②_________； ③_________；④_________； ⑤_________；⑥_________。 (2)图中对细胞起保护和支持作用的结构是 __________________；含有遗传物质的是 _________； 能进行光合作用的是_________。 (3)盐腌黄瓜丝溢出的黄瓜汁水主要来自细胞结构中的_________。 (4)动物细胞没有图中的_________。 12 ．下图是“制作洋葱鳞片叶表皮细胞临时装片”的部分操作示意图，请回答： (1)用字母和箭头写出正确的操作顺序_________。 (2)B 中滴的是_________，目的是_________。 ① ② ④ ⑥ ⑤ ③