《《家装电工基础知识》PPT课件》由会员分享，可在线阅读，更多相关《《家装电工基础知识》PPT课件（74页珍藏版）》请在金锄头文库上搜索。
1、第四节溶酶体和过氧化物酶体溶酶体（lysosome）的发现较晚，首先是由ChristiandeDuve(1955)发现的。在溶酶体中含有丰富的水解酶，现已知，所有的动物细胞（特化的红细胞除外）内都含有溶酶体；植物细胞中也发现有类似溶酶体的圆球体结构东莞电工培训 Plant cell vacuoles.光镜下的内皮细胞：绿色荧光定位溶酶体红色显示线粒体由高尔由高尔基复合基复合体成熟体成熟面的扁面的扁平囊形平囊形成有被成有被小泡，小泡，脱落后脱落后再与内再与内体合并体合并即为内即为内体性溶体性溶酶体。酶体。当内体性溶酶体与细胞内衰老当内体性溶酶体与细胞内衰老的细胞器或由细胞胞吞作用摄入的细胞器或由
2、细胞胞吞作用摄入的外来物质融合后便形成吞噬性的外来物质融合后便形成吞噬性溶酶体。溶酶体。An electron micrograph showing two small lysosomes and one large lysosome. These organelles contain enzymes capable of breaking down various substances.一溶酶体的结构类型LL的不同生理阶段可分为(1)初级溶酶体或原溶酶体（primarylysosome）或无活性的溶酶体。(2)次级溶酶体当初级溶酶体与来自细胞外部或细胞内部的物质相互作用时，就称为次级溶酶体（
3、secondarylysosome）。次级溶酶体又有不同的名称，体与固体物质作用或与吞噬泡相互作用所形成的次级溶酶体又称为吞噬溶酶体（phagolysosome）。如果初级溶酶体与液体物质或胞饮小泡相互作用因此这种次级溶酶体又称为多泡小体(multivesclarbody)。次级溶酶体也被称为消化泡。如以被消化的物质是外源或是内源的也可将次级溶酶体分为两种形式，一种是异体吞噬泡（heterophagicvacuole）,它作用的物质来自于细胞外；一种是自体吞噬泡（autophagicvacuoles），它作用的底物是细胞内的垃圾，如一些细胞器的残片。初级溶酶体次级溶酶体残余小体A summar
4、y of the autophagic pathway.A summary of the phagocytic pathway .The endocytic pathway.(3)在溶酶体内剩下一些不能分解的残渣物质，这时的溶酶体称为残留小体（residualbody）或称三级溶酶体(tertiarylysosome）。残留小体有些可通过外徘作用排出细胞,有些则积累在细胞内不被排出，形成一些固定的细胞内结构。如：脂褐质，常见于神经细胞和心肌细胞之中，为形状不规则，被单位膜包围的小体；其内容物电子密度较高。老年斑的形成老年斑的形成Colorized scanning electron micro
5、graph of a cell ingesting a synthetic particle.Phagocytosis.溶酶体膜的特点:(1)有质子泵HHH氢离子浓度比细胞质中高出100倍HHHHHH(2)具有多种载体蛋白将水解产物向外运转(3)膜蛋白高度糖基化溶酶体的特征酶是酸性磷酸酶.酶的最适PHPH是7.0左右.二溶酶体的功能1清除胞内和体内的垃圾由于溶酶体中含有丰富的水解酶，因此，细胞内许多的分解作用都可以由这些水解酶来完成。把溶酶体在细胞内分解各种物质的过程叫溶酶体的消化作用。因此，溶酶体也是细胞内的“消化器官”。对于细胞来说，不是所有的物质的分解都通过溶酶体进行的。高等动物组织的细
6、胞，大部分的小分子营养物质是通过细胞膜从血液内吸收进入细胞；一些分子量大的不能直接通过细胞膜的物质，是由内吞作用形成吞噬泡或胞饮泡进入细胞内。进入细胞的大分子物质及外面所包被的膜结构，与初级溶酶体接近并融合，溶酶体内的水解酶开始作用，分解大分子物质成小分子物质，即进行消化作用2防御功能L的防御功能主要体现在几种吞噬泡中.如,位于肝脾等血通道.(1)吞噬清除抗原抗体复合体(2)吞噬细菌病毒等.(3)机体感染发炎部位巨噬细胞的吞噬作用.死细胞的清除主要是由巨噬细胞完成.巨噬细胞的L非常多,L的酶协同过氧化氢等强氧化剂共同作用杀死细菌.由于巨噬细胞较多的吞噬作用,所以也可以看到巨噬细胞中有较多的残余
7、小体.这可能导致巨噬细胞的短寿.3L的其他生理功能.(1)作为消化器官为细胞提供营养(2)在分泌腺细胞中,参与分泌过程的调节如分泌细胞吞噬储存在腺体内腔的甲状腺球蛋白,吞噬泡与L融合,甲状腺球蛋白被水解成甲状腺素,然后分泌到细胞外的毛细血管中(3)两栖类发育蝌蚪尾巴的退化(4)受精作用精精子子形形成成模模式式图图The acrosomal reaction during sea urchin fertilizationAcrosomalprofilacin The cortical reaction during sea urchin fertilization三L的发生Gol中的磷酸转移酶是
8、如何在ER向G转送众多的蛋白质中识别溶酶体酶蛋白?现在知道溶酶体酶蛋白存在识别信号研究表明这一信号不是一段肽链而是依赖于构象的信号区(signalpatch)186。Secretarylysosome1871granzyme2不依赖M6PLysosomesinHealthandDiseaseIfthecelldoesnotproduceacertainlysosomalenzymeorifanenzymeisnotproperlyaddressedintheGolgiapparatus,alysosomalstoragediseasecanresult.Thesediseasesarecaus
9、edbyamassiveaccumulationofmaterialthatshouldhavebeendigestedinthelysosome.The sorting of lysosomal enzymes in a normal cell (left). First, enzymes receive a chemical address label in the Golgi apparatus (a) and move in vesicles (b) to a lysosome (c). Any enzyme that is accidentally swept out of the
10、cell (d) is recaptured and taken back to the lysosome (e). If some part of the process goes awry, a lysosomal storage disorder can result. For example, in Hurlers syndrome (center), an enzyme is not produced (f), and the lysosome therefore lacks that enzyme (g). If correctly tagged enzyme is added t
11、o the cells in test tubes (h), the cells can capture the enzyme and take it to the lysosome (i). In I-cell disease (right), enzymes are correctly made, but they are not tagged in the Golgi (j), and therefore are not sent to the lysosome. When such enzymes leave the cell (k), they cannot be recapture
12、d (l) and so the lysosome remains empty (m). 小儿致死遗传性疾病-台-萨氏病神经节苷脂-GM2-在神经细胞中GM2比较多在正常情况下GM2的代谢如下:水解神经节苷脂GM2需要氨基己糖脂酶A水解神经节苷脂GM2D的氨基己糖脂酶A缺失Lysosomal storage disorders.这样在神经细胞特别是脑细胞中GM2就会积累起来,最后造成精神呆滞,小儿在4-6岁时就会夭折.这类疾病被称为储积症,共有几十种,是一种隐性的遗传病.PersonswiththelysosomalstoragediseaseknownasHurlerssyndrome,fo
13、rexample,cannotbreakdownlargemoleculesofsugarcompoundscalledglycosaminoglycansbecausetheirlysosomesdonotcontaintheenzymeiduronidase.Glycosaminoglycansaccumulateinthelysosomes,swellingthemsomuchthatthefunctioningoftheentirecellisimpaired.Hurlers syndrome also called GARGOYLISM, ,脂质软骨营养障碍 OR MUCOPOLYS
14、ACCHARIDOSIS I,黏多糖(贮积)病(指任何一种涉及黏多糖先天性代谢紊乱的疾病) one of several rare genetic disorders involving a defect in the metabolism of mucopolysaccharides, the class of polysaccharides ，that bind water to unite cells and to lubricate joints. Onset of the syndrome is in infancy or early childhood, and the disea
15、se occurs with equal frequency in both sexes. Affected individuals exhibit severe mental retardation, clouding of the corners of the eyes, deafness, hirsutism (hairiness), enlarged liver and spleen, dwarfism with hunched back, short limbs and clawed hands, a large head with wide-set eyes, heavy brow
16、 ridges and deep bridge of nose, and poorly formed teeth. The disorder is identifiable within two years of birth; such children require institutional care and usually do not live beyond adolescence. Death most often results from heart failure, which is attributable to infiltration of heart muscle and coronary vessels with mucopolysaccharides.AparticularlyseverelysosomaldisorderisknownasI-celldisease.Childrenbornwiththisdiseaselacktheentirerangeoflysosomalenzymes.Theenzymesaremade,buttheyaredumpe
