第一章-原核微生物的形态结构和功能220.ppt

单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,*,单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,*,单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,*,单击此处编辑母版标题样式,*,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,*,Prokaryotes and eukaryotes,major differences,section A,Within the microbial world can be found two different categories of cell type/prokaryote and eukaryote.,DNA free in the cytoplasm,Only one chromosome,DNA associated with histone-like proteins,May contain extrachromosomal elements called Plasmids,Introns not found in mRNA,Cell division by binary fission-asexual replication only,Transfer of genetic information occurs by conjugation,transduction and transformation,DNA is contained with a membra-ne bound nucleus.A nucleolus is,also present,1 chromosome.Two copies of,each chromosome may be present(diploid),DNA complexed with histone,proteins,Plasmids only found in yeast,Introns found in all genes,Cells divide by mitosis,Exchange of genetic information,occurs during sexual reproduction.,Meiosis leads to the production,of haploid cells(gametes)which can fuse,原核生物和真核生物遗传的和细胞组装上的主要差别,DNA在细胞质中游离,只有一个染色体,DNA与类组蛋白连系,含有染色体外的遗传物质，称为质粒,在mRNA中没有发现内含子,细胞分裂以二等分裂方式，只有无性繁殖,遗传信息传递可通过接合、转导、转化发生,DNA在膜包围的核中，只有一个核仁,多于一个染色体，每个染色体是双拷贝(双倍体),DNA与组蛋白连系,只在酵母中发现质粒,所有基因中都发现内含子,细胞分裂为有丝分裂,遗传信息交换发生在有性繁殖过程，减数分裂导致产生,单倍体细胞(配子)，它们能融合,.原核生物.,真核生物,遗传物质的组装和复制,6.Cytoskeleton of microtubules present,7.Flagella have a complex structure with 9+2 microtubular arrangement,8.Ribosomes 80s(mitochondrial and chloroplast ribosomes are 70S),9.Polysaccharide cell walls,where present,are generally either cellulose or chitin,质膜含有hopanoids、脂多糖和磷壁酸,能量代谢与细胞质膜连系,光合作用与细胞质中膜系统和泡囊连系,由一根蛋白鞭毛丝构成鞭毛,核糖体70S,肽聚糖的细胞壁(只有真细菌有，古细菌中是不同的,多聚体),质膜含有固醇,多数情况在线粒体中发生,藻类和植物细胞中存在叶绿体,蛋白质合成和定向运输与内膜、粗面内质网及高尔基体有关,有膜囊泡如溶酶体和过氧化物酶体有微管骨架,核糖体-80S，细胞壁多糖一般是纤维素或者是几丁质,细胞组装,真核生物,原核生物,Rough ER,Golgi,mitochondria,Choloroplast,Cell wall of eukaryote,细胞核示意图,Nuclear spore,chromatin,cytoskeleton,一切真核细胞都有一套由蛋白质丝组成的细胞内部骨架。它不仅有助于细胞内部活动的条理化，并且是细胞运动及形态变化的基础。,Cytoskeleton of cultured cell,肌动蛋白丝,微管,中间丝,当一个细胞分裂时，其核膜被解离，且其DNA浓集成可见的染色体对，它们被微管拉开至两个分裂的自细胞中，微管从分裂细胞相对的两极会聚点辐射出去。,一个正在分裂的细胞中的微管,Lysosomea kind of organelle in animal cell,A comparison of the main features of these two categories of cell is shown in the table discussed,but other differences do occur.Although the basic mechanisms of DNA replication，RNA synthesis and protein synthesis are the same in both prokaryotes and eukaryotes,there are differences in the components and enzymes involved.These are discussed in the appropriate topics.,Major groups of prokaryotes,bacteria,actinomyces,Cyanobacteria,Spirochetes,others,Rickettsia,Chlamydia,Mycoplasmas,杆菌,原核生物常见种类和常见形态（1）,球菌,原和生物常见种类和常见形态（2蓝细菌（螺旋藻）,蓝细菌（鱼腥草）,原和生物常见种类和常见形态（3）,古细菌（产甲烷细菌）,细菌（耶尔森鼠疫杆菌）,Bacteria are small(1um-50um width/diameter),single-celled,microorganisms that belong to a group called prokaryotes so classified because their DNA is not enclosed within a nuclear membrane.,definition,Section B bacterium,Because they lack：a distinct nuclear membrane,the organelles associated with energy generation,such as mitochondria and chloroplasts,and complex internal membranes,such as endoplasmic reticulum and Golgi apparatus,which are found in eukaryotes.,Why bacteria are prokaryotes?,They are a highly successful and diverse group of organisms that can obtain energy and carbon from a wide range of sources and therefore can colonize（定居）every niche on our planet from deep ocean trenches to volcanic craters.,Bacteria are ubiquitous,In the 1970s,using DNA sequencing information,it was found that the group we know as the bacteria could be split into two,the eubacteria(Gr.,eu,true and,bakterion,a small rod)and the archaebacteria(Gr.,Archaios,ancient)and it appears that these two groups evolved away from each other very early in the history of living things at about the same time that the first group of eukaryotic cells evolved.（,是一个在进化途径上很早就与真细菌和真核生物相互独立的生物类群,）,1.eubacteria and archaebacteria,On the basis of 16S RNA sequences,it is now clear that there are(at least)three domains of organisms,the two prokaryotic groups,archaebacteria and eubac-teria and the eukarya,(Fig,).Within the eubacteria there are at least 11 groups,referred to sometimes as phyla,which can be represented on a phylogenetic tree.What can be seen is the wide diversity within the bacterial world and that may be familiar to us such as E.Coli,bacillus species are located within just a few of these phyla.It should be noted that the number of phyla will increase as more bacteria from diverse habitats are sequenced.,An overview of the phytogeny of the living world,showing the three major domains of organisms:the Eubacteria,the Archaebacteria and the Eukarya.,a Members of the eubacteria include some of the more familiar bacteria such as,Escherichia coli,and,Staphilococcus aureus,and are the prokaryotes that are best studied and understood.,The archaebacteria are a very diverse group of organisms,which differ from the eubacteria in a number of features havi-ng,in particular,very different cell walls and membranes.This group includes bacteria that are capable of existing in extreme environments,such as hot springs(examples:,Sulfolobus,and,Pyrococcus),and high salinity,(Halobacterium),and the methanogens such as,Methobacterium,which produce methane as a result of metabolism.主要包括一些独特生态类型的原核生物，如产甲烷菌及大多数的嗜极菌（extremophile），包括极端嗜盐菌、极端嗜热菌和热原体属（,Thermoplasma,）,古细菌（产甲烷细菌）,A list of the types of characters used to distinguish between bacteria is given below.This is not an exhaustive list and equally not all characters are used in either the classification or identification of every bacterial species.In many cases of well known microorganisms,a small set of tests may be all that is required to identify a microbe positively,especially if the site from which it has been isolated and the disease it caused are known.,Characters used in bacterial identification,A comma-shaped.Gram-negative rod isolated from a patient excreting copious amounts of straw-colored,liquid stools may be enough to identify it putatively as,Vibrio cholera,the causative agent for cholera.However,it may be necessary to do a wide range of tests to determine the name of an isolate if it is an undescribed microbe.,The shape,texture and color of bacterial colonies can be distinctive.For example,Staphylococcus aureus,is so named as colonies are of a yellow color;,aureus,comes from the Latin for golden.,1.Colony morphology.,Whether bacteria are Gram-positive or Gram-negative is one of the most important clinical diagnostic tests.Gram staining and microscopic examination of bacteria give information as to the shape,size and arrangement of the bacterial cells and in some cases this is enough to identify certain genera such as Streptococci which are Gram-positive cocci that grow in chains.Stains may also be used to show other morphological features,which may be used for classification,such as the presence of:,spores(malachite green stain);,unusual cell walls(Ziehl Neelsen acid-fast stain);,capsules(Indian ink stain);,intracellular lipids(Sudan black);,flagella(flagellar stain);,metachromatic granules(Albert-Leybourne stain).,2.Cell shape,structures and reaction to stains,The temperature,pH and 0;requirements of an isolate are useful tests for the identification of bacteria.,3.Growth characteristics.,There is a wide range of tests available that measure various aspects of bacterial metabolism:,what carbon and nitrogen sources the bacteria can use;,the end products of their metabolic processes,such as acetoin,tested for in the Vogues-Proskaeur test;,what enzymes the bacteria produce,such as decarboxylases,proteases and DNases;,the presence of other molecules such as toxins,long-chain fatty acids or antibiotics.,Biochemical tests,Antibodies to cellular components such as the 0-side chains of lipopolysaccharide(LPS)(Topic D3)or capsules are frequently used to distinguish between strains of one species.,Immunological tests,Comparisons of DNA content and sequence between strains are the most definitive methods for separating organisms into different groups and for measuring the evolutionary relatedness between them(phylogenetic analysis).Traditionally,DNA was analyzed by measuring the G-C content or the amount of DNA homology between strains.More recently,the comparison of the actual DNA sequences of conserved cellular molecules such as 16S ribo-somal RNA or proteins such as cytochrome C,ATPase and elongation factor has been used.This information has been analyzed by a technique called cladistics to trace true phylogenetic lineages that have not been obscured by patterns of convergent evolution.,DNA tests,The main impetus for bacterial classification has been the need to be able to identify bacterial disease-causing organisms and therefore these microbes are particularly well classified.However,it should be remembered that many other species have not been well characterized and many have not been isolated or described at all.The authority on bacterial classification is,Bergeys Manual of Systematic Bacteriology,which contains as near as possible complete listings of all prokaryotic species and their distinguishing characteristics.,Classification of bacteria,ranked are,sequentially,family,order,class,division and kingdom,though the final three are not particularly useful in bacteriology.Similarly,species may be divided into subspecies and a culture of a particular organism is usually referred to as a strain.Strain is also used to describe a sub-group of a species that share some feature such as one type of 0-antigen or mutation.There are also informal names,not italicized,which are sometimes useful for describing groups of organisms such as the green-sulfur bacteria or the spiro-chetes.,Classification of bacteria,In spite of this simplicity in structure there is a large amount of variation in the appearance of the cells when observed under the microscope.Two shapes of cell predominate,the coccus(spherical)and the bacillus,or rod,but there are also a wide range of other shapes(morphologies),2.Bacterial shapes,2.1,Individual shapes,Organization of cells Examples,Cocci,In chains,Streptococcus,spherical bacteria In grape-like clusters,Staphylococcus,In pairs(diplococci),Neisseria,In cubes of cells(packets),Sarcina,single,Micrococcus ureae,（1）coccus,球菌(coccus),脑膜炎奈瑟菌,双球菌(diplococcus),肺炎链球菌,链球菌(streptococcus),球菌(coccus),球菌(coccus),葡萄球菌(streptococcus),球菌(coccus),四联球菌(tetrad),球菌(coccus),八叠球菌(sarcina),杆菌,(,bacillus,),不同杆菌的大小、长短、粗细很不一致。,炭疽芽胞杆菌 3-10 m,大,中,大肠埃希菌 2-3 m,小,布鲁菌 0.6-1.5 m,杆菌的形态多样,杆菌,(,bacillus,),两端齐平,炭疽芽胞杆菌,两端尖细,白喉棒状杆菌,杆菌,(,bacillus,),杆菌的形态多样,分枝杆菌,双歧杆菌,螺形菌,(,spiral bacterium,),弧菌,螺菌,螺杆菌,化脓性链球菌,Streptococcus pyogenes-coccoid prokaryote;causes pharyngitis,sinusitis,otitis media(middle ear infection),food poisoning,puerperal fever(childbed fever),skin and wound infections(scarlet fever,erysipelas,impetigo).Group A strep.SEM x56,000,粪链球菌,Streptococcus faecalis-coccoid prokaryote;a pathogen causing skin and wound infections,链球菌,Rods/bacilli-rods may be very short(cocci-bacilli)or long,Singly,Pseudomonasa,In filaments of attached cells,Bacillus,sp,.,Most bacteria used in industry are bacillus,Bacillus subtilis to produce.amylase and protease,Coroynebacterium pekinense used for glutamic acid,Lactobacillus bulgaricus used in milk industry,（2）bacillus,结核杆菌,Mycobacterium tuberculosis.Rod-shaped Bacterium(SEM x40,000),白喉杆菌,Corynebacterium diphtheriae.Rod,clubed-shaped Bacterium(causes diphtheria),Plastic kitchen cutting board surface-rod bacteria in a smooth matrix;filamentous bacteria(丝状菌)-smooth oval cells;fungal hyphae(真菌菌丝)with textured spores(结构孢子)(x 2,270),Rod-Shaped Bacterium,E.coli (SEM x22,245)E.coli(0157:H7)-a rod prokaryote.Hemorrhagic type,痢疾杆菌,Shigella sonnei-rod prokaryote;causes shigellosis(bacterial dysentery)(x 22,400),伤寒杆菌,Salmonella-rod prokaryote;note the flagella.Causes salmonellosis(food poisoning).(x 20,800),大肠杆菌,棒状杆菌,肠杆菌,Comma shaped-called a vibrio,Vibrio,Spirillum-long,curved,rigid rods,Rhodospirillum,A Tightly coiled flexible bacteria spirochaetes,Treponema,柔软易曲的紧螺旋 如：密螺旋体属,Rhodospirillum 疏螺旋体属Borrelia,B Appendaged-cells have stalk or tube-like extensions 如红微菌属,Rhodomicrobium,C Pleomorphic-bacteria vary in shape,如棒杆菌属,Corynebacteria,D Branching mycelium-like filaments,Streptomyces,（,3）spirillum and vibrio,（4）others,霍乱弧菌 Vibrio cholerae-vibrio-shaped prokaryote that causes cholera(x 15,575),Bdellovibrio bacterovorus,它有一条端生鞭毛，这种细菌攻击并杀死比它更大的细菌且以其为食物。,螺旋杆菌,Spirochete bacteria,红弧菌,螺菌,螺旋菌,Measure Unit,：um,Description,：,Bacillus width,length,（0.201.25）（0.3008.00),Spirillumwidthlength（0.31.0）（1.05.0）,Coccusdiameter 0.201.25,3.size of bacteria,Basic structure,Cell wall,Cytoplasmic membrane,Mesosome,Protoplast,Nucleus,Ribosome,Inclusion body,Special structure,Flagella,Capsule,spore,4.structure,细菌的结构,基本结构,细胞壁、细胞膜、细胞质、核质,特殊结构,荚膜、鞭毛、菌毛、芽胞,一.基本结构,（一）细胞壁(cell wall),革兰阳性菌,革兰阴性菌,革兰染色,两类细菌细胞壁的共同组分为肽聚糖，但各有其特殊组分。,革兰染色法：,涂片 风干 固定,结晶紫 碘液 95%乙醇 复红,1min,1min,脱色,1.肽聚糖(peptidoglycan),革兰阳性菌肽聚糖聚糖骨架、四肽侧链、五肽交联桥,青霉素作用点,溶菌酶作用点,N-乙酰葡糖胺,N-乙酰胞壁酸,革兰阴性菌肽聚糖聚糖骨架、四肽侧链,1.肽聚糖(peptidoglycan),2.革兰阳性菌细胞壁特殊组分,壁磷壁酸,膜磷壁酸,3.革兰阴性菌细胞壁特殊组分,3.革兰阴性菌细胞壁特殊组分,脂多糖(lipopolysaccharidLPS),革兰阳性菌与阴性菌细胞壁结构比较,细胞壁,革兰阳性菌,革兰阴性菌,强度,较坚韧,较疏松,厚度,20-80nm,10-15nm,肽聚糖层数,可多达50层,1-2层,肽聚糖含量,占细胞壁干重50%-80%,占细胞壁干重5%-20%,磷壁酸,+,外膜,+,脂蛋白,+,脂多糖,+,维持菌体固有的形态,保护细菌抵抗低渗环境,参与菌体内外的物质交换,菌体表面带有多种抗原分子，可诱发机体的免疫应答。,4.细胞壁的功能,Fig.1.Diagram of a prokaryote cell(Gram-negative).,4.structure,pilus,细菌细胞的透射电子显微镜照片及模式图,Their internal cell structure is simple,，,most of the cellular complexity associated with the cell surface structures.Bacteria lack mitochondria and chloroplasts（叶绿体）,the organelles associated with energy production in eukaryote cells and internal membrane structures such as the endoplasmic reticulum and Golgi apparatus，although some,photo-synthetic bacteria do have internal membranes,.,The cytoplasm of all bacteria is enclosed within a plasma(cytoplasmic)membrane external to which,in most cases of eubacteria,is a rigid cell wall made up of sugars and amino acids called peptidoglycan.The role of the cell wall is to protect the cell from lysis resulting from osmotic pressure and it also gives shape to the cell.,4.1 Cell wall,Some bacteria,the mycoplasma,do not have cell walls and therefore are unable to survive outside an animal host which provides it with the right osmotic environment.Gramnegative bacteria have an additional outer membrane（外膜又称外壁层）containing LPS.External to this may be other layers of poly-saccharide or protein making up a capsule or slime layer.Layers external to the cell wall may be referred to as the cell envelope细胞外膜.The structure of the eubacterial cell envelope is discussed in more details.,summerize,1.Position：,cytoplasmcytoplasmic membranecell wall（out membrane）cell envelope（capsule or slime）,2.Major Function：,The role of the cell wall is to protect the cell from lysis resulting from osmotic pressure and it also gives shape to the cell.（固定细胞外形和提高机械强度，使