华中农业大学微生物英文版课件2.ppt

《华中农业大学微生物英文版课件2.ppt》由会员上传分享，免费在线阅读，更多相关内容在行业资料-天天文库。

1、Chapter2CellBiology2.1Overviewofthestructureofmicrobialcells2.2Procaryoticcellwall2.3Cytoplasmicmembrane2.4Cellulargeneticinformation2.5Cytoplasmicmatrix–RibosomeandInclusions2.6Componentsexternaltothecellwall2.7Bacterialendospores2.8Comparisonoftheprokaryoticandeukar

2、yoticcellChapteroutlineAprocaryoticcellAeucaryoticcellOverviewofcellstructure3.TheircellwallalmostalwayscontainthecomplexpolysaccharidepeptidoglycanTheprokaryoticcell1.Theirgeneticmaterial(DNA)isnotenclosedwithinamembraneandtheylackothermembrane–boundedorganelles2.The

3、irDNAisnotassociatedwithhistidine4.Theyareverysmall!!Size:Mostbacteriafallwithinarangefrom0.2to2.0umindiameterandfrom2to8uminlengthArod-shapedprokaryoteistypicallyabout1-5micrometers(μm)longandabout1μmwideMicroorganismsingeneralareverysmallandarecompletelyinvisibletot

4、henakedeye.Acyanobacterium8x50umsizecomparisonofmicroorganismsVisibilityscaleMetersRelativesizeofMicrobesProkaryotesEukaryotesVirusesNakedeyeLightmicroscopeElectronmicroscopeacellincreasesinsize,itssurfacearea–to–volumeratiodecreasesSurfaceareaandvolumerelationshipsin

5、cellsspirallumShape:BacteriahaveafewbasicshapessphericalcoccusRod-shapedbacillusThecellwallofthebacterialcellisacomplex,semi-rigidstructurethatisresponsibleforthecharacteristicshapeofthecell.Thecellwallsurroundstheunderlying,fragileplasma(cytoplasmic)membraneandprotec

6、tsitandinternalpartsofthecellfromadversechangesinthesurroundingenvironment.Almostallprokaryoteshavecellwalls.ProkaryoticcellwallGram+Gram-SchematicdiagramofbacterialcellwallsBacteriacanbedividedintotwomajorgroups,calledgram-positiveandgram-negative.Theoriginaldistinct

7、ionbetweengram-positiveandgram-negativewasbasedonaspecialstainingprocedure,theGramstainTheGram-positivecellwallhasapeptidoglycanlayerthatisrelativelythick(ca.40nm)andcomprisesapproximately90%ofthecellwall.ThecellwallsofmostGram-positiveeubacteriaalsohaveteichoicacids.

8、Gram-positivecellwallStructureoftheRepeatingUnitinPeptidoglycanTheseconstituentsareconnectedtoformarepeatingstructure,thegly